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	11	<H3><A NAME="chapter4.1"></A>4.1 Initialization parameters</H3>
	12	<P STYLE="margin-bottom: 0in"><BR>
	13	</P>
	14	<TABLE WIDTH=1643 BORDER=1 CELLPADDING=2 CELLSPACING=3>
	15	<COL WIDTH=126>
	16	<COL WIDTH=45>
	17	<COL WIDTH=159>
	18	<COL WIDTH=1280>
	19	<TR>
	20	<TD WIDTH=126>
	21	<P><FONT SIZE=4><B>Parameter name</B></FONT></P>
	22	</TD>
	23	<TD WIDTH=45>
	24	<P><FONT SIZE=4><B>Type</B></FONT></P>
	25	</TD>
	26	<TD WIDTH=159>
	27	<P><FONT SIZE=4><B>Default</B></FONT> <BR><FONT SIZE=4><B>value</B></FONT></P>
	28	</TD>
	29	<TD WIDTH=1280>
	30	<P><FONT SIZE=4><B>Explanation</B></FONT></P>
	31	</TD>
	32	</TR>
	33	<TR>
	34	<TD WIDTH=126>
	35	<P><A NAME="adjust_mixing_length"></A><B>adjust_mixing_length</B></P>
	36	</TD>
	37	<TD WIDTH=45>
	38	<P>L</P>
	39	</TD>
	40	<TD WIDTH=159>
	41	<P><I>.F.</I></P>
	42	</TD>
	43	<TD WIDTH=1280>
	44	<P STYLE="font-style: normal">Near-surface adjustment of the
	45	mixing length to the Prandtl-layer law.
	46	</P>
	47	<P>Usually the mixing length in LES models l<SUB>LES</SUB> depends
	48	(as in PALM) on the grid size and is possibly restricted further
	49	in case of stable stratification and near the lower wall (see
	50	parameter <A HREF="#wall_adjustment">wall_adjustment</A>). With
	51	<B>adjust_mixing_length</B> = <I>.T.</I> the Prandtl' mixing
	52	length l<SUB>PR</SUB> = kappa * z/phi is calculated and the mixing
	53	length actually used in the model is set l = MIN (l<SUB>LES</SUB>,
	54	l<SUB>PR</SUB>). This usually gives a decrease of the mixing
	55	length at the bottom boundary and considers the fact that eddy
	56	sizes decrease in the vicinity of the wall.
	57	</P>
	58	<P STYLE="font-style: normal"><B>Warning:</B> So far, there is no
	59	good experience with <B>adjust_mixing_length</B> = <I>.T.</I> !
	60	</P>
	61	<P>With <B>adjust_mixing_length</B> = <I>.T.</I> and the
	62	Prandtl-layer being switched on (see <A HREF="#prandtl_layer">prandtl_layer</A>)
	63	<I>'(u)* 2+neumann'</I> should always be set as the lower
	64	boundary condition for the TKE (see <A HREF="#bc_e_b">bc_e_b</A>),
	65	otherwise the near-surface value of the TKE is not in agreement
	66	with the Prandtl-layer law (Prandtl-layer law and
	67	Prandtl-Kolmogorov-Ansatz should provide the same value for K<SUB>m</SUB>).
	68	A warning is given, if this is not the case.</P>
	69	</TD>
	70	</TR>
	71	<TR>
	72	<TD WIDTH=126>
	73	<P><A NAME="alpha_surface"></A><B>alpha_surface</B></P>
	74	</TD>
	75	<TD WIDTH=45>
	76	<P>R</P>
	77	</TD>
	78	<TD WIDTH=159>
	79	<P><I>0.0</I></P>
	80	</TD>
	81	<TD WIDTH=1280>
	82	<P STYLE="font-style: normal">Inclination of the model domain with
	83	respect to the horizontal (in degrees).
	84	</P>
	85	<P STYLE="font-style: normal">By means of <B>alpha_surface</B> the
	86	model domain can be inclined in x-direction with respect to the
	87	horizontal. In this way flows over inclined surfaces (e.g.
	88	drainage flows, gravity flows) can be simulated. In case of
	89	<B>alpha_surface </B>/= <I>0</I> the buoyancy term appears both in
	90	the equation of motion of the u-component and of the w-component.</P>
	91	<P><SPAN STYLE="font-style: normal">An inclination is only
	92	possible in case of cyclic horizontal boundary conditions along x
	93	AND y (see <A HREF="#bc_lr">bc_lr</A> and <A HREF="#bc_ns">bc_ns</A>)
	94	and <A HREF="#topography">topography</A> = </SPAN><I>'flat'</I><SPAN STYLE="font-style: normal">.
	95	</SPAN>
	96	</P>
	97	<P>Runs with inclined surface still require additional
	98	user-defined code as well as modifications to the default code.
	99	Please ask the <A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/PALM_group.html#0">PALM
	100	developer  group</A>.</P>
	101	</TD>
	102	</TR>
	103	<TR>
	104	<TD WIDTH=126>
	105	<P><A NAME="bc_e_b"></A><B>bc_e_b</B></P>
	106	</TD>
	107	<TD WIDTH=45>
	108	<P>C * 20</P>
	109	</TD>
	110	<TD WIDTH=159>
	111	<P><I>'neumann'</I></P>
	112	</TD>
	113	<TD WIDTH=1280>
	114	<P STYLE="font-style: normal">Bottom boundary condition of the
	115	TKE.
	116	</P>
	117	<P><B>bc_e_b</B> may be set to <I>'neumann'</I> or <I>'(u*)
	118	** 2+neumann'</I>. <B>bc_e_b</B> = <I>'neumann'</I> yields to
	119	e(k=0)=e(k=1) (Neumann boundary condition), where e(k=1) is
	120	calculated via the prognostic TKE equation. Choice of
	121	<I>'(u)*2+neumann'</I> also yields to e(k=0)=e(k=1), but the TKE
	122	at the Prandtl-layer top (k=1) is calculated diagnostically by
	123	e(k=1)=(us/0.1)**2. However, this is only allowed if a
	124	Prandtl-layer is used (<A HREF="#prandtl_layer">prandtl_layer</A>).
	125	If this is not the case, a warning is given and <B>bc_e_b</B> is
	126	reset to <I>'neumann'</I>.
	127	</P>
	128	<P STYLE="font-style: normal">At the top boundary a Neumann
	129	boundary condition is generally used: (e(nz+1) = e(nz)).</P>
	130	</TD>
	131	</TR>
	132	<TR>
	133	<TD WIDTH=126>
	134	<P><A NAME="bc_lr"></A><B>bc_lr</B></P>
	135	</TD>
	136	<TD WIDTH=45>
	137	<P>C * 20</P>
	138	</TD>
	139	<TD WIDTH=159>
	140	<P><I>'cyclic'</I></P>
	141	</TD>
	142	<TD WIDTH=1280>
	143	<P>Boundary condition along x (for all quantities).<BR><BR>By
	144	default, a cyclic boundary condition is used along x.<BR><BR><B>bc_lr</B>
	145	may also be assigned the values <I>'dirichlet/radiation'</I>
	146	(inflow from left, outflow to the right) or <I>'radiation/dirichlet'</I>
	147	(inflow from right, outflow to the left). This requires the
	148	multi-grid method to be used for solving the Poisson equation for
	149	perturbation pressure (see <A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">psolver</A>)
	150	and it also requires cyclic boundary conditions along y
	151	(see <A HREF="#bc_ns">bc_ns</A>).<BR><BR>In case of these
	152	non-cyclic lateral boundaries, a Dirichlet condition is used at
	153	the inflow for all quantities (initial vertical profiles - see
	154	<A HREF="#initializing_actions">initializing_actions</A> - are
	155	fixed during the run) except u, to which a Neumann (zero gradient)
	156	condition is applied. At the outflow, a radiation condition is
	157	used for all velocity components, while a Neumann (zero gradient)
	158	condition is used for the scalars. For perturbation pressure
	159	Neumann (zero gradient) conditions are assumed both at the inflow
	160	and at the outflow.<BR><BR>When using non-cyclic lateral
	161	boundaries, a filter is applied to the velocity field in the
	162	vicinity of the outflow in order to suppress any reflections of
	163	outgoing disturbances (see <A HREF="#km_damp_max">km_damp_max</A>
	164	and <A HREF="#outflow_damping_width">outflow_damping_width</A>).<BR><BR>In
	165	order to maintain a turbulent state of the flow, it may be
	166	neccessary to continuously impose perturbations on the horizontal
	167	velocity field in the vicinity of the inflow throughout the whole
	168	run. This can be switched on using <A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#create_disturbances">create_disturbances</A>.
	169	The horizontal range to which these perturbations are applied is
	170	controlled by the parameters <A HREF="#inflow_disturbance_begin">inflow_disturbance_begin</A>
	171	and <A HREF="#inflow_disturbance_end">inflow_disturbance_end</A>.
	172	The vertical range and the perturbation amplitude are given by
	173	<A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_level_b</A>,
	174	<A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_level_t</A>,
	175	and <A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_amplitude</A>.
	176	The time interval at which perturbations are to be imposed is set
	177	by <A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#dt_disturb">dt_disturb</A>.<BR><BR>In
	178	case of non-cyclic horizontal boundaries <A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#call_psolver_at_all_substeps">call_psolver
	179	at_all_substeps</A> = .T. should be used.<BR><BR><B>Note:</B><BR>Using
	180	non-cyclic lateral boundaries requires very sensitive adjustments
	181	of the inflow (vertical profiles) and the bottom boundary
	182	conditions, e.g. a surface heating should not be applied near the
	183	inflow boundary because this may significantly disturb the inflow.
	184	Please check the model results very carefully.</P>
	185	</TD>
	186	</TR>
	187	<TR>
	188	<TD WIDTH=126>
	189	<P><A NAME="bc_ns"></A><B>bc_ns</B></P>
	190	</TD>
	191	<TD WIDTH=45>
	192	<P>C * 20</P>
	193	</TD>
	194	<TD WIDTH=159>
	195	<P><I>'cyclic'</I></P>
	196	</TD>
	197	<TD WIDTH=1280>
	198	<P>Boundary condition along y (for all quantities).<BR><BR>By
	199	default, a cyclic boundary condition is used along y.<BR><BR><B>bc_ns</B>
	200	may also be assigned the values <I>'dirichlet/radiation'</I>
	201	(inflow from rear ("north"), outflow to the front
	202	("south")) or <I>'radiation/dirichlet'</I> (inflow from
	203	front ("south"), outflow to the rear ("north")).
	204	This requires the multi-grid method to be used for solving the
	205	Poisson equation for perturbation pressure (see <A HREF="chapter_4.2.html#psolver">psolver</A>)
	206	and it also requires cyclic boundary conditions along x
	207	(see<BR><A HREF="#bc_lr">bc_lr</A>).<BR><BR>In case of these
	208	non-cyclic lateral boundaries, a Dirichlet condition is used at
	209	the inflow for all quantities (initial vertical profiles - see
	210	<A HREF="#initializing_actions">initializing_actions</A> - are
	211	fixed during the run) except u, to which a Neumann (zero gradient)
	212	condition is applied. At the outflow, a radiation condition is
	213	used for all velocity components, while a Neumann (zero gradient)
	214	condition is used for the scalars. For perturbation pressure
	215	Neumann (zero gradient) conditions are assumed both at the inflow
	216	and at the outflow.<BR><BR>For further details regarding
	217	non-cyclic lateral boundary conditions see <A HREF="#bc_lr">bc_lr</A>.</P>
	218	</TD>
	219	</TR>
	220	<TR>
	221	<TD WIDTH=126>
	222	<P><A NAME="bc_p_b"></A><B>bc_p_b</B></P>
	223	</TD>
	224	<TD WIDTH=45>
	225	<P>C * 20</P>
	226	</TD>
	227	<TD WIDTH=159>
	228	<P><I>'neumann'</I></P>
	229	</TD>
	230	<TD WIDTH=1280>
	231	<P STYLE="font-style: normal">Bottom boundary condition of the
	232	perturbation pressure.
	233	</P>
	234	<P>Allowed values are <I>'dirichlet'</I>, <I>'neumann'</I> and
	235	<I>'neumann+inhomo'</I>.  <I>'dirichlet'</I> sets
	236	p(k=0)=0.0,  <I>'neumann'</I> sets p(k=0)=p(k=1).
	237	<I>'neumann+inhomo'</I> corresponds to an extended Neumann
	238	boundary condition where heat flux or temperature inhomogeneities
	239	near the surface (pt(k=1))  are additionally regarded (see
	240	Shen and LeClerc (1995, Q.J.R. Meteorol. Soc., 1209)). This
	241	condition is only permitted with the Prandtl-layer switched on
	242	(<A HREF="#prandtl_layer">prandtl_layer</A>), otherwise the run is
	243	terminated.
	244	</P>
	245	<P>Since at the bottom boundary of the model the vertical velocity
	246	disappears (w(k=0) = 0.0), the consistent Neumann condition
	247	(<I>'neumann'</I> or <I>'neumann+inhomo'</I>) dp/dz = 0 should be
	248	used, which leaves the vertical component w unchanged when the
	249	pressure solver is applied. Simultaneous use of the Neumann
	250	boundary conditions both at the bottom and at the top boundary
	251	(<A HREF="#bc_p_t">bc_p_t</A>) usually yields no consistent
	252	solution for the perturbation pressure and should be avoided.</P>
	253	</TD>
	254	</TR>
	255	<TR>
	256	<TD WIDTH=126>
	257	<P><A NAME="bc_p_t"></A><B>bc_p_t</B></P>
	258	</TD>
	259	<TD WIDTH=45>
	260	<P>C * 20</P>
	261	</TD>
	262	<TD WIDTH=159>
	263	<P><I>'dirichlet'</I></P>
	264	</TD>
	265	<TD WIDTH=1280>
	266	<P STYLE="font-style: normal">Top boundary condition of the
	267	perturbation pressure.
	268	</P>
	269	<P STYLE="font-style: normal">Allowed values are <I>'dirichlet'</I>
	270	(p(k=nz+1)= 0.0) or <I>'neumann'</I> (p(k=nz+1)=p(k=nz)).
	271	</P>
	272	<P>Simultaneous use of Neumann boundary conditions both at the top
	273	and bottom boundary (<A HREF="#bc_p_b">bc_p_b</A>) usually yields
	274	no consistent solution for the perturbation pressure and should be
	275	avoided. Since at the bottom boundary the Neumann condition
	276	is a good choice (see <A HREF="#bc_p_b">bc_p_b</A>), a Dirichlet
	277	condition should be set at the top boundary.</P>
	278	</TD>
	279	</TR>
	280	<TR>
	281	<TD WIDTH=126>
	282	<P><A NAME="bc_pt_b"></A><B>bc_pt_b</B></P>
	283	</TD>
	284	<TD WIDTH=45>
	285	<P>C*20</P>
	286	</TD>
	287	<TD WIDTH=159>
	288	<P><I>'dirichlet'</I></P>
	289	</TD>
	290	<TD WIDTH=1280>
	291	<P STYLE="font-style: normal">Bottom boundary condition of the
	292	potential temperature.
	293	</P>
	294	<P>Allowed values are <I>'dirichlet'</I> (pt(k=0) = const. =
	295	<A HREF="#pt_surface">pt_surface</A> + <A HREF="#pt_surface_initial_change">pt_surface_initial_change</A>;
	296	the user may change this value during the run using user-defined
	297	code) and <I>'neumann'</I> (pt(k=0)=pt(k=1)).  <BR>When a
	298	constant surface sensible heat flux is used (<A HREF="#surface_heatflux">surface_heatflux</A>),
	299	<B>bc_pt_b</B> = <I>'neumann'</I> must be used, because otherwise
	300	the resolved scale may contribute to the surface flux so that a
	301	constant value cannot be guaranteed.</P>
	302	<P>In the <A HREF="chapter_3.8.html">coupled</A> atmosphere
	303	executable, <A HREF="chapter_4.2.html#bc_pt_b">bc_pt_b</A> is
	304	internally set and does not need to be prescribed.</P>
	305	</TD>
	306	</TR>
	307	<TR>
	308	<TD WIDTH=126>
	309	<P><A NAME="pc_pt_t"></A><B>bc_pt_t</B></P>
	310	</TD>
	311	<TD WIDTH=45>
	312	<P>C * 20</P>
	313	</TD>
	314	<TD WIDTH=159>
	315	<P><I>'initial_ gradient'</I></P>
	316	</TD>
	317	<TD WIDTH=1280>
	318	<P STYLE="font-style: normal">Top boundary condition of the
	319	potential temperature.
	320	</P>
	321	<P>Allowed are the values <I>'dirichlet' </I>(pt(k=nz+1) does not
	322	change during the run), <I>'neumann'</I> (pt(k=nz+1)=pt(k=nz)),
	323	and <I>'initial_gradient'</I>. With the
	324	'initial_gradient'-condition the value of the temperature gradient
	325	at the top is calculated from the initial temperature profile (see
	326	<A HREF="#pt_surface">pt_surface</A>, <A HREF="#pt_vertical_gradient">pt_vertical_gradient</A>)
	327	by bc_pt_t_val = (pt_init(k=nz+1) - pt_init(k=nz)) /
	328	dzu(nz+1).<BR>Using this value (assumed constant during the run)
	329	the temperature boundary values are calculated as
	330	</P>
	331	<UL>
	332	<P STYLE="font-style: normal">pt(k=nz+1) = pt(k=nz) + bc_pt_t_val
	333	* dzu(nz+1)</P>
	334	</UL>
	335	<P><SPAN STYLE="font-style: normal">(up to k=nz the prognostic
	336	equation for the temperature is solved).<BR>When a constant
	337	sensible heat flux is used at the top boundary (<A HREF="#top_heatflux">top_heatflux</A>),
	338	</SPAN><SPAN STYLE="font-style: normal"><B>bc_pt_t</B></SPAN> <SPAN STYLE="font-style: normal">=
	339	</SPAN><I>'neumann'</I> <SPAN STYLE="font-style: normal">must be
	340	used, because otherwise the resolved scale may contribute to the
	341	top flux so that a constant value cannot be guaranteed.</SPAN></P>
	342	</TD>
	343	</TR>
	344	<TR>
	345	<TD WIDTH=126>
	346	<P><A NAME="bc_q_b"></A><B>bc_q_b</B></P>
	347	</TD>
	348	<TD WIDTH=45>
	349	<P>C * 20</P>
	350	</TD>
	351	<TD WIDTH=159>
	352	<P><I>'dirichlet'</I></P>
	353	</TD>
	354	<TD WIDTH=1280>
	355	<P STYLE="font-style: normal">Bottom boundary condition of the
	356	specific humidity / total water content.
	357	</P>
	358	<P>Allowed values are <I>'dirichlet'</I> (q(k=0) = const. =
	359	<A HREF="#q_surface">q_surface</A> + <A HREF="#q_surface_initial_change">q_surface_initial_change</A>;
	360	the user may change this value during the run using user-defined
	361	code) and <I>'neumann'</I> (q(k=0)=q(k=1)).  <BR>When a
	362	constant surface latent heat flux is used (<A HREF="#surface_waterflux">surface_waterflux</A>),
	363	<B>bc_q_b</B> = <I>'neumann'</I> must be used, because otherwise
	364	the resolved scale may contribute to the surface flux so that a
	365	constant value cannot be guaranteed.</P>
	366	</TD>
	367	</TR>
	368	<TR>
	369	<TD WIDTH=126>
	370	<P><A NAME="bc_q_t"></A><B>bc_q_t</B></P>
	371	</TD>
	372	<TD WIDTH=45>
	373	<P><I>C * 20</I></P>
	374	</TD>
	375	<TD WIDTH=159>
	376	<P><I>'neumann'</I></P>
	377	</TD>
	378	<TD WIDTH=1280>
	379	<P STYLE="font-style: normal">Top boundary condition of the
	380	specific humidity / total water content.
	381	</P>
	382	<P>Allowed are the values <I>'dirichlet'</I> (q(k=nz) and
	383	q(k=nz+1) do not change during the run) and <I>'neumann'</I>. With
	384	the Neumann boundary condition the value of the humidity gradient
	385	at the top is calculated from the initial humidity profile (see
	386	<A HREF="#q_surface">q_surface</A>, <A HREF="#q_vertical_gradient">q_vertical_gradient</A>)
	387	by: bc_q_t_val = ( q_init(k=nz) - q_init(k=nz-1)) / dzu(nz).<BR>Using
	388	this value (assumed constant during the run) the humidity boundary
	389	values are calculated as
	390	</P>
	391	<UL>
	392	<P STYLE="font-style: normal">q(k=nz+1) =q(k=nz) + bc_q_t_val *
	393	dzu(nz+1)</P>
	394	</UL>
	395	<P STYLE="font-style: normal">(up tp k=nz the prognostic equation
	396	for q is solved).
	397	</P>
	398	</TD>
	399	</TR>
	400	<TR>
	401	<TD WIDTH=126>
	402	<P><A NAME="bc_s_b"></A><B>bc_s_b</B></P>
	403	</TD>
	404	<TD WIDTH=45>
	405	<P>C * 20</P>
	406	</TD>
	407	<TD WIDTH=159>
	408	<P><I>'dirichlet'</I></P>
	409	</TD>
	410	<TD WIDTH=1280>
	411	<P STYLE="font-style: normal">Bottom boundary condition of the
	412	scalar concentration.
	413	</P>
	414	<P>Allowed values are <I>'dirichlet'</I> (s(k=0) = const. =
	415	<A HREF="#s_surface">s_surface</A> + <A HREF="#s_surface_initial_change">s_surface_initial_change</A>;
	416	the user may change this value during the run using user-defined
	417	code) and <I>'neumann'</I> (s(k=0) = s(k=1)).  <BR>When a
	418	constant surface concentration flux is used (<A HREF="#surface_scalarflux">surface_scalarflux</A>),
	419	<B>bc_s_b</B> = <I>'neumann'</I> must be used, because otherwise
	420	the resolved scale may contribute to the surface flux so that a
	421	constant value cannot be guaranteed.</P>
	422	</TD>
	423	</TR>
	424	<TR>
	425	<TD WIDTH=126>
	426	<P><A NAME="bc_s_t"></A><B>bc_s_t</B></P>
	427	</TD>
	428	<TD WIDTH=45>
	429	<P>C * 20</P>
	430	</TD>
	431	<TD WIDTH=159>
	432	<P><I>'neumann'</I></P>
	433	</TD>
	434	<TD WIDTH=1280>
	435	<P STYLE="font-style: normal">Top boundary condition of the scalar
	436	concentration.
	437	</P>
	438	<P>Allowed are the values <I>'dirichlet'</I> (s(k=nz) and
	439	s(k=nz+1) do not change during the run) and <I>'neumann'</I>. With
	440	the Neumann boundary condition the value of the scalar
	441	concentration gradient at the top is calculated from the initial
	442	scalar concentration profile (see <A HREF="#s_surface">s_surface</A>,
	443	<A HREF="#s_vertical_gradient">s_vertical_gradient</A>) by:
	444	bc_s_t_val = (s_init(k=nz) - s_init(k=nz-1)) / dzu(nz).<BR>Using
	445	this value (assumed constant during the run) the concentration
	446	boundary values are calculated as
	447	</P>
	448	<UL>
	449	<P STYLE="font-style: normal">s(k=nz+1) = s(k=nz) + bc_s_t_val *
	450	dzu(nz+1)</P>
	451	</UL>
	452	<P STYLE="font-style: normal">(up to k=nz the prognostic equation
	453	for the scalar concentration is solved).</P>
	454	</TD>
	455	</TR>
	456	<TR>
	457	<TD WIDTH=126>
	458	<P><A NAME="bc_sa_t"></A><B>bc_sa_t</B></P>
	459	</TD>
	460	<TD WIDTH=45>
	461	<P>C * 20</P>
	462	</TD>
	463	<TD WIDTH=159>
	464	<P><I>'neumann'</I></P>
	465	</TD>
	466	<TD WIDTH=1280>
	467	<P STYLE="font-style: normal">Top boundary condition of the
	468	salinity.
	469	</P>
	470	<P>This parameter only comes into effect for ocean runs (see
	471	parameter <A HREF="#ocean">ocean</A>).</P>
	472	<P><SPAN STYLE="font-style: normal">Allowed are the values
	473	</SPAN><I>'dirichlet' </I><SPAN STYLE="font-style: normal">(sa(k=nz+1)
	474	does not change during the run) and </SPAN><I>'neumann'</I>
	475	<SPAN STYLE="font-style: normal">(sa(k=nz+1)=sa(k=nz)). <BR><BR>When
	476	a constant salinity flux is used at the top boundary
	477	(<A HREF="#top_salinityflux">top_salinityflux</A>), </SPAN><SPAN STYLE="font-style: normal"><B>bc_sa_t</B></SPAN>
	478	<SPAN STYLE="font-style: normal">= </SPAN><I>'neumann'</I> <SPAN STYLE="font-style: normal">must
	479	be used, because otherwise the resolved scale may contribute to
	480	the top flux so that a constant value cannot be guaranteed.</SPAN></P>
	481	</TD>
	482	</TR>
	483	<TR>
	484	<TD WIDTH=126>
	485	<P><A NAME="bc_uv_b"></A><B>bc_uv_b</B></P>
	486	</TD>
	487	<TD WIDTH=45>
	488	<P>C * 20</P>
	489	</TD>
	490	<TD WIDTH=159>
	491	<P><I>'dirichlet'</I></P>
	492	</TD>
	493	<TD WIDTH=1280>
	494	<P STYLE="font-style: normal">Bottom boundary condition of the
	495	horizontal velocity components u and v.
	496	</P>
	497	<P>Allowed values are <I>'dirichlet' </I>and <I>'neumann'</I>.
	498	<B>bc_uv_b</B> = <I>'dirichlet'</I> yields the no-slip condition
	499	with u=v=0 at the bottom. Due to the staggered grid u(k=0) and
	500	v(k=0) are located at z = - 0,5 * <A HREF="#dz">dz</A> (below the
	501	bottom), while u(k=1) and v(k=1) are located at z = +0,5 * dz.
	502	u=v=0 at the bottom is guaranteed using mirror boundary
	503	condition:
	504	</P>
	505	<UL>
	506	<P STYLE="font-style: normal">u(k=0) = - u(k=1) and v(k=0) = -
	507	v(k=1)</P>
	508	</UL>
	509	<P><SPAN STYLE="font-style: normal">The Neumann boundary condition
	510	yields the free-slip condition with u(k=0) = u(k=1) and v(k=0) =
	511	v(k=1). With Prandtl - layer switched on (see <A HREF="#prandtl_layer">prandtl_layer</A>),
	512	the free-slip condition is not allowed (otherwise the run will be
	513	terminated)</SPAN><FONT COLOR="#000000"><SPAN STYLE="font-style: normal">.</SPAN></FONT></P>
	514	</TD>
	515	</TR>
	516	<TR>
	517	<TD WIDTH=126>
	518	<P><A NAME="bc_uv_t"></A><B>bc_uv_t</B></P>
	519	</TD>
	520	<TD WIDTH=45>
	521	<P>C * 20</P>
	522	</TD>
	523	<TD WIDTH=159>
	524	<P><I>'dirichlet'</I></P>
	525	</TD>
	526	<TD WIDTH=1280>
	527	<P STYLE="font-style: normal">Top boundary condition of the
	528	horizontal velocity components u and v.
	529	</P>
	530	<P>Allowed values are <I>'dirichlet'</I>, <I>'dirichlet_0'</I> and
	531	<I>'neumann'</I>. The Dirichlet condition yields u(k=nz+1) =
	532	ug(nz+1) and v(k=nz+1) = vg(nz+1), Neumann condition yields the
	533	free-slip condition with u(k=nz+1) = u(k=nz) and v(k=nz+1) =
	534	v(k=nz) (up to k=nz the prognostic equations for the velocities
	535	are solved). The special condition <I>'dirichlet_0'</I> can
	536	be used for channel flow, it yields the no-slip condition
	537	u(k=nz+1) = ug(nz+1) = 0 and v(k=nz+1) = vg(nz+1) = 0.</P>
	538	<P>In the <A HREF="chapter_3.8.html">coupled</A> ocean executable,
	539	<A HREF="chapter_4.2.html#bc_uv_t">bc_uv_t</A> is internally
	540	set ('neumann') and does not need to be prescribed.</P>
	541	</TD>
	542	</TR>
	543	<TR>
	544	<TD WIDTH=126>
	545	<P><A NAME="bottom_salinityflux"></A><B>bottom_salinityflux</B></P>
	546	</TD>
	547	<TD WIDTH=45>
	548	<P>R</P>
	549	</TD>
	550	<TD WIDTH=159>
	551	<P><I>0.0</I></P>
	552	</TD>
	553	<TD WIDTH=1280>
	554	<P>Kinematic salinity flux near the surface (in psu m/s). </P>
	555	<P>This parameter only comes into effect for ocean runs (see
	556	parameter <A HREF="#ocean">ocean</A>).
	557	</P>
	558	<P>The respective salinity flux value is used as bottom
	559	(horizontally homogeneous) boundary condition for the salinity
	560	equation. This additionally requires that a Neumann condition must
	561	be used for the salinity, which is currently the only available
	562	condition.</P>
	563	</TD>
	564	</TR>
	565	<TR>
	566	<TD WIDTH=126>
	567	<P><A NAME="building_height"></A><B>building_height</B></P>
	568	</TD>
	569	<TD WIDTH=45>
	570	<P>R</P>
	571	</TD>
	572	<TD WIDTH=159>
	573	<P><I>50.0</I></P>
	574	</TD>
	575	<TD WIDTH=1280>
	576	<P>Height of a single building in m.<BR><BR><B>building_height</B>
	577	must be less than the height of the model domain. This parameter
	578	requires the use of <A HREF="#topography">topography</A> =
	579	<I>'single_building'</I>.</P>
	580	</TD>
	581	</TR>
	582	<TR>
	583	<TD WIDTH=126>
	584	<P><A NAME="building_length_x"></A><B>building_length_x</B></P>
	585	</TD>
	586	<TD WIDTH=45>
	587	<P>R</P>
	588	</TD>
	589	<TD WIDTH=159>
	590	<P><I>50.0</I></P>
	591	</TD>
	592	<TD WIDTH=1280>
	593	<P>Width of a single building in m.<BR><BR>Currently,
	594	<B>building_length_x</B> must be at least <I>3 * <A HREF="#dx">dx</A></I>
	595	and no more than <I>( <A HREF="#nx">nx</A></I> <I>- 1 ) * <A HREF="#dx">dx</A>
	596	- <A HREF="#building_wall_left">building_wall_left</A></I>. This
	597	parameter requires the use of <A HREF="#topography">topography</A>
	598	= <I>'single_building'</I>.</P>
	599	</TD>
	600	</TR>
	601	<TR>
	602	<TD WIDTH=126>
	603	<P><A NAME="building_length_y"></A><B>building_length_y</B></P>
	604	</TD>
	605	<TD WIDTH=45>
	606	<P>R</P>
	607	</TD>
	608	<TD WIDTH=159>
	609	<P><I>50.0</I></P>
	610	</TD>
	611	<TD WIDTH=1280>
	612	<P>Depth of a single building in m.<BR><BR>Currently,
	613	<B>building_length_y</B> must be at least <I>3 * <A HREF="#dy">dy</A></I>
	614	and no more than <I>( <A HREF="#ny">ny</A></I> <I>- 1 ) </I>
	615	<I>* <A HREF="#dy">dy</A></I> <I>- <A HREF="#building_wall_south">building_wall_south</A></I>.
	616	This parameter requires the use of <A HREF="#topography">topography</A>
	617	= <I>'single_building'</I>.</P>
	618	</TD>
	619	</TR>
	620	<TR>
	621	<TD WIDTH=126>
	622	<P><A NAME="building_wall_left"></A><B>building_wall_left</B></P>
	623	</TD>
	624	<TD WIDTH=45>
	625	<P>R</P>
	626	</TD>
	627	<TD WIDTH=159>
	628	<P><I>building centered in x-direction</I></P>
	629	</TD>
	630	<TD WIDTH=1280>
	631	<P>x-coordinate of the left building wall (distance between the
	632	left building wall and the left border of the model domain) in
	633	m.<BR><BR>Currently, <B>building_wall_left</B> must be at least <I>1
	634	* <A HREF="#dx">dx</A></I> and less than <I>( <A HREF="#nx">nx</A>
	635	- 1 ) * <A HREF="#dx">dx</A> -  <A HREF="#building_length_x">building_length_x</A></I>.
	636	This parameter requires the use of <A HREF="#topography">topography</A>
	637	= <I>'single_building'</I>.<BR><BR>The default
	638	value <B>building_wall_left</B> = <I>( ( <A HREF="#nx">nx</A> +
	639	1 ) * <A HREF="#dx">dx</A> -  <A HREF="#building_length_x">building_length_x</A>
	640	) / 2</I> centers the building in x-direction. <FONT COLOR="#000000">Due
	641	to the staggered grid the building will be displaced by -0.5 <A HREF="#dx">dx</A>
	642	in x-direction and -0.5 <A HREF="#dy">dy</A> in y-direction.</FONT>
	643	</P>
	644	</TD>
	645	</TR>
	646	<TR>
	647	<TD WIDTH=126>
	648	<P><A NAME="building_wall_south"></A><B>building_wall_south</B></P>
	649	</TD>
	650	<TD WIDTH=45>
	651	<P>R</P>
	652	</TD>
	653	<TD WIDTH=159>
	654	<P><I>building centered in y-direction</I></P>
	655	</TD>
	656	<TD WIDTH=1280>
	657	<P>y-coordinate of the South building wall (distance between the
	658	South building wall and the South border of the model domain) in
	659	m.<BR><BR>Currently, <B>building_wall_south</B> must be at least <I>1
	660	* <A HREF="#dy">dy</A></I> and less than <I>( <A HREF="#ny">ny</A>
	661	- 1 ) * <A HREF="#dy">dy</A> -  <A HREF="#building_length_y">building_length_y</A></I>.
	662	This parameter requires the use of <A HREF="#topography">topography</A>
	663	= <I>'single_building'</I>.<BR><BR>The default
	664	value <B>building_wall_south</B> = <I>( ( <A HREF="#ny">ny</A> +
	665	1 ) * <A HREF="#dy">dy</A> -  <A HREF="#building_length_y">building_length_y</A>
	666	) / 2</I> centers the building in y-direction. <FONT COLOR="#000000">Due
	667	to the staggered grid the building will be displaced by -0.5 <A HREF="#dx">dx</A>
	668	in x-direction and -0.5 <A HREF="#dy">dy</A> in y-direction.</FONT>
	669	</P>
	670	</TD>
	671	</TR>
	672	<TR>
	673	<TD WIDTH=126>
	674	<P><A NAME="canopy_mode"></A><B>canopy_mode</B></P>
	675	</TD>
	676	<TD WIDTH=45>
	677	<P>C * 20</P>
	678	</TD>
	679	<TD WIDTH=159>
	680	<P><I>'block'</I></P>
	681	</TD>
	682	<TD WIDTH=1280>
	683	<P>Canopy mode.<BR><BR><FONT COLOR="#000000">Besides using the
	684	default value, that will create a horizontally homogeneous plant
	685	canopy that extends over the total horizontal extension of the
	686	model domain, the user may add code to the user interface
	687	subroutine <A HREF="chapter_3.5.1.html#user_init_plant_canopy">user_init_plant_canopy</A>
	688	to allow further canopy modes. <BR><BR>The setting of
	689	<A HREF="#canopy_mode">canopy_mode</A> becomes only active,
	690	if <A HREF="#plant_canopy">plant_canopy</A> has been set </FONT><FONT COLOR="#000000"><I>.T.</I></FONT><FONT COLOR="#000000">
	691	and a non-zero <A HREF="#drag_coefficient">drag_coefficient</A>
	692	has been defined.</FONT></P>
	693	</TD>
	694	</TR>
	695	<TR>
	696	<TD WIDTH=126>
	697	<P><A NAME="canyon_height"></A><B>canyon_height</B></P>
	698	</TD>
	699	<TD WIDTH=45>
	700	<P>R</P>
	701	</TD>
	702	<TD WIDTH=159>
	703	<P><I>50.0</I></P>
	704	</TD>
	705	<TD WIDTH=1280>
	706	<P>Street canyon height in m.<BR><BR><B>canyon_height</B> must be
	707	less than the height of the model domain. This parameter
	708	requires <A HREF="#topography">topography</A> =
	709	<I>'single_street_canyon'</I>.</P>
	710	</TD>
	711	</TR>
	712	<TR>
	713	<TD WIDTH=126>
	714	<P><A NAME="canyon_width_x"></A><B>canyon_width_x</B></P>
	715	</TD>
	716	<TD WIDTH=45>
	717	<P>R</P>
	718	</TD>
	719	<TD WIDTH=159>
	720	<P><I>9999999.9</I></P>
	721	</TD>
	722	<TD WIDTH=1280>
	723	<P>Street canyon width in x-direction in m.<BR><BR>Currently,
	724	<B>canyon_width_x</B> must be at least <I>3 * <A HREF="#dx">dx</A></I>
	725	and no more than <I>( <A HREF="#nx">nx</A></I> <I>- 1 ) * <A HREF="#dx">dx</A>
	726	- <A HREF="#canyon_wall_left">canyon_wall_left</A></I>. This
	727	parameter requires <A HREF="#topography">topography</A> =
	728	<I>'single_street_canyon'</I>. A non-default value implies a
	729	canyon orientation in y-direction.</P>
	730	</TD>
	731	</TR>
	732	<TR>
	733	<TD WIDTH=126>
	734	<P><A NAME="canyon_width_y"></A><B>canyon_width_y</B></P>
	735	</TD>
	736	<TD WIDTH=45>
	737	<P>R</P>
	738	</TD>
	739	<TD WIDTH=159>
	740	<P><I>9999999.9</I></P>
	741	</TD>
	742	<TD WIDTH=1280>
	743	<P>Street canyon width in y-direction in m.<BR><BR>Currently,
	744	<B>canyon_width_y</B> must be at least <I>3 * <A HREF="#dy">dy</A></I>
	745	and no more than <I>( <A HREF="#ny">ny</A></I> <I>- 1 ) </I>
	746	<I>* <A HREF="#dy">dy</A></I> <I>- <A HREF="#canyon_wall_south">canyon_wall_south</A></I>.
	747	This parameter requires <A HREF="#topography">topography</A>
	748	= <I>'single_street_canyon</I>. A non-default value implies a
	749	canyon orientation in x-direction.</P>
	750	</TD>
	751	</TR>
	752	<TR>
	753	<TD WIDTH=126>
	754	<P><A NAME="canyon_wall_left"></A><B>canyon_wall_left</B></P>
	755	</TD>
	756	<TD WIDTH=45>
	757	<P>R</P>
	758	</TD>
	759	<TD WIDTH=159>
	760	<P><I>canyon centered in x-direction</I></P>
	761	</TD>
	762	<TD WIDTH=1280>
	763	<P>x-coordinate of the left canyon wall (distance between the left
	764	canyon wall and the left border of the model domain) in
	765	m.<BR><BR>Currently, <B>canyon_wall_left</B> must be at least <I>1
	766	* <A HREF="#dx">dx</A></I> and less than <I>( <A HREF="#nx">nx</A>
	767	- 1 ) * <A HREF="#dx">dx</A> -  <A HREF="#canyon_width_x">canyon_width_x</A></I>.
	768	This parameter requires <A HREF="#topography">topography</A>
	769	= <I>'single_street_canyon'</I>.<BR><BR>The default value
	770	<B>canyon_wall_left</B> = <I>( ( <A HREF="#nx">nx</A> + 1 ) *
	771	<A HREF="#dx">dx</A> -  <A HREF="#canyon_width_x">canyon_width_x</A>
	772	) / 2</I> centers the canyon in x-direction.</P>
	773	</TD>
	774	</TR>
	775	<TR>
	776	<TD WIDTH=126>
	777	<P><A NAME="canyon_wall_south"></A><B>canyon_wall_south</B></P>
	778	</TD>
	779	<TD WIDTH=45>
	780	<P>R</P>
	781	</TD>
	782	<TD WIDTH=159>
	783	<P><I>canyon centered in y-direction</I></P>
	784	</TD>
	785	<TD WIDTH=1280>
	786	<P>y-coordinate of the South canyon wall (distance between the
	787	South canyon wall and the South border of the model domain) in
	788	m.<BR><BR>Currently, <B>canyon_wall_south</B> must be at least <I>1
	789	* <A HREF="#dy">dy</A></I> and less than <I>( <A HREF="#ny">ny</A>
	790	- 1 ) * <A HREF="#dy">dy</A> -  <A HREF="#canyon_width_y">canyon_width_y</A></I>.
	791	This parameter requires <A HREF="#topography">topography</A>
	792	= <I>'single_street_canyon'</I>.<BR><BR>The default value
	793	<B>canyon_wall_south</B> = <I>( ( <A HREF="#ny">ny</A> + 1 )
	794	* <A HREF="#dy">dy</A> -  <A HREF="#canyon_width_y">canyon_wid</A><A HREF="#canyon_width_y">th_y</A>
	795	) / 2</I> centers the canyon in y-direction.</P>
	796	</TD>
	797	</TR>
	798	<TR>
	799	<TD WIDTH=126>
	800	<P><A NAME="cloud_droplets"></A><B>cloud_droplets</B></P>
	801	</TD>
	802	<TD WIDTH=45>
	803	<P>L</P>
	804	</TD>
	805	<TD WIDTH=159>
	806	<P><I>.F.</I></P>
	807	</TD>
	808	<TD WIDTH=1280>
	809	<P>Parameter to switch on usage of cloud droplets.<BR><BR>Cloud
	810	droplets require to use particles (i.e. the NAMELIST group
	811	<FONT FACE="Courier New, Courier, monospace">particles_par</FONT>
	812	has to be included in the parameter file). Then each particle is a
	813	representative for a certain number of droplets. The droplet
	814	features (number of droplets, initial radius, etc.) can be steered
	815	with the  respective particle parameters (see e.g. <A HREF="#chapter_4.2.html#radius">radius</A>).
	816	The real number of initial droplets in a grid cell is equal to the
	817	initial number of droplets (defined by the particle source
	818	parameters <FONT FACE="Thorndale, serif"><SPAN LANG="en-GB"><A HREF="chapter_4.2.html#pst">pst</A>,
	819	<A HREF="chapter_4.2.html#psl">psl</A>, <A HREF="chapter_4.2.html#psr">psr</A>,
	820	<A HREF="chapter_4.2.html#pss">pss</A>, <A HREF="chapter_4.2.html#psn">psn</A>,
	821	<A HREF="chapter_4.2.html#psb">psb</A>, <A HREF="chapter_4.2.html#pdx">pdx</A>,
	822	<A HREF="chapter_4.2.html#pdy">pdy</A></SPAN></FONT> <FONT FACE="Thorndale, serif"><SPAN LANG="en-GB">and
	823	<A HREF="chapter_4.2.html#pdz">pdz</A></SPAN></FONT>) times the
	824	<A HREF="#initial_weighting_factor">initial_weighting_factor</A>.<BR><BR>In
	825	case of using cloud droplets, the default condensation scheme in
	826	PALM cannot be used, i.e. <A HREF="#cloud_physics">cloud_physics</A>
	827	must be set <I>.F.</I>.</P>
	828	</TD>
	829	</TR>
	830	<TR>
	831	<TD WIDTH=126>
	832	<P><A NAME="cloud_physics"></A><B>cloud_physics</B></P>
	833	</TD>
	834	<TD WIDTH=45>
	835	<P>L</P>
	836	</TD>
	837	<TD WIDTH=159>
	838	<P><I>.F.</I></P>
	839	</TD>
	840	<TD WIDTH=1280>
	841	<P>Parameter to switch on the condensation scheme.
	842	</P>
	843	<P>For <B>cloud_physics =</B> <I>.TRUE.</I>, equations for the
	844	liquid water  content and the liquid water potential
	845	temperature are solved instead of those for specific humidity and
	846	potential temperature. Note that a grid volume is assumed to be
	847	either completely saturated or completely unsaturated
	848	(0%-or-100%-scheme). A simple precipitation scheme can
	849	additionally be switched on with parameter <A HREF="#precipitation">precipitation</A>.
	850	Also cloud-top cooling by longwave radiation can be utilized (see
	851	<A HREF="#radiation">radiation</A>)<BR><B><BR>cloud_physics =</B>
	852	<I>.TRUE. </I>requires <A HREF="#humidity">humidity</A> =
	853	<I>.TRUE.</I> .<BR>Detailed information about the condensation
	854	scheme is given in the description of the <A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM-1/Dokumentationen/Cloud_physics/wolken.pdf">cloud
	855	physics module</A> (pdf-file, only in German).<BR><BR>This
	856	condensation scheme is not allowed if cloud droplets are simulated
	857	explicitly (see <A HREF="#cloud_droplets">cloud_droplets</A>).</P>
	858	</TD>
	859	</TR>
	860	<TR>
	861	<TD WIDTH=126>
	862	<P><A NAME="conserve_volume_flow"></A><B>conserve_volume_flow</B></P>
	863	</TD>
	864	<TD WIDTH=45>
	865	<P>L</P>
	866	</TD>
	867	<TD WIDTH=159>
	868	<P><I>.F.</I></P>
	869	</TD>
	870	<TD WIDTH=1280>
	871	<P>Conservation of volume flow in x- and
	872	y-direction.<BR><BR><B>conserve_volume_flow</B> = <I>.T.</I>
	873	guarantees that the volume flow through the xz- and
	874	yz-cross-sections of the total model domain remains constant
	875	throughout the run depending on the chosen
	876	<A HREF="#conserve_volume_flow_mode">conserve_volume_flow_mode</A>.<BR><BR>Note
	877	that <B>conserve_volume_flow</B> = <I>.T.</I> requires
	878	<A HREF="#dp_external">dp_external</A> = <I>.F.</I> .</P>
	879	</TD>
	880	</TR>
	881	<TR>
	882	<TD WIDTH=126>
	883	<P><A NAME="conserve_volume_flow_mode"></A><B>conserve_volume_flow_mode</B></P>
	884	</TD>
	885	<TD WIDTH=45>
	886	<P>C * 16</P>
	887	</TD>
	888	<TD WIDTH=159>
	889	<P><I>'default'</I></P>
	890	</TD>
	891	<TD WIDTH=1280>
	892	<P>Modus of volume flow conservation.<BR><BR>The following values
	893	are allowed:</P>
	894	<P STYLE="font-style: normal"><I>'default'</I>
	895	</P>
	896	<UL>
	897	<P>Per default, PALM uses <I>'initial_profiles'</I> for
	898	cyclic lateral boundary conditions (<A HREF="#bc_lr">bc_lr</A> =
	899	<I>'cyclic'</I> and <A HREF="#bc_ns">bc_ns</A> = <I>'cyclic'</I>)
	900	and <I>'inflow_profile'</I> for non-cyclic lateral boundary
	901	conditions (<A HREF="#bc_lr">bc_lr</A> /= <I>'cyclic'</I> or
	902	<A HREF="#bc_ns">bc_ns</A> /= <I>'cyclic'</I>).</P>
	903	</UL>
	904	<P><I>'initial_profiles' </I>
	905	</P>
	906	<UL>
	907	<P>The target volume flow is calculated at t=0 from the
	908	initial profiles of u and v. This setting is only allowed
	909	for cyclic lateral boundary conditions (<A HREF="#bc_lr">bc_lr</A>
	910	= <I>'cyclic'</I> and <A HREF="#bc_ns">bc_ns</A> = <I>'cyclic'</I>).</P>
	911	</UL>
	912	<P STYLE="font-style: normal"><I>'inflow_profile'</I>
	913	</P>
	914	<UL>
	915	<P>The target volume flow is calculated at every
	916	timestep from the inflow profile of u or v, respectively.
	917	This setting is only allowed for non-cyclic lateral
	918	boundary conditions (<A HREF="#bc_lr">bc_lr</A> /= <I>'cyclic'</I>
	919	or <A HREF="#bc_ns">bc_ns</A> /= <I>'cyclic'</I>).</P>
	920	</UL>
	921	<P><I>'bulk_velocity' </I>
	922	</P>
	923	<UL>
	924	<P>The target volume flow is calculated from a predefined bulk
	925	velocity (see <A HREF="#u_bulk">u_bulk</A> and <A HREF="#v_bulk">v_bulk</A>).
	926	This setting is only allowed for cyclic lateral boundary
	927	conditions (<A HREF="#bc_lr">bc_lr</A> = <I>'cyclic'</I> and
	928	<A HREF="#bc_ns">bc_ns</A> = <I>'cyclic'</I>).</P>
	929	</UL>
	930	<P>Note that <B>conserve_volume_flow_mode</B> only comes into
	931	effect if <A HREF="#conserve_volume_flow">conserve_volume_flow</A>
	932	= <I>.T. .</I>
	933	</P>
	934	</TD>
	935	</TR>
	936	<TR>
	937	<TD WIDTH=126>
	938	<P><A NAME="coupling_start_time"></A><B>coupling_start_time</B></P>
	939	</TD>
	940	<TD WIDTH=45>
	941	<P>R</P>
	942	</TD>
	943	<TD WIDTH=159>
	944	<P><I>0.0</I></P>
	945	</TD>
	946	<TD WIDTH=1280>
	947	<P>Simulation time of precursor run.</P>
	948	<P>Sets the time period a precursor run shall run uncoupled. This
	949	parameter is used to set up the precursor run control for
	950	atmosphere-ocean-<A HREF="chapter_3.8.html">coupled runs</A>. It
	951	has to be set individually to the atmospheric / oceanic precursor
	952	run. The time in the data output will show negative values during
	953	the precursor run. See <A HREF="../misc/precursor_run_control.pdf">documentation</A>
	954	for further information.</P>
	955	</TD>
	956	</TR>
	957	<TR>
	958	<TD WIDTH=126>
	959	<P><A NAME="cthf"></A><B>cthf</B></P>
	960	</TD>
	961	<TD WIDTH=45>
	962	<P>R</P>
	963	</TD>
	964	<TD WIDTH=159>
	965	<P><I>0.0</I></P>
	966	</TD>
	967	<TD WIDTH=1280>
	968	<P>Average heat flux that is prescribed at the top of the plant
	969	canopy.<BR><BR>If <A HREF="#plant_canopy">plant_canopy</A> is set
	970	<I>.T.</I>, the user can prescribe a heat flux at the top of the
	971	plant canopy.<BR>It is assumed that solar radiation penetrates the
	972	canopy and warms the foliage which, in turn, warms the air in
	973	contact with it. <BR>Note: Instead of using the value prescribed
	974	by <A HREF="#surface_heatflux">surface_heatflux</A>, the near
	975	surface heat flux is determined from an exponential function that
	976	is dependent on the cumulative leaf_area_index (Shaw and Schumann
	977	(1992, Boundary Layer Meteorol., 61, 47-64)).</P>
	978	</TD>
	979	</TR>
	980	<TR>
	981	<TD WIDTH=126>
	982	<P><A NAME="cut_spline_overshoot"></A><B>cut_spline_overshoot</B></P>
	983	</TD>
	984	<TD WIDTH=45>
	985	<P>L</P>
	986	</TD>
	987	<TD WIDTH=159>
	988	<P><I>.T.</I></P>
	989	</TD>
	990	<TD WIDTH=1280>
	991	<P>Cuts off of so-called overshoots, which can occur with the
	992	upstream-spline scheme.
	993	</P>
	994	<P><FONT COLOR="#000000">The cubic splines tend to overshoot in
	995	case of discontinuous changes of variables between neighbouring
	996	grid points.</FONT><FONT COLOR="#ff0000"> </FONT><FONT COLOR="#000000">This
	997	may lead to errors in calculating the advection tendency.</FONT>
	998	Choice of <B>cut_spline_overshoot</B> = <I>.TRUE.</I> (switched on
	999	by default) allows variable values not to exceed an interval
	1000	defined by the respective adjacent grid points. This interval can
	1001	be adjusted seperately for every prognostic variable (see
	1002	initialization parameters <A HREF="#overshoot_limit_e">overshoot_limit_e</A>,
	1003	<A HREF="#overshoot_limit_pt">overshoot_limit_pt</A>,
	1004	<A HREF="#overshoot_limit_u">overshoot_limit_u</A>, etc.). This
	1005	might be necessary in case that the default interval has a
	1006	non-tolerable effect on the model results.
	1007	</P>
	1008	<P>Overshoots may also be removed using the parameters
	1009	<A HREF="#ups_limit_e">ups_limit_e</A>, <A HREF="#ups_limit_pt">ups_limit_pt</A>,
	1010	etc. as well as by applying a long-filter (see
	1011	<A HREF="#long_filter_factor">long_filter_factor</A>).</P>
	1012	</TD>
	1013	</TR>
	1014	<TR>
	1015	<TD WIDTH=126>
	1016	<P><A NAME="damp_level_1d"></A><B>damp_level_1d</B></P>
	1017	</TD>
	1018	<TD WIDTH=45>
	1019	<P>R</P>
	1020	</TD>
	1021	<TD WIDTH=159>
	1022	<P><I>zu(nz+1)</I></P>
	1023	</TD>
	1024	<TD WIDTH=1280>
	1025	<P>Height where the damping layer begins in the 1d-model (in m).
	1026	</P>
	1027	<P>This parameter is used to switch on a damping layer for the
	1028	1d-model, which is generally needed for the damping of inertia
	1029	oscillations. Damping is done by gradually increasing the value of
	1030	the eddy diffusivities about 10% per vertical grid level (starting
	1031	with the value at the height given by <B>damp_level_1d</B>, or
	1032	possibly from the next grid pint above), i.e. K<SUB>m</SUB>(k+1) =
	1033	1.1 * K<SUB>m</SUB>(k). The values of K<SUB>m</SUB> are limited to
	1034	10 m**2/s at maximum.  <BR>This parameter only comes into
	1035	effect if the 1d-model is switched on for the initialization of
	1036	the 3d-model using <A HREF="#initializing_actions">initializing_actions</A>
	1037	= <I>'set_1d-model_profiles'</I>.
	1038	</P>
	1039	</TD>
	1040	</TR>
	1041	<TR>
	1042	<TD WIDTH=126>
	1043	<P><A NAME="dissipation_1d"></A><B>dissipation_1d</B></P>
	1044	</TD>
	1045	<TD WIDTH=45>
	1046	<P>C*20</P>
	1047	</TD>
	1048	<TD WIDTH=159>
	1049	<P><I>'as_in_3d_</I><BR><I>model'</I></P>
	1050	</TD>
	1051	<TD WIDTH=1280>
	1052	<P>Calculation method for the energy dissipation term in the TKE
	1053	equation of the 1d-model.<BR><BR>By default the dissipation is
	1054	calculated as in the 3d-model using diss = (0.19 + 0.74 * l /
	1055	l_grid) * e**1.5 / l.<BR><BR>Setting <B>dissipation_1d</B> =
	1056	<I>'detering'</I> forces the dissipation to be calculated as diss
	1057	= 0.064 * e**1.5 / l.</P>
	1058	</TD>
	1059	</TR>
	1060	<TR>
	1061	<TD WIDTH=126>
	1062	<P><A NAME="dp_external"></A><B>dp_external</B></P>
	1063	</TD>
	1064	<TD WIDTH=45>
	1065	<P>L</P>
	1066	</TD>
	1067	<TD WIDTH=159>
	1068	<P><I>.F.</I></P>
	1069	</TD>
	1070	<TD WIDTH=1280>
	1071	<P>External pressure gradient switch.<BR><BR>This parameter is
	1072	used to switch on/off an external pressure gradient as driving
	1073	force. The external pressure gradient is controlled by the
	1074	parameters <A HREF="#dp_smooth">dp_smooth</A>, <A HREF="#dp_level_b">dp_level_b</A>
	1075	and <A HREF="#dpdxy">dpdxy</A>.<BR><BR>Note that <B>dp_external</B>
	1076	= <I>.T.</I> requires <A HREF="#conserve_volume_flow">conserve_volume_flow</A>
	1077	= <I>.F. </I>It is normally recommended to disable the Coriolis
	1078	force by setting <A HREF="l#omega">omega</A> = 0.0.</P>
	1079	</TD>
	1080	</TR>
	1081	<TR>
	1082	<TD WIDTH=126>
	1083	<P><A NAME="dp_smooth"></A><B>dp_smooth</B></P>
	1084	</TD>
	1085	<TD WIDTH=45>
	1086	<P>L</P>
	1087	</TD>
	1088	<TD WIDTH=159>
	1089	<P><I>.F.</I></P>
	1090	</TD>
	1091	<TD WIDTH=1280>
	1092	<P>Vertically smooth the external pressure gradient using a
	1093	sinusoidal smoothing function.<BR><BR>This parameter only applies
	1094	if <A HREF="#dp_external">dp_external</A> = <I>.T. </I>. It is
	1095	useful in combination with <A HREF="#dp_level_b">dp_level_b</A>
	1096	>> 0 to generate a non-accelerated boundary layer well
	1097	below <A HREF="#dp_level_b">dp_level_b</A>.</P>
	1098	</TD>
	1099	</TR>
	1100	<TR>
	1101	<TD WIDTH=126>
	1102	<P><A NAME="dp_level_b"></A><B>dp_level_b</B></P>
	1103	</TD>
	1104	<TD WIDTH=45>
	1105	<P>R</P>
	1106	</TD>
	1107	<TD WIDTH=159>
	1108	<P><I>0.0</I></P>
	1109	</TD>
	1110	<TD WIDTH=1280>
	1111	<P><FONT SIZE=3>Lower limit of the vertical range for which the
	1112	external pressure gradient is applied (</FONT>in <FONT SIZE=3>m).</FONT><BR><BR>This
	1113	parameter only applies if <A HREF="#dp_external">dp_external</A> =
	1114	<I>.T. </I><SPAN LANG="en-GB">It must hold the condition zu(0) <=
	1115	</SPAN><SPAN LANG="en-GB"><B>dp_level_b</B></SPAN> <SPAN LANG="en-GB"><=
	1116	zu(<A HREF="#nz">nz</A>). </SPAN>It can be used in
	1117	combination with <A HREF="#dp_smooth">dp_smooth</A> = <I>.T.</I>
	1118	to generate a non-accelerated boundary layer well below <B>dp_level_b</B>
	1119	if <B>dp_level_b</B> >> 0.<BR><BR>Note that there is no
	1120	upper limit of the vertical range because the external pressure
	1121	gradient is always applied up to the top of the model domain.</P>
	1122	</TD>
	1123	</TR>
	1124	<TR>
	1125	<TD WIDTH=126>
	1126	<P><A NAME="dpdxy"></A><B>dpdxy</B></P>
	1127	</TD>
	1128	<TD WIDTH=45>
	1129	<P>R(2)</P>
	1130	</TD>
	1131	<TD WIDTH=159>
	1132	<P><I>2 * 0.0</I></P>
	1133	</TD>
	1134	<TD WIDTH=1280>
	1135	<P>Values of the external pressure gradient applied in x- and
	1136	y-direction, respectively (in Pa/m).<BR><BR>This parameter only
	1137	applies if <A HREF="#dp_external">dp_external</A> = <I>.T. </I>It
	1138	sets the pressure gradient values. Negative values mean an
	1139	acceleration, positive values mean deceleration. For example,
	1140	<B>dpdxy</B> = -0.0002, 0.0, drives the flow in positive
	1141	x-direction,
	1142	</P>
	1143	</TD>
	1144	</TR>
	1145	<TR>
	1146	<TD WIDTH=126>
	1147	<P><A NAME="drag_coefficient"></A><B>drag_coefficient</B></P>
	1148	</TD>
	1149	<TD WIDTH=45>
	1150	<P>R</P>
	1151	</TD>
	1152	<TD WIDTH=159>
	1153	<P><I>0.0</I></P>
	1154	</TD>
	1155	<TD WIDTH=1280>
	1156	<P>Drag coefficient used in the plant canopy model.<BR><BR>This
	1157	parameter has to be non-zero, if the parameter <A HREF="#plant_canopy">plant_canopy</A>
	1158	is set <I>.T.</I>.</P>
	1159	</TD>
	1160	</TR>
	1161	<TR>
	1162	<TD WIDTH=126>
	1163	<P><A NAME="dt"></A><B>dt</B></P>
	1164	</TD>
	1165	<TD WIDTH=45>
	1166	<P>R</P>
	1167	</TD>
	1168	<TD WIDTH=159>
	1169	<P><I>variable</I></P>
	1170	</TD>
	1171	<TD WIDTH=1280>
	1172	<P>Time step for the 3d-model (in s).
	1173	</P>
	1174	<P>By default, (i.e. if a Runge-Kutta scheme is used, see
	1175	<A HREF="#timestep_scheme">timestep_scheme</A>) the value of the
	1176	time step is calculating after each time step (following the time
	1177	step criteria) and used for the next step.</P>
	1178	<P>If the user assigns <B>dt</B> a value, then the time step is
	1179	fixed to this value throughout the whole run (whether it fulfills
	1180	the time step criteria or not). However, changes are allowed for
	1181	restart runs, because <B>dt</B> can also be used as a <A HREF="chapter_4.2.html#dt_laufparameter">run
	1182	parameter</A>.
	1183	</P>
	1184	<P>In case that the calculated time step meets the condition</P>
	1185	<UL>
	1186	<P><B>dt</B> < 0.00001 * <A HREF="chapter_4.2.html#dt_max">dt_max</A>
	1187	(with dt_max = 20.0)</P>
	1188	</UL>
	1189	<P>the simulation will be aborted. Such situations usually arise
	1190	in case of any numerical problem / instability which causes a
	1191	non-realistic increase of the wind speed.
	1192	</P>
	1193	<P>A small time step due to a large mean horizontal windspeed
	1194	speed may be enlarged by using a coordinate transformation (see
	1195	<A HREF="#galilei_transformation">galilei_transformation</A>), in
	1196	order to spare CPU time.</P>
	1197	<P>If the leapfrog timestep scheme is used (see <A HREF="#timestep_scheme">timestep_scheme</A>)
	1198	a temporary time step value dt_new is calculated first, with
	1199	dt_new = <A HREF="chapter_4.2.html#fcl_factor">cfl_factor</A> *
	1200	dt_crit where dt_crit is the maximum timestep allowed by the CFL
	1201	and diffusion condition. Next it is examined whether dt_new
	1202	exceeds or falls below the value of the previous timestep by at
	1203	least +5 % / -2%. If it is smaller, <B>dt</B> = dt_new is
	1204	immediately used for the next timestep. If it is larger, then <B>dt
	1205	</B>= 1.02 * dt_prev (previous timestep) is used as the new
	1206	timestep, however the time step is only increased if the last
	1207	change of the time step is dated back at least 30 iterations. If
	1208	dt_new is located in the interval mentioned above, then dt does
	1209	not change at all. By doing so, permanent time step changes as
	1210	well as large sudden changes (increases) in the time step are
	1211	avoided.</P>
	1212	</TD>
	1213	</TR>
	1214	<TR>
	1215	<TD WIDTH=126>
	1216	<P><A NAME="dt_pr_1d"></A><B>dt_pr_1d</B></P>
	1217	</TD>
	1218	<TD WIDTH=45>
	1219	<P>R</P>
	1220	</TD>
	1221	<TD WIDTH=159>
	1222	<P><I>9999999.9</I></P>
	1223	</TD>
	1224	<TD WIDTH=1280>
	1225	<P>Temporal interval of vertical profile output of the 1D-model
	1226	(in s).
	1227	</P>
	1228	<P>Data are written in ASCII format to file <A HREF="chapter_3.4.html#LIST_PROFIL_1D">LIST_PROFIL_1D</A>.
	1229	This parameter is only in effect if the 1d-model has been switched
	1230	on for the initialization of the 3d-model with
	1231	<A HREF="#initializing_actions">initializing_actions</A> =
	1232	<I>'set_1d-model_profiles'</I>.</P>
	1233	</TD>
	1234	</TR>
	1235	<TR>
	1236	<TD WIDTH=126>
	1237	<P><A NAME="dt_run_control_1d"></A><B>dt_run_control_1d</B></P>
	1238	</TD>
	1239	<TD WIDTH=45>
	1240	<P>R</P>
	1241	</TD>
	1242	<TD WIDTH=159>
	1243	<P><I>60.0</I></P>
	1244	</TD>
	1245	<TD WIDTH=1280>
	1246	<P>Temporal interval of runtime control output of the 1d-model (in
	1247	s).
	1248	</P>
	1249	<P>Data are written in ASCII format to file <A HREF="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</A>.
	1250	This parameter is only in effect if the 1d-model is switched on
	1251	for the initialization of the 3d-model with <A HREF="#initializing_actions">initializing_actions</A>
	1252	= <I>'set_1d-model_profiles'</I>.</P>
	1253	</TD>
	1254	</TR>
	1255	<TR>
	1256	<TD WIDTH=126>
	1257	<P><A NAME="dx"></A><B>dx</B></P>
	1258	</TD>
	1259	<TD WIDTH=45>
	1260	<P>R</P>
	1261	</TD>
	1262	<TD WIDTH=159>
	1263	<P><I>1.0</I></P>
	1264	</TD>
	1265	<TD WIDTH=1280>
	1266	<P>Horizontal grid spacing along the x-direction (in m).
	1267	</P>
	1268	<P>Along x-direction only a constant grid spacing is allowed.</P>
	1269	<P>For <A HREF="chapter_3.8.html">coupled runs</A> this parameter
	1270	must be equal in both parameter files <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN</FONT></A>
	1271	and <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN_O</FONT></A>.</P>
	1272	</TD>
	1273	</TR>
	1274	<TR>
	1275	<TD WIDTH=126>
	1276	<P><A NAME="dy"></A><B>dy</B></P>
	1277	</TD>
	1278	<TD WIDTH=45>
	1279	<P>R</P>
	1280	</TD>
	1281	<TD WIDTH=159>
	1282	<P><I>1.0</I></P>
	1283	</TD>
	1284	<TD WIDTH=1280>
	1285	<P>Horizontal grid spacing along the y-direction (in m).
	1286	</P>
	1287	<P>Along y-direction only a constant grid spacing is allowed.</P>
	1288	<P>For <A HREF="chapter_3.8.html">coupled runs</A> this parameter
	1289	must be equal in both parameter files <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN</FONT></A>
	1290	and <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN_O</FONT></A>.</P>
	1291	</TD>
	1292	</TR>
	1293	<TR>
	1294	<TD WIDTH=126>
	1295	<P><A NAME="dz"></A><B>dz</B></P>
	1296	</TD>
	1297	<TD WIDTH=45>
	1298	<P>R</P>
	1299	</TD>
	1300	<TD WIDTH=159>
	1301	<P><BR>
	1302	</P>
	1303	</TD>
	1304	<TD WIDTH=1280>
	1305	<P>Vertical grid spacing (in m).
	1306	</P>
	1307	<P>This parameter must be assigned by the user, because no default
	1308	value is given.</P>
	1309	<P>By default, the model uses constant grid spacing along
	1310	z-direction, but it can be stretched using the parameters
	1311	<A HREF="#dz_stretch_level">dz_stretch_level</A> and
	1312	<A HREF="#dz_stretch_factor">dz_stretch_factor</A>. In case of
	1313	stretching, a maximum allowed grid spacing can be given by <A HREF="#dz_max">dz_max</A>.</P>
	1314	<P>Assuming a constant <B>dz</B>, the scalar levels (zu) are
	1315	calculated directly by:
	1316	</P>
	1317	<UL>
	1318	<P>zu(0) = - dz * 0.5  <BR>zu(1) = dz * 0.5</P>
	1319	</UL>
	1320	<P>The w-levels lie half between them:
	1321	</P>
	1322	<UL>
	1323	<P>zw(k) = ( zu(k) + zu(k+1) ) * 0.5</P>
	1324	</UL>
	1325	</TD>
	1326	</TR>
	1327	<TR>
	1328	<TD WIDTH=126>
	1329	<P><A NAME="dz_max"></A><B>dz_max</B></P>
	1330	</TD>
	1331	<TD WIDTH=45>
	1332	<P>R</P>
	1333	</TD>
	1334	<TD WIDTH=159>
	1335	<P><I>9999999.9</I></P>
	1336	</TD>
	1337	<TD WIDTH=1280>
	1338	<P>Allowed maximum vertical grid spacing (in m).<BR><BR>If the
	1339	vertical grid is stretched (see <A HREF="#dz_stretch_factor">dz_stretch_factor</A>
	1340	and <A HREF="#dz_stretch_level">dz_stretch_level</A>), <B>dz_max</B>
	1341	can be used to limit the vertical grid spacing.</P>
	1342	</TD>
	1343	</TR>
	1344	<TR>
	1345	<TD WIDTH=126>
	1346	<P><A NAME="dz_stretch_factor"></A><B>dz_stretch_factor</B></P>
	1347	</TD>
	1348	<TD WIDTH=45>
	1349	<P>R</P>
	1350	</TD>
	1351	<TD WIDTH=159>
	1352	<P><I>1.08</I></P>
	1353	</TD>
	1354	<TD WIDTH=1280>
	1355	<P>Stretch factor for a vertically stretched grid (see
	1356	<A HREF="#dz_stretch_level">dz_stretch_level</A>).
	1357	</P>
	1358	<P>The stretch factor should not exceed a value of approx. 1.10 -
	1359	1.12, otherwise the discretization errors due to the stretched
	1360	grid not negligible any more. (refer Kalnay de Rivas)</P>
	1361	</TD>
	1362	</TR>
	1363	<TR>
	1364	<TD WIDTH=126>
	1365	<P><A NAME="dz_stretch_level"></A><B>dz_stretch_level</B></P>
	1366	</TD>
	1367	<TD WIDTH=45>
	1368	<P>R</P>
	1369	</TD>
	1370	<TD WIDTH=159>
	1371	<P><I>100000.0</I></P>
	1372	</TD>
	1373	<TD WIDTH=1280>
	1374	<P>Height level above/below which the grid is to be stretched
	1375	vertically (in m).
	1376	</P>
	1377	<P>For <A HREF="#ocean">ocean</A> = .F., <B>dz_stretch_level </B>is
	1378	the height level (in m) <B>above </B>which the grid is to be
	1379	stretched vertically. The vertical grid spacings <A HREF="#dz">dz</A>
	1380	above this level are calculated as
	1381	</P>
	1382	<UL>
	1383	<P><B>dz</B>(k+1) = <B>dz</B>(k) * <A HREF="#dz_stretch_factor">dz_stretch_factor</A></P>
	1384	</UL>
	1385	<P>and used as spacings for the scalar levels (zu). The w-levels
	1386	are then defined as:
	1387	</P>
	1388	<UL>
	1389	<P>zw(k) = ( zu(k) + zu(k+1) ) * 0.5.
	1390	</P>
	1391	</UL>
	1392	<P>For <A HREF="#ocean">ocean</A> = .T., <B>dz_stretch_level </B>is
	1393	the height level (in m, negative) <B>below</B> which the grid is
	1394	to be stretched vertically. The vertical grid spacings <A HREF="#dz">dz</A>
	1395	below this level are calculated correspondingly as
	1396	</P>
	1397	<UL>
	1398	<P><B>dz</B>(k-1) = <B>dz</B>(k) * <A HREF="#dz_stretch_factor">dz_stretch_factor</A>.</P>
	1399	</UL>
	1400	</TD>
	1401	</TR>
	1402	<TR>
	1403	<TD WIDTH=126>
	1404	<P><A NAME="e_init"></A><B>e_init</B></P>
	1405	</TD>
	1406	<TD WIDTH=45>
	1407	<P>R</P>
	1408	</TD>
	1409	<TD WIDTH=159>
	1410	<P><I>0.0</I></P>
	1411	</TD>
	1412	<TD WIDTH=1280>
	1413	<P>Initial subgrid-scale TKE in m<SUP>2</SUP>s<SUP>-2</SUP>.<BR><BR>This
	1414	option prescribes an initial subgrid-scale TKE from which the
	1415	initial diffusion coefficients K<SUB>m</SUB> and K<SUB>h</SUB>
	1416	will be calculated if <B>e_init</B> is positive. This option only
	1417	has an effect if <A HREF="#km_constant">km_constant</A> is
	1418	not set.</P>
	1419	</TD>
	1420	</TR>
	1421	<TR>
	1422	<TD WIDTH=126>
	1423	<P><A NAME="e_min"></A><B>e_min</B></P>
	1424	</TD>
	1425	<TD WIDTH=45>
	1426	<P>R</P>
	1427	</TD>
	1428	<TD WIDTH=159>
	1429	<P><I>0.0</I></P>
	1430	</TD>
	1431	<TD WIDTH=1280>
	1432	<P>Minimum subgrid-scale TKE in m<SUP>2</SUP>s<SUP>-2</SUP>.<BR><BR>This
	1433	option adds artificial viscosity to the flow by ensuring that
	1434	the subgrid-scale TKE does not fall below the minimum threshold
	1435	<B>e_min</B>.</P>
	1436	</TD>
	1437	</TR>
	1438	<TR>
	1439	<TD WIDTH=126>
	1440	<P><A NAME="end_time_1d"></A><B>end_time_1d</B></P>
	1441	</TD>
	1442	<TD WIDTH=45>
	1443	<P>R</P>
	1444	</TD>
	1445	<TD WIDTH=159>
	1446	<P><I>864000.0</I></P>
	1447	</TD>
	1448	<TD WIDTH=1280>
	1449	<P>Time to be simulated for the 1d-model (in s).
	1450	</P>
	1451	<P>The default value corresponds to a simulated time of 10 days.
	1452	Usually, after such a period the inertia oscillations have
	1453	completely decayed and the solution of the 1d-model can be
	1454	regarded as stationary (see <A HREF="#damp_level_1d">damp_level_1d</A>).
	1455	This parameter is only in effect if the 1d-model is switched on
	1456	for the initialization of the 3d-model with <A HREF="#initializing_actions">initializing_actions</A>
	1457	= <I>'set_1d-model_profiles'</I>.</P>
	1458	</TD>
	1459	</TR>
	1460	<TR>
	1461	<TD WIDTH=126>
	1462	<P><A NAME="fft_method"></A><B>fft_method</B></P>
	1463	</TD>
	1464	<TD WIDTH=45>
	1465	<P>C * 20</P>
	1466	</TD>
	1467	<TD WIDTH=159>
	1468	<P><I>'system-</I><BR><I>specific'</I></P>
	1469	</TD>
	1470	<TD WIDTH=1280>
	1471	<P>FFT-method to be used.</P>
	1472	<P><BR>The fast fourier transformation (FFT) is used for solving
	1473	the perturbation pressure equation with a direct method (see
	1474	<A HREF="chapter_4.2.html#psolver">psolver</A>) and for
	1475	calculating power spectra (see optional software packages, section
	1476	<A HREF="chapter_4.2.html#spectra_package">4.2</A>).</P>
	1477	<P><BR>By default, system-specific, optimized routines from
	1478	external vendor libraries are used. However, these are available
	1479	only on certain computers and there are more or less severe
	1480	restrictions concerning the number of gridpoints to be used with
	1481	them.</P>
	1482	<P>There are two other PALM internal methods available on every
	1483	machine (their respective source code is part of the PALM source
	1484	code):</P>
	1485	<P>1.: The <B>Temperton</B>-method from Clive Temperton (ECWMF)
	1486	which is computationally very fast and switched on with <B>fft_method</B>
	1487	= <I>'temperton-algorithm'</I>. The number of horizontal
	1488	gridpoints (nx+1, ny+1) to be used with this method must be
	1489	composed of prime factors 2, 3 and 5.</P>
	1490	<P>2.: The <B>Singleton</B>-method which is very slow but has no
	1491	restrictions concerning the number of gridpoints to be used with,
	1492	switched on with <B>fft_method</B> = <I>'singleton-algorithm'</I>.
	1493	</P>
	1494	</TD>
	1495	</TR>
	1496	<TR>
	1497	<TD WIDTH=126>
	1498	<P><A NAME="galilei_transformation"></A><B>galilei_transformation</B></P>
	1499	</TD>
	1500	<TD WIDTH=45>
	1501	<P>L</P>
	1502	</TD>
	1503	<TD WIDTH=159>
	1504	<P><I>.F.</I></P>
	1505	</TD>
	1506	<TD WIDTH=1280>
	1507	<P>Application of a Galilei-transformation to the coordinate
	1508	system of the model.</P>
	1509	<P>With <B>galilei_transformation</B> = <I>.T.,</I> a so-called
	1510	Galilei-transformation is switched on which ensures that the
	1511	coordinate system of the model is moved along with the
	1512	geostrophical wind. Alternatively, the model domain can be moved
	1513	along with the averaged horizontal wind (see
	1514	<A HREF="#use_ug_for_galilei_tr">use_ug_for_galilei_tr</A>, this
	1515	can and will naturally change in time). With this method,
	1516	numerical inaccuracies of the Piascek - Williams - scheme
	1517	(concerns in particular the momentum advection) are minimized.
	1518	Beyond that, in the majority of cases the lower relative
	1519	velocities in the moved system permit a larger time step (<A HREF="#dt">dt</A>).
	1520	Switching the transformation on is only worthwhile if the
	1521	geostrophical wind (ug, vg) and the averaged horizontal wind
	1522	clearly deviate from the value 0. In each case, the distance the
	1523	coordinate system has been moved is written to the file
	1524	<A HREF="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</A>.
	1525	</P>
	1526	<P>Non-cyclic lateral boundary conditions (see <A HREF="#bc_lr">bc_lr</A>
	1527	and <A HREF="#bc_ns">bc_ns</A>), the specification of a gestrophic
	1528	wind that is not constant with height as well as e.g. stationary
	1529	inhomogeneities at the bottom boundary do not allow the use of
	1530	this transformation.</P>
	1531	</TD>
	1532	</TR>
	1533	<TR>
	1534	<TD WIDTH=126>
	1535	<P><A NAME="grid_matching"></A><B>grid_matching</B></P>
	1536	</TD>
	1537	<TD WIDTH=45>
	1538	<P>C * 6</P>
	1539	</TD>
	1540	<TD WIDTH=159>
	1541	<P><I>'strict'</I></P>
	1542	</TD>
	1543	<TD WIDTH=1280>
	1544	<P>Variable to adjust the subdomain sizes in parallel runs.<BR><BR>For
	1545	<B>grid_matching</B> = <I>'strict'</I>, the subdomains are forced
	1546	to have an identical size on all processors. In this case the
	1547	processor numbers in the respective directions of the virtual
	1548	processor net must fulfill certain divisor conditions concerning
	1549	the grid point numbers in the three directions (see <A HREF="#nx">nx</A>,
	1550	<A HREF="#ny">ny</A> and <A HREF="#nz">nz</A>). Advantage of this
	1551	method is that all PEs bear the same computational load.<BR><BR>There
	1552	is no such restriction by default, because then smaller subdomains
	1553	are allowed on those processors which form the right and/or north
	1554	boundary of the virtual processor grid. On all other processors
	1555	the subdomains are of same size. Whether smaller subdomains are
	1556	actually used, depends on the number of processors and the grid
	1557	point numbers used. Information about the respective settings are
	1558	given in file <A HREF="../../../../../../raasch/public_html/PALM_group/home/raasch/public_html/PALM_group/doc/app/chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</A>.<BR><BR>When
	1559	using a multi-grid method for solving the Poisson equation (see
	1560	<A HREF="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">psolver</A>)
	1561	only <B>grid_matching</B> = <I>'strict'</I> is allowed.<BR><BR><B>Note:</B><BR>In
	1562	some cases for small processor numbers there may be a very bad
	1563	load balancing among the processors which may reduce the
	1564	performance of the code.</P>
	1565	</TD>
	1566	</TR>
	1567	<TR>
	1568	<TD WIDTH=126>
	1569	<P><A NAME="humidity"></A><B>humidity</B></P>
	1570	</TD>
	1571	<TD WIDTH=45>
	1572	<P>L</P>
	1573	</TD>
	1574	<TD WIDTH=159>
	1575	<P><I>.F.</I></P>
	1576	</TD>
	1577	<TD WIDTH=1280>
	1578	<P>Parameter to switch on the prognostic equation for specific
	1579	humidity q.</P>
	1580	<P>The initial vertical profile of q can be set via parameters
	1581	<A HREF="#q_surface">q_surface</A>, <A HREF="#q_vertical_gradient">q_vertical_gradient</A>
	1582	and <A HREF="#q_vertical_gradient_level">q_vertical_gradient_level</A>.
	1583	Boundary conditions can be set via <A HREF="#q_surface_initial_change">q_surface_initial_change</A>
	1584	and <A HREF="#surface_waterflux">surface_waterflux</A>.</P>
	1585	<P>If the condensation scheme is switched on (<A HREF="#cloud_physics">cloud_physics</A>
	1586	= .TRUE.), q becomes the total liquid water content (sum of
	1587	specific humidity and liquid water content).</P>
	1588	</TD>
	1589	</TR>
	1590	<TR>
	1591	<TD WIDTH=126>
	1592	<P><A NAME="inflow_damping_height"></A><B>inflow_damping_height</B></P>
	1593	</TD>
	1594	<TD WIDTH=45>
	1595	<P>R</P>
	1596	</TD>
	1597	<TD WIDTH=159>
	1598	<P><I>from precursor run</I></P>
	1599	</TD>
	1600	<TD WIDTH=1280>
	1601	<P>Height below which the turbulence signal is used for turbulence
	1602	recycling (in m).<BR><BR>In case of a turbulent inflow (see
	1603	<A HREF="#turbulent_inflow">turbulent_inflow</A>), this parameter
	1604	defines the vertical thickness of the turbulent layer up to which
	1605	the turbulence extracted at the recycling plane (see
	1606	<A HREF="#recycling_width">recycling_width</A>) shall be imposed
	1607	to the inflow. Above this level the turbulence signal is linearly
	1608	damped to zero. The transition range within which the signal falls
	1609	to zero is given by the parameter <A HREF="#inflow_damping_width">inflow_damping_width</A>.<BR><BR>By
	1610	default, this height is set as the height of the convective
	1611	boundary layer as calculated from a precursor run. See <A HREF="chapter_3.9.html">chapter
	1612	3.9</A> about proper settings for getting this CBL height from a
	1613	precursor run.
	1614	</P>
	1615	</TD>
	1616	</TR>
	1617	<TR>
	1618	<TD WIDTH=126>
	1619	<P><A NAME="inflow_damping_width"></A><B>inflow_damping_width</B></P>
	1620	</TD>
	1621	<TD WIDTH=45>
	1622	<P>R</P>
	1623	</TD>
	1624	<TD WIDTH=159>
	1625	<P><I>0.1 * <A HREF="#inflow_damping_height">inflow_damping</A></I><A HREF="#inflow_damping_height"><BR><I>_height</I></A></P>
	1626	</TD>
	1627	<TD WIDTH=1280>
	1628	<P>Transition range within which the turbulance signal is damped
	1629	to zero (in m).<BR><BR>See <A HREF="#inflow_damping_height">inflow_damping_height</A>
	1630	for explanation.</P>
	1631	</TD>
	1632	</TR>
	1633	<TR>
	1634	<TD WIDTH=126>
	1635	<P><A NAME="inflow_disturbance_begin"></A><B>inflow_disturbance_<BR>begin</B></P>
	1636	</TD>
	1637	<TD WIDTH=45>
	1638	<P>I</P>
	1639	</TD>
	1640	<TD WIDTH=159>
	1641	<P><I>MIN(10,</I><BR><I>nx/2 or ny/2)</I></P>
	1642	</TD>
	1643	<TD WIDTH=1280>
	1644	<P>Lower limit of the horizontal range for which random
	1645	perturbations are to be imposed on the horizontal velocity field
	1646	(gridpoints).<BR><BR>If non-cyclic lateral boundary conditions are
	1647	used (see <A HREF="#bc_lr">bc_lr</A> or <A HREF="#bc_ns">bc_ns</A>),
	1648	this parameter gives the gridpoint number (counted horizontally
	1649	from the inflow)  from which on perturbations are imposed on
	1650	the horizontal velocity field. Perturbations must be switched on
	1651	with parameter <A HREF="chapter_4.2.html#create_disturbances">create_disturbances</A>.</P>
	1652	</TD>
	1653	</TR>
	1654	<TR>
	1655	<TD WIDTH=126>
	1656	<P><A NAME="inflow_disturbance_end"></A><B>inflow_disturbance_<BR>end</B></P>
	1657	</TD>
	1658	<TD WIDTH=45>
	1659	<P>I</P>
	1660	</TD>
	1661	<TD WIDTH=159>
	1662	<P><I>MIN(100,</I><BR><I>3/4nx or</I><BR><I>3/4ny)</I></P>
	1663	</TD>
	1664	<TD WIDTH=1280>
	1665	<P>Upper limit of the horizontal range for which random
	1666	perturbations are to be imposed on the horizontal velocity field
	1667	(gridpoints).<BR><BR>If non-cyclic lateral boundary conditions are
	1668	used (see <A HREF="#bc_lr">bc_lr</A> or <A HREF="#bc_ns">bc_ns</A>),
	1669	this parameter gives the gridpoint number (counted horizontally
	1670	from the inflow)  unto which perturbations are imposed on the
	1671	horizontal velocity field. Perturbations must be switched on with
	1672	parameter <A HREF="chapter_4.2.html#create_disturbances">create_disturbances</A>.</P>
	1673	</TD>
	1674	</TR>
	1675	<TR>
	1676	<TD WIDTH=126>
	1677	<P><A NAME="initializing_actions"></A><B>initializing_actions</B></P>
	1678	</TD>
	1679	<TD WIDTH=45>
	1680	<P>C * 100</P>
	1681	</TD>
	1682	<TD WIDTH=159>
	1683	<P><BR>
	1684	</P>
	1685	</TD>
	1686	<TD WIDTH=1280>
	1687	<P STYLE="font-style: normal">Initialization actions to be carried
	1688	out.
	1689	</P>
	1690	<P STYLE="font-style: normal">This parameter does not have a
	1691	default value and therefore must be assigned with each model run.
	1692	For restart runs <B>initializing_actions</B> = <I>'read_restart_data'</I>
	1693	must be set. For the initial run of a job chain the following
	1694	values are allowed:
	1695	</P>
	1696	<P STYLE="font-style: normal"><I>'set_constant_profiles'</I>
	1697	</P>
	1698	<UL>
	1699	<P>A horizontal wind profile consisting of linear sections (see
	1700	<A HREF="#ug_surface">ug_surface</A>, <A HREF="#ug_vertical_gradient">ug_vertical_gradient</A>,
	1701	<A HREF="#ug_vertical_gradient_level">ug_vertical_gradient_level</A>
	1702	and <A HREF="#vg_surface">vg_surface</A>, <A HREF="#vg_vertical_gradient">vg_vertical_gradient</A>,
	1703	<A HREF="#vg_vertical_gradient_level">vg_vertical_gradient_level</A>,
	1704	respectively) as well as a vertical temperature (humidity)
	1705	profile consisting of linear sections (see <A HREF="#pt_surface">pt_surface</A>,
	1706	<A HREF="#pt_vertical_gradient">pt_vertical_gradient</A>,
	1707	<A HREF="#q_surface">q_surface</A> and <A HREF="#q_vertical_gradient">q_vertical_gradient</A>)
	1708	are assumed as initial profiles. The subgrid-scale TKE is set to
	1709	0 but K<SUB>m</SUB> and K<SUB>h</SUB> are set to very small
	1710	values because otherwise no TKE would be generated.</P>
	1711	</UL>
	1712	<P><I>'set_1d-model_profiles' </I>
	1713	</P>
	1714	<UL>
	1715	<P>The arrays of the 3d-model are initialized with the
	1716	(stationary) solution of the 1d-model. These are the variables e,
	1717	kh, km, u, v and with Prandtl layer switched on rif, us, usws,
	1718	vsws. The temperature (humidity) profile consisting of linear
	1719	sections is set as for 'set_constant_profiles' and assumed as
	1720	constant in time within the 1d-model. For steering of the
	1721	1d-model a set of parameters with suffix "_1d" (e.g.
	1722	<A HREF="#end_time_1d">end_time_1d</A>, <A HREF="#damp_level_1d">damp_level_1d</A>)
	1723	is available.</P>
	1724	</UL>
	1725	<P><I>'by_user'</I></P>
	1726	<P STYLE="margin-left: 0.42in">The initialization of the arrays of
	1727	the 3d-model is under complete control of the user and has to be
	1728	done in routine <A HREF="chapter_3.5.1.html#user_init_3d_model">user_init_3d_model</A>
	1729	of the user-interface.</P>
	1730	<P><I>'initialize_vortex'</I>
	1731	</P>
	1732	<P STYLE="margin-left: 0.42in">The initial velocity field of the
	1733	3d-model corresponds to a Rankine-vortex with vertical axis. This
	1734	setting may be used to test advection schemes. Free-slip boundary
	1735	conditions for u and v (see <A HREF="#bc_uv_b">bc_uv_b</A>,
	1736	<A HREF="#bc_uv_t">bc_uv_t</A>) are necessary. In order not to
	1737	distort the vortex, an initial horizontal wind profile constant
	1738	with height is necessary (to be set by <B>initializing_actions</B>
	1739	= <I>'set_constant_profiles'</I>) and some other conditions have
	1740	to be met (neutral stratification, diffusion must be switched off,
	1741	see <A HREF="#km_constant">km_constant</A>). The center of the
	1742	vortex is located at jc = (nx+1)/2. It extends from k = 0 to k =
	1743	nz+1. Its radius is 8 * <A HREF="#dx">dx</A> and the exponentially
	1744	decaying part ranges to 32 * <A HREF="#dx">dx</A> (see
	1745	init_rankine.f90).
	1746	</P>
	1747	<P><I>'initialize_ptanom'</I>
	1748	</P>
	1749	<UL>
	1750	<P>A 2d-Gauss-like shape disturbance (x,y) is added to the
	1751	initial temperature field with radius 10.0 * <A HREF="#dx">dx</A>
	1752	and center at jc = (nx+1)/2. This may be used for tests of scalar
	1753	advection schemes (see <A HREF="#scalar_advec">scalar_advec</A>).
	1754	Such tests require a horizontal wind profile constant with hight
	1755	and diffusion switched off (see <I>'initialize_vortex'</I>).
	1756	Additionally, the buoyancy term must be switched of in the
	1757	equation of motion  for w (this requires the user to comment
	1758	out the call of <FONT FACE="monospace">buoyancy</FONT> in the
	1759	source code of <FONT FACE="monospace">prognostic_equations.f90</FONT>).</P>
	1760	</UL>
	1761	<P><I>'cyclic_fill'</I></P>
	1762	<P STYLE="margin-left: 0.42in"><SPAN STYLE="font-style: normal">Here,
	1763	3d-data from a precursor run are read by the initial (main) run.
	1764	The precursor run is allowed to have a smaller domain along x and
	1765	y compared with the main run. Also, different numbers of
	1766	processors can be used for these two runs. Limitations are that
	1767	the precursor run must use cyclic horizontal boundary conditions
	1768	and that the number of vertical grid points, <A HREF="#nz">nz</A>,
	1769	must be same for the precursor run and the main run. If the total
	1770	domain of the main run is larger than that of the precursor run,
	1771	the domain is filled by cyclic repetition of the (cyclic)
	1772	precursor data. This initialization method is recommended if a
	1773	turbulent inflow is used (see <A HREF="#turbulent_inflow">turbulent_inflow</A>).
	1774	3d-data must be made available to the run by activating an
	1775	appropriate file connection statement for local file BININ. See
	1776	<A HREF="chapter_3.9.html">chapter 3.9</A> for more details, where
	1777	usage of a turbulent inflow is explained. </SPAN>
	1778	</P>
	1779	<P STYLE="font-style: normal">Values may be combined, e.g.
	1780	<B>initializing_actions</B> = <I>'set_constant_profiles
	1781	initialize_vortex'</I>, but the values of <I>'set_constant_profiles'</I>,
	1782	<I>'set_1d-model_profiles'</I> , and <I>'by_user'</I> must not be
	1783	given at the same time.</P>
	1784	</TD>
	1785	</TR>
	1786	<TR>
	1787	<TD WIDTH=126>
	1788	<P><A NAME="km_constant"></A><B>km_constant</B></P>
	1789	</TD>
	1790	<TD WIDTH=45>
	1791	<P>R</P>
	1792	</TD>
	1793	<TD WIDTH=159>
	1794	<P><I>variable<BR>(computed from TKE)</I></P>
	1795	</TD>
	1796	<TD WIDTH=1280>
	1797	<P>Constant eddy diffusivities are used (laminar simulations).
	1798	</P>
	1799	<P>If this parameter is specified, both in the 1d and in the
	1800	3d-model constant values for the eddy diffusivities are used in
	1801	space and time with K<SUB>m</SUB> = <B>km_constant</B> and K<SUB>h</SUB>
	1802	= K<SUB>m</SUB> / <A HREF="chapter_4.2.html#prandtl_number">prandtl_number</A>.
	1803	The prognostic equation for the subgrid-scale TKE is switched off.
	1804	Constant eddy diffusivities are only allowed with the Prandtl
	1805	layer (<A HREF="#prandtl_layer">prandtl_layer</A>) switched off.</P>
	1806	</TD>
	1807	</TR>
	1808	<TR>
	1809	<TD WIDTH=126>
	1810	<P><A NAME="km_damp_max"></A><B>km_damp_max</B></P>
	1811	</TD>
	1812	<TD WIDTH=45>
	1813	<P>R</P>
	1814	</TD>
	1815	<TD WIDTH=159>
	1816	<P><I>0.5*(dx or dy)</I></P>
	1817	</TD>
	1818	<TD WIDTH=1280>
	1819	<P>Maximum diffusivity used for filtering the velocity field in
	1820	the vicinity of the outflow (in m<SUP>2</SUP>/s).<BR><BR>When
	1821	using non-cyclic lateral boundaries (see <A HREF="#bc_lr">bc_lr</A>
	1822	or <A HREF="#bc_ns">bc_ns</A>), a smoothing has to be applied to
	1823	the velocity field in the vicinity of the outflow in order to
	1824	suppress any reflections of outgoing disturbances. Smoothing is
	1825	done by increasing the eddy diffusivity along the horizontal
	1826	direction which is perpendicular to the outflow boundary. Only
	1827	velocity components parallel to the outflow boundary are filtered
	1828	(e.g. v and w, if the outflow is along x). Damping is applied from
	1829	the bottom to the top of the domain.<BR><BR>The horizontal range
	1830	of the smoothing is controlled by <A HREF="#outflow_damping_width">outflow_damping_width</A>
	1831	which defines the number of gridpoints (counted from the outflow
	1832	boundary) from where on the smoothing is applied. Starting from
	1833	that point, the eddy diffusivity is linearly increased (from zero
	1834	to its maximum value given by <B>km_damp_max</B>) until half of
	1835	the damping range width, from where it remains constant up to the
	1836	outflow boundary. If at a certain grid point the eddy diffusivity
	1837	calculated from the flow field is larger than as described above,
	1838	it is used instead.<BR><BR>The default value of <B>km_damp_max</B>
	1839	has been empirically proven to be sufficient.</P>
	1840	</TD>
	1841	</TR>
	1842	<TR>
	1843	<TD WIDTH=126>
	1844	<P><A NAME="lad_surface"></A><B>lad_surface</B></P>
	1845	</TD>
	1846	<TD WIDTH=45>
	1847	<P>R</P>
	1848	</TD>
	1849	<TD WIDTH=159>
	1850	<P><I>0.0</I></P>
	1851	</TD>
	1852	<TD WIDTH=1280>
	1853	<P>Surface value of the leaf area density (in m<SUP>2</SUP>/m<SUP>3</SUP>).<BR><BR>This
	1854	parameter assigns the value of the leaf area density <B>lad</B> at
	1855	the surface (k=0)<B>.</B> Starting from this value, the leaf area
	1856	density profile is constructed with <A HREF="#lad_vertical_gradient">lad_vertical_gradient</A>
	1857	and <A HREF="#lad_vertical_gradient_level">lad_vertical_gradient_level
	1858	</A>.</P>
	1859	</TD>
	1860	</TR>
	1861	<TR>
	1862	<TD WIDTH=126>
	1863	<P><A NAME="lad_vertical_gradient"></A><B>lad_vertical_gradient</B></P>
	1864	</TD>
	1865	<TD WIDTH=45>
	1866	<P>R (10)</P>
	1867	</TD>
	1868	<TD WIDTH=159>
	1869	<P><I>10 * 0.0</I></P>
	1870	</TD>
	1871	<TD WIDTH=1280>
	1872	<P>Gradient(s) of the leaf area density (in m<SUP>2</SUP>/m<SUP>4</SUP>).</P>
	1873	<P>This leaf area density gradient holds starting from the height
	1874	level defined by <A HREF="#lad_vertical_gradient_level">lad_vertical_gradient_level</A>
	1875	(precisely: for all uv levels k where zu(k) >
	1876	lad_vertical_gradient_level, lad(k) is set: lad(k) = lad(k-1) +
	1877	dzu(k) * <B>lad_vertical_gradient</B>) up to the level defined by
	1878	<A HREF="#pch_index">pch_index</A>. Above that level lad(k) will
	1879	automatically set to 0.0. A total of 10 different gradients for 11
	1880	height intervals (10 intervals if <A HREF="#lad_vertical_gradient_level">lad_vertical_gradient_level</A>(1)
	1881	= <I>0.0</I>) can be assigned. The leaf area density at the
	1882	surface is assigned via <A HREF="#lad_surface">lad_surface</A>.
	1883	</P>
	1884	</TD>
	1885	</TR>
	1886	<TR>
	1887	<TD WIDTH=126>
	1888	<P><A NAME="lad_vertical_gradient_level"></A><B>lad_vertical_gradient_level</B></P>
	1889	</TD>
	1890	<TD WIDTH=45>
	1891	<P>R (10)</P>
	1892	</TD>
	1893	<TD WIDTH=159>
	1894	<P><I>10 * 0.0</I></P>
	1895	</TD>
	1896	<TD WIDTH=1280>
	1897	<P>Height level from which on the gradient of the leaf area
	1898	density defined by <A HREF="#lad_vertical_gradient_level">lad_vertical_gradient_level</A>
	1899	is effective (in m).<BR><BR>The height levels have to be assigned
	1900	in ascending order. The default values result in a leaf area
	1901	density that is constant with height uup to the top of the plant
	1902	canopy layer defined by <A HREF="#pch_index">pch_index</A>. For
	1903	the piecewise construction of temperature profiles see
	1904	<A HREF="#lad_vertical_gradient">lad_vertical_gradient</A>.</P>
	1905	</TD>
	1906	</TR>
	1907	<TR>
	1908	<TD WIDTH=126>
	1909	<P><A NAME="leaf_surface_concentration"></A><B>leaf_surface_concentration</B></P>
	1910	</TD>
	1911	<TD WIDTH=45>
	1912	<P>R</P>
	1913	</TD>
	1914	<TD WIDTH=159>
	1915	<P><I>0.0</I></P>
	1916	</TD>
	1917	<TD WIDTH=1280>
	1918	<P>Concentration of a passive scalar at the surface of a leaf (in
	1919	K m/s).<BR><BR>This parameter is only of importance in cases in
	1920	that both, <A HREF="#plant_canopy">plant_canopy</A> and
	1921	<A HREF="#passive_scalar">passive_scalar</A>, are set <I>.T.</I>.
	1922	The value of the concentration of a passive scalar at the surface
	1923	of a leaf is required for the parametrisation of the sources and
	1924	sinks of scalar concentration due to the canopy.</P>
	1925	</TD>
	1926	</TR>
	1927	<TR>
	1928	<TD WIDTH=126>
	1929	<P><A NAME="long_filter_factor"></A><B>long_filter_factor</B></P>
	1930	</TD>
	1931	<TD WIDTH=45>
	1932	<P>R</P>
	1933	</TD>
	1934	<TD WIDTH=159>
	1935	<P><I>0.0</I></P>
	1936	</TD>
	1937	<TD WIDTH=1280>
	1938	<P>Filter factor for the so-called Long-filter.</P>
	1939	<P><BR>This filter very efficiently eliminates 2-delta-waves
	1940	sometimes cauesed by the upstream-spline scheme (see Mahrer and
	1941	Pielke, 1978: Mon. Wea. Rev., 106, 818-830). It works in all three
	1942	directions in space. A value of <B>long_filter_factor</B> = <I>0.01</I>
	1943	sufficiently removes the small-scale waves without affecting the
	1944	longer waves.</P>
	1945	<P>By default, the filter is switched off (= <I>0.0</I>). It is
	1946	exclusively applied to the tendencies calculated by the
	1947	upstream-spline scheme (see <A HREF="#momentum_advec">momentum_advec</A>
	1948	and <A HREF="#scalar_advec">scalar_advec</A>), not to the
	1949	prognostic variables themselves. At the bottom and top boundary of
	1950	the model domain the filter effect for vertical 2-delta-waves is
	1951	reduced. There, the amplitude of these waves is only reduced by
	1952	approx. 50%, otherwise by nearly 100%.  <BR>Filter factors
	1953	with values > <I>0.01</I> also reduce the amplitudes of waves
	1954	with wavelengths longer than 2-delta (see the paper by Mahrer and
	1955	Pielke, quoted above).
	1956	</P>
	1957	</TD>
	1958	</TR>
	1959	<TR>
	1960	<TD WIDTH=126>
	1961	<P><A NAME="loop_optimization"></A><B>loop_optimization</B></P>
	1962	</TD>
	1963	<TD WIDTH=45>
	1964	<P>C*16</P>
	1965	</TD>
	1966	<TD WIDTH=159>
	1967	<P><I>see right</I></P>
	1968	</TD>
	1969	<TD WIDTH=1280>
	1970	<P>Method used to optimize loops for solving the prognostic
	1971	equations .<BR><BR>By default, the optimization method depends on
	1972	the host on which PALM is running. On machines with vector-type
	1973	CPUs, single 3d-loops are used to calculate each tendency term of
	1974	each prognostic equation, while on all other machines, all
	1975	prognostic equations are solved within one big loop over the two
	1976	horizontal indices <FONT FACE="Courier New, Courier, monospace">i
	1977	</FONT>and <FONT FACE="Courier New, Courier, monospace">j </FONT>(giving
	1978	a good cache uitilization).<BR><BR>The default behaviour can be
	1979	changed by setting either <B>loop_optimization</B> = <I>'vector'</I>
	1980	or <B>loop_optimization</B> = <I>'cache'</I>.</P>
	1981	</TD>
	1982	</TR>
	1983	<TR>
	1984	<TD WIDTH=126>
	1985	<P><A NAME="mixing_length_1d"></A><B>mixing_length_1d</B></P>
	1986	</TD>
	1987	<TD WIDTH=45>
	1988	<P>C*20</P>
	1989	</TD>
	1990	<TD WIDTH=159>
	1991	<P><I>'as_in_3d_</I><BR><I>model'</I></P>
	1992	</TD>
	1993	<TD WIDTH=1280>
	1994	<P>Mixing length used in the 1d-model.<BR><BR>By default the
	1995	mixing length is calculated as in the 3d-model (i.e. it depends on
	1996	the grid spacing).<BR><BR>By setting <B>mixing_length_1d</B> =
	1997	<I>'blackadar'</I>, the so-called Blackadar mixing length is used
	1998	(l = kappa * z / ( 1 + kappa * z / lambda ) with the limiting
	1999	value lambda = 2.7E-4 * u_g / f).</P>
	2000	</TD>
	2001	</TR>
	2002	<TR>
	2003	<TD WIDTH=126>
	2004	<P><A NAME="momentum_advec"></A><B>momentum_advec</B></P>
	2005	</TD>
	2006	<TD WIDTH=45>
	2007	<P>C * 10</P>
	2008	</TD>
	2009	<TD WIDTH=159>
	2010	<P><I>'pw-scheme'</I></P>
	2011	</TD>
	2012	<TD WIDTH=1280>
	2013	<P>Advection scheme to be used for the momentum equations.<BR><BR>The
	2014	user can choose between the following schemes:<BR> <BR><BR><I>'pw-scheme'</I></P>
	2015	<P STYLE="margin-left: 0.42in">The scheme of Piascek and Williams
	2016	(1970, J. Comp. Phys., 6, 392-405) with central differences in the
	2017	form C3 is used.<BR>If intermediate Euler-timesteps are carried
	2018	out in case of <A HREF="#timestep_scheme">timestep_scheme</A> =
	2019	<I>'leapfrog+euler'</I> the advection scheme is - for the
	2020	Euler-timestep - automatically switched to an upstream-scheme.</P>
	2021	<P><I>'ups-scheme'</I></P>
	2022	<P STYLE="margin-left: 0.42in">The upstream-spline scheme is used
	2023	(see Mahrer and Pielke, 1978: Mon. Wea. Rev., 106, 818-830). In
	2024	opposite to the Piascek-Williams scheme, this is characterized by
	2025	much better numerical features (less numerical diffusion, better
	2026	preservation of flow structures, e.g. vortices), but
	2027	computationally it is much more expensive. In addition, the use of
	2028	the Euler-timestep scheme is mandatory (<A HREF="#timestep_scheme">timestep_scheme</A>
	2029	= <I>'euler'</I>), i.e. the timestep accuracy is only of first
	2030	order. For this reason the advection of scalar variables (see
	2031	<A HREF="#scalar_advec">scalar_advec</A>) should then also be
	2032	carried out with the upstream-spline scheme, because otherwise the
	2033	scalar variables would be subject to large numerical diffusion due
	2034	to the upstream scheme.
	2035	</P>
	2036	<P STYLE="margin-left: 0.42in">Since the cubic splines used tend
	2037	to overshoot under certain circumstances, this effect must be
	2038	adjusted by suitable filtering and smoothing (see
	2039	<A HREF="#cut_spline_overshoot">cut_spline_overshoot</A>,
	2040	<A HREF="#long_filter_factor">long_filter_factor</A>,
	2041	<A HREF="#ups_limit_pt">ups_limit_pt</A>, <A HREF="#ups_limit_u">ups_limit_u</A>,
	2042	<A HREF="#ups_limit_v">ups_limit_v</A>, <A HREF="#ups_limit_w">ups_limit_w</A>).
	2043	This is always neccessary for runs with stable stratification,
	2044	even if this stratification appears only in parts of the model
	2045	domain.</P>
	2046	<P STYLE="margin-left: 0.42in">With stable stratification the
	2047	upstream-spline scheme also produces gravity waves with large
	2048	amplitude, which must be suitably damped (see
	2049	<A HREF="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</A>).<BR><BR><B>Important:
	2050	</B>The  upstream-spline scheme is not implemented for
	2051	humidity and passive scalars (see <A HREF="#humidity">humidity</A>
	2052	and <A HREF="#passive_scalar">passive_scalar</A>) and requires the
	2053	use of a 2d-domain-decomposition. The last conditions severely
	2054	restricts code optimization on several machines leading to very
	2055	long execution times! The scheme is also not allowed for
	2056	non-cyclic lateral boundary conditions (see <A HREF="#bc_lr">bc_lr</A>
	2057	and <A HREF="#bc_ns">bc_ns</A>).</P>
	2058	</TD>
	2059	</TR>
	2060	<TR>
	2061	<TD WIDTH=126>
	2062	<P><A NAME="netcdf_precision"></A><B>netcdf_precision</B></P>
	2063	</TD>
	2064	<TD WIDTH=45>
	2065	<P>C*20<BR>(10)</P>
	2066	</TD>
	2067	<TD WIDTH=159>
	2068	<P><I>single preci-</I><BR><I>sion for all</I><BR><I>output
	2069	quan-</I><BR><I>tities</I></P>
	2070	</TD>
	2071	<TD WIDTH=1280>
	2072	<P>Defines the accuracy of the NetCDF output.<BR><BR>By default,
	2073	all NetCDF output data (see <A HREF="chapter_4.2.html#data_output_format">data_output_format</A>)
	2074	have single precision  (4 byte) accuracy. Double precision (8
	2075	byte) can be choosen alternatively.<BR>Accuracy for the different
	2076	output data (cross sections, 3d-volume data, spectra, etc.) can be
	2077	set independently.<BR><I>'<out>_NF90_REAL4'</I> (single
	2078	precision) or <I>'<out>_NF90_REAL8'</I> (double precision)
	2079	are the two principally allowed values for <B>netcdf_precision</B>,
	2080	where the string <I>'<out>' </I>can be chosen out of the
	2081	following list:</P>
	2082	<TABLE BORDER=1 CELLPADDING=2 CELLSPACING=2>
	2083	<TR>
	2084	<TD>
	2085	<P><I>'xy'</I></P>
	2086	</TD>
	2087	<TD>
	2088	<P>horizontal cross section</P>
	2089	</TD>
	2090	</TR>
	2091	<TR>
	2092	<TD>
	2093	<P><I>'xz'</I></P>
	2094	</TD>
	2095	<TD>
	2096	<P>vertical (xz) cross section</P>
	2097	</TD>
	2098	</TR>
	2099	<TR>
	2100	<TD>
	2101	<P><I>'yz'</I></P>
	2102	</TD>
	2103	<TD>
	2104	<P>vertical (yz) cross section</P>
	2105	</TD>
	2106	</TR>
	2107	<TR>
	2108	<TD>
	2109	<P><I>'2d'</I></P>
	2110	</TD>
	2111	<TD>
	2112	<P>all cross sections</P>
	2113	</TD>
	2114	</TR>
	2115	<TR>
	2116	<TD>
	2117	<P><I>'3d'</I></P>
	2118	</TD>
	2119	<TD>
	2120	<P>volume data</P>
	2121	</TD>
	2122	</TR>
	2123	<TR>
	2124	<TD>
	2125	<P><I>'pr'</I></P>
	2126	</TD>
	2127	<TD>
	2128	<P>vertical profiles</P>
	2129	</TD>
	2130	</TR>
	2131	<TR>
	2132	<TD>
	2133	<P><I>'ts'</I></P>
	2134	</TD>
	2135	<TD>
	2136	<P>time series, particle time series</P>
	2137	</TD>
	2138	</TR>
	2139	<TR>
	2140	<TD>
	2141	<P><I>'sp'</I></P>
	2142	</TD>
	2143	<TD>
	2144	<P>spectra</P>
	2145	</TD>
	2146	</TR>
	2147	<TR>
	2148	<TD>
	2149	<P><I>'prt'</I></P>
	2150	</TD>
	2151	<TD>
	2152	<P>particles</P>
	2153	</TD>
	2154	</TR>
	2155	<TR>
	2156	<TD>
	2157	<P><I>'all'</I></P>
	2158	</TD>
	2159	<TD>
	2160	<P>all output quantities</P>
	2161	</TD>
	2162	</TR>
	2163	</TABLE>
	2164	<P><BR><B>Example:</B><BR>If all cross section data and the
	2165	particle data shall be output in double precision and all other
	2166	quantities in single precision, then <B>netcdf_precision</B> =
	2167	<I>'2d_NF90_REAL8'</I>, <I>'prt_NF90_REAL8'</I> has to be
	2168	assigned.</P>
	2169	</TD>
	2170	</TR>
	2171	<TR>
	2172	<TD WIDTH=126>
	2173	<P><A NAME="nsor_ini"></A><B>nsor_ini</B></P>
	2174	</TD>
	2175	<TD WIDTH=45>
	2176	<P>I</P>
	2177	</TD>
	2178	<TD WIDTH=159>
	2179	<P><I>100</I></P>
	2180	</TD>
	2181	<TD WIDTH=1280>
	2182	<P>Initial number of iterations with the SOR algorithm.
	2183	</P>
	2184	<P>This parameter is only effective if the SOR algorithm was
	2185	selected as the pressure solver scheme (<A HREF="chapter_4.2.html#psolver">psolver</A>
	2186	= <I>'sor'</I>) and specifies the number of initial iterations of
	2187	the SOR scheme (at t = 0). The number of subsequent iterations at
	2188	the following timesteps is determined with the parameter <A HREF="#nsor">nsor</A>.
	2189	Usually <B>nsor</B> < <B>nsor_ini</B>, since in each case
	2190	subsequent calls to <A HREF="chapter_4.2.html#psolver">psolver</A>
	2191	use the solution of the previous call as initial value. Suitable
	2192	test runs should determine whether sufficient convergence of the
	2193	solution is obtained with the default value and if necessary the
	2194	value of <B>nsor_ini</B> should be changed.</P>
	2195	</TD>
	2196	</TR>
	2197	<TR>
	2198	<TD WIDTH=126>
	2199	<P><A NAME="nx"></A><B>nx</B></P>
	2200	</TD>
	2201	<TD WIDTH=45>
	2202	<P>I</P>
	2203	</TD>
	2204	<TD WIDTH=159>
	2205	<P><BR><BR>
	2206	</P>
	2207	</TD>
	2208	<TD WIDTH=1280>
	2209	<P>Number of grid points in x-direction.
	2210	</P>
	2211	<P>A value for this parameter must be assigned. Since the lower
	2212	array bound in PALM starts with i = 0, the actual number of grid
	2213	points is equal to <B>nx+1</B>. In case of cyclic boundary
	2214	conditions along x, the domain size is (<B>nx+1</B>)* <A HREF="#dx">dx</A>.</P>
	2215	<P>For parallel runs, in case of <A HREF="#grid_matching">grid_matching</A>
	2216	= <I>'strict'</I>, <B>nx+1</B> must be an integral multiple of the
	2217	processor numbers (see <A HREF="#npex">npex</A> and <A HREF="#npey">npey</A>)
	2218	along x- as well as along y-direction (due to data transposition
	2219	restrictions).</P>
	2220	<P>For <A HREF="chapter_3.8.html">coupled runs</A> this parameter
	2221	must be equal in both parameter files <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN</FONT></A>
	2222	and <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN_O</FONT></A>.</P>
	2223	</TD>
	2224	</TR>
	2225	<TR>
	2226	<TD WIDTH=126>
	2227	<P><A NAME="ny"></A><B>ny</B></P>
	2228	</TD>
	2229	<TD WIDTH=45>
	2230	<P>I</P>
	2231	</TD>
	2232	<TD WIDTH=159>
	2233	<P><BR><BR>
	2234	</P>
	2235	</TD>
	2236	<TD WIDTH=1280>
	2237	<P>Number of grid points in y-direction.
	2238	</P>
	2239	<P>A value for this parameter must be assigned. Since the lower
	2240	array bound in PALM starts with j = 0, the actual number of grid
	2241	points is equal to <B>ny+1</B>. In case of cyclic boundary
	2242	conditions along y, the domain size is (<B>ny+1</B>) * <A HREF="#dy">dy</A>.</P>
	2243	<P>For parallel runs, in case of <A HREF="#grid_matching">grid_matching</A>
	2244	= <I>'strict'</I>, <B>ny+1</B> must be an integral multiple of the
	2245	processor numbers (see <A HREF="#npex">npex</A> and <A HREF="#npey">npey</A>)
	2246	along y- as well as along x-direction (due to data transposition
	2247	restrictions).</P>
	2248	<P>For <A HREF="chapter_3.8.html">coupled runs</A> this parameter
	2249	must be equal in both parameter files <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN</FONT></A>
	2250	and <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN_O</FONT></A>.</P>
	2251	</TD>
	2252	</TR>
	2253	<TR>
	2254	<TD WIDTH=126>
	2255	<P><A NAME="nz"></A><B>nz</B></P>
	2256	</TD>
	2257	<TD WIDTH=45>
	2258	<P>I</P>
	2259	</TD>
	2260	<TD WIDTH=159>
	2261	<P><BR><BR>
	2262	</P>
	2263	</TD>
	2264	<TD WIDTH=1280>
	2265	<P>Number of grid points in z-direction.
	2266	</P>
	2267	<P>A value for this parameter must be assigned. Since the lower
	2268	array bound in PALM starts with k = 0 and since one additional
	2269	grid point is added at the top boundary (k = <B>nz+1</B>), the
	2270	actual number of grid points is <B>nz+2</B>. However, the
	2271	prognostic equations are only solved up to <B>nz</B> (u, v) or up
	2272	to <B>nz-1</B> (w, scalar quantities). The top boundary for u and
	2273	v is at k = <B>nz+1</B> (u, v) while at k = <B>nz</B> for all
	2274	other quantities.
	2275	</P>
	2276	<P>For parallel runs,  in case of <A HREF="#grid_matching">grid_matching</A>
	2277	= <I>'strict'</I>, <B>nz</B> must be an integral multiple of the
	2278	number of processors in x-direction (due to data transposition
	2279	restrictions).</P>
	2280	</TD>
	2281	</TR>
	2282	<TR>
	2283	<TD WIDTH=126>
	2284	<P><A NAME="ocean"></A><B>ocean</B></P>
	2285	</TD>
	2286	<TD WIDTH=45>
	2287	<P>L</P>
	2288	</TD>
	2289	<TD WIDTH=159>
	2290	<P><I>.F.</I></P>
	2291	</TD>
	2292	<TD WIDTH=1280>
	2293	<P>Parameter to switch on ocean runs.<BR><BR>By default PALM
	2294	is configured to simulate atmospheric flows. However,
	2295	starting from version 3.3, <B>ocean</B> = <I>.T.</I>
	2296	allows simulation of ocean turbulent flows. Setting this
	2297	switch has several effects:</P>
	2298	<UL>
	2299	<LI><P STYLE="margin-bottom: 0in">An additional prognostic
	2300	equation for salinity is solved.
	2301	</P>
	2302	<LI><P STYLE="margin-bottom: 0in">Potential temperature in
	2303	buoyancy and stability-related terms is replaced by potential
	2304	density.
	2305	</P>
	2306	<LI><P STYLE="margin-bottom: 0in">Potential density is calculated
	2307	from the equation of state for seawater after each timestep,
	2308	using the algorithm proposed by Jackett et al. (2006, J. Atmos.
	2309	Oceanic Technol., <B>23</B>, 1709-1728).<BR>So far, only the
	2310	initial hydrostatic pressure is entered into this equation.
	2311	</P>
	2312	<LI><P STYLE="margin-bottom: 0in">z=0 (sea surface) is assumed at
	2313	the model top (vertical grid index <FONT FACE="Courier New, Courier, monospace">k=nzt</FONT>
	2314	on the w-grid), with negative values of z indicating the depth.
	2315	</P>
	2316	<LI><P STYLE="margin-bottom: 0in">Initial profiles are
	2317	constructed (e.g. from <A HREF="#pt_vertical_gradient">pt_vertical_gradient</A>
	2318	/ <A HREF="#pt_vertical_gradient_level">pt_vertical_gradient_level</A>)
	2319	starting from the sea surface, using surface values given by
	2320	<A HREF="#pt_surface">pt_surface</A>, <A HREF="#sa_surface">sa_surface</A>,
	2321	<A HREF="#ug_surface">ug_surface</A>, and <A HREF="#vg_surface">vg_surface</A>.
	2322	</P>
	2323	<LI><P STYLE="margin-bottom: 0in">Zero salinity flux is used as
	2324	default boundary condition at the bottom of the sea.
	2325	</P>
	2326	<LI><P>If switched on, random perturbations are by default
	2327	imposed to the upper model domain from zu(nzt*2/3) to zu(nzt-3).
	2328	</P>
	2329	</UL>
	2330	<P><BR>Relevant parameters to be exclusively used for steering
	2331	ocean runs are <A HREF="#bc_sa_t">bc_sa_t</A>,
	2332	<A HREF="#bottom_salinityflux">bottom_salinityflux</A>,
	2333	<A HREF="#sa_surface">sa_surface</A>, <A HREF="#sa_vertical_gradient">sa_vertical_gradient</A>,
	2334	<A HREF="#sa_vertical_gradient_level">sa_vertical_gradient_level</A>,
	2335	and <A HREF="#top_salinityflux">top_salinityflux</A>.<BR><BR>Section
	2336	<A HREF="chapter_4.2.2.html">4.4.2</A> gives an example for
	2337	appropriate settings of these and other parameters neccessary for
	2338	ocean runs.<BR><BR><B>ocean</B> = <I>.T.</I> does not allow
	2339	settings of <A HREF="#timestep_scheme">timestep_scheme</A> =
	2340	<I>'leapfrog'</I> or <I>'leapfrog+euler'</I> as well as
	2341	<A HREF="#scalar_advec">scalar_advec</A> = <I>'ups-scheme'</I>.</P>
	2342	</TD>
	2343	</TR>
	2344	<TR>
	2345	<TD WIDTH=126>
	2346	<P><A NAME="omega"></A><B>omega</B></P>
	2347	</TD>
	2348	<TD WIDTH=45>
	2349	<P>R</P>
	2350	</TD>
	2351	<TD WIDTH=159>
	2352	<P><I>7.29212E-5</I></P>
	2353	</TD>
	2354	<TD WIDTH=1280>
	2355	<P>Angular velocity of the rotating system (in rad s<SUP>-1</SUP>).
	2356	</P>
	2357	<P>The angular velocity of the earth is set by default. The values
	2358	of the Coriolis parameters are calculated as:
	2359	</P>
	2360	<UL>
	2361	<P>f = 2.0 * <B>omega</B> * sin(<A HREF="#phi">phi</A>)  <BR>f*
	2362	= 2.0 * <B>omega</B> * cos(<A HREF="#phi">phi</A>)</P>
	2363	</UL>
	2364	</TD>
	2365	</TR>
	2366	<TR>
	2367	<TD WIDTH=126>
	2368	<P><A NAME="outflow_damping_width"></A><B>outflow_damping_width</B></P>
	2369	</TD>
	2370	<TD WIDTH=45>
	2371	<P>I</P>
	2372	</TD>
	2373	<TD WIDTH=159>
	2374	<P><I>MIN(20, nx/2</I> or <I>ny/2)</I></P>
	2375	</TD>
	2376	<TD WIDTH=1280>
	2377	<P>Width of the damping range in the vicinity of the outflow
	2378	(gridpoints).<BR><BR>When using non-cyclic lateral boundaries (see
	2379	<A HREF="#bc_lr">bc_lr</A> or <A HREF="#bc_ns">bc_ns</A>), a
	2380	smoothing has to be applied to the velocity field in the vicinity
	2381	of the outflow in order to suppress any reflections of outgoing
	2382	disturbances. This parameter controlls the horizontal range to
	2383	which the smoothing is applied. The range is given in gridpoints
	2384	counted from the respective outflow boundary. For further details
	2385	about the smoothing see parameter <A HREF="#km_damp_max">km_damp_max</A>,
	2386	which defines the magnitude of the damping.</P>
	2387	</TD>
	2388	</TR>
	2389	<TR>
	2390	<TD WIDTH=126>
	2391	<P><A NAME="overshoot_limit_e"></A><B>overshoot_limit_e</B></P>
	2392	</TD>
	2393	<TD WIDTH=45>
	2394	<P>R</P>
	2395	</TD>
	2396	<TD WIDTH=159>
	2397	<P><I>0.0</I></P>
	2398	</TD>
	2399	<TD WIDTH=1280>
	2400	<P>Allowed limit for the overshooting of subgrid-scale TKE in case
	2401	that the upstream-spline scheme is switched on (in m<SUP>2</SUP>/s<SUP>2</SUP>).
	2402	</P>
	2403	<P>By deafult, if cut-off of overshoots is switched on for the
	2404	upstream-spline scheme (see <A HREF="#cut_spline_overshoot">cut_spline_overshoot</A>),
	2405	no overshoots are permitted at all. If <B>overshoot_limit_e</B> is
	2406	given a non-zero value, overshoots with the respective amplitude
	2407	(both upward and downward) are allowed.
	2408	</P>
	2409	<P>Only positive values are allowed for <B>overshoot_limit_e</B>.</P>
	2410	</TD>
	2411	</TR>
	2412	<TR>
	2413	<TD WIDTH=126>
	2414	<P><A NAME="overshoot_limit_pt"></A><B>overshoot_limit_pt</B></P>
	2415	</TD>
	2416	<TD WIDTH=45>
	2417	<P>R</P>
	2418	</TD>
	2419	<TD WIDTH=159>
	2420	<P><I>0.0</I></P>
	2421	</TD>
	2422	<TD WIDTH=1280>
	2423	<P>Allowed limit for the overshooting of potential temperature in
	2424	case that the upstream-spline scheme is switched on (in K).
	2425	</P>
	2426	<P>For further information see <A HREF="#overshoot_limit_e">overshoot_limit_e</A>.
	2427	</P>
	2428	<P>Only positive values are allowed for <B>overshoot_limit_pt</B>.</P>
	2429	</TD>
	2430	</TR>
	2431	<TR>
	2432	<TD WIDTH=126>
	2433	<P><A NAME="overshoot_limit_u"></A><B>overshoot_limit_u</B></P>
	2434	</TD>
	2435	<TD WIDTH=45>
	2436	<P>R</P>
	2437	</TD>
	2438	<TD WIDTH=159>
	2439	<P><I>0.0</I></P>
	2440	</TD>
	2441	<TD WIDTH=1280>
	2442	<P>Allowed limit for the overshooting of the u-component of
	2443	velocity in case that the upstream-spline scheme is switched on
	2444	(in m/s).
	2445	</P>
	2446	<P>For further information see <A HREF="#overshoot_limit_e">overshoot_limit_e</A>.
	2447	</P>
	2448	<P>Only positive values are allowed for <B>overshoot_limit_u</B>.</P>
	2449	</TD>
	2450	</TR>
	2451	<TR>
	2452	<TD WIDTH=126>
	2453	<P><A NAME="overshoot_limit_v"></A><B>overshoot_limit_v</B></P>
	2454	</TD>
	2455	<TD WIDTH=45>
	2456	<P>R</P>
	2457	</TD>
	2458	<TD WIDTH=159>
	2459	<P><I>0.0</I></P>
	2460	</TD>
	2461	<TD WIDTH=1280>
	2462	<P>Allowed limit for the overshooting of the v-component of
	2463	velocity in case that the upstream-spline scheme is switched on
	2464	(in m/s).
	2465	</P>
	2466	<P>For further information see <A HREF="#overshoot_limit_e">overshoot_limit_e</A>.
	2467	</P>
	2468	<P>Only positive values are allowed for <B>overshoot_limit_v</B>.</P>
	2469	</TD>
	2470	</TR>
	2471	<TR>
	2472	<TD WIDTH=126>
	2473	<P><A NAME="overshoot_limit_w"></A><B>overshoot_limit_w</B></P>
	2474	</TD>
	2475	<TD WIDTH=45>
	2476	<P>R</P>
	2477	</TD>
	2478	<TD WIDTH=159>
	2479	<P><I>0.0</I></P>
	2480	</TD>
	2481	<TD WIDTH=1280>
	2482	<P>Allowed limit for the overshooting of the w-component of
	2483	velocity in case that the upstream-spline scheme is switched on
	2484	(in m/s).
	2485	</P>
	2486	<P>For further information see <A HREF="#overshoot_limit_e">overshoot_limit_e</A>.
	2487	</P>
	2488	<P>Only positive values are permitted for <B>overshoot_limit_w</B>.</P>
	2489	</TD>
	2490	</TR>
	2491	<TR>
	2492	<TD WIDTH=126>
	2493	<P><A NAME="passive_scalar"></A><B>passive_scalar</B></P>
	2494	</TD>
	2495	<TD WIDTH=45>
	2496	<P>L</P>
	2497	</TD>
	2498	<TD WIDTH=159>
	2499	<P><I>.F.</I></P>
	2500	</TD>
	2501	<TD WIDTH=1280>
	2502	<P>Parameter to switch on the prognostic equation for a passive
	2503	scalar.
	2504	</P>
	2505	<P>The initial vertical profile of s can be set via parameters
	2506	<A HREF="#s_surface">s_surface</A>, <A HREF="#s_vertical_gradient">s_vertical_gradient</A>
	2507	and  <A HREF="#s_vertical_gradient_level">s_vertical_gradient_level</A>.
	2508	Boundary conditions can be set via <A HREF="#s_surface_initial_change">s_surface_initial_change</A>
	2509	and <A HREF="#surface_scalarflux">surface_scalarflux</A>.
	2510	</P>
	2511	<P><B>Note:</B> <BR>With <B>passive_scalar</B> switched on, the
	2512	simultaneous use of humidity (see <A HREF="#humidity">humidity</A>)
	2513	is impossible.</P>
	2514	</TD>
	2515	</TR>
	2516	<TR>
	2517	<TD WIDTH=126>
	2518	<P><A NAME="pch_index"></A><B>pch_index</B></P>
	2519	</TD>
	2520	<TD WIDTH=45>
	2521	<P>I</P>
	2522	</TD>
	2523	<TD WIDTH=159>
	2524	<P><I>0</I></P>
	2525	</TD>
	2526	<TD WIDTH=1280>
	2527	<P>Grid point index (scalar) of the upper boundary of the plant
	2528	canopy layer.<BR><BR>Above <B>pch_index</B> the arrays of leaf
	2529	area density and drag_coeffient are automatically set to zero in
	2530	case of <A HREF="#plant_canopy">plant_canopy</A> = .T.. Up to
	2531	<B>pch_index</B> a leaf area density profile can be prescribed by
	2532	using the parameters <A HREF="#lad_surface">lad_surface</A>,
	2533	<A HREF="#lad_vertical_gradient">lad_vertical_gradient</A> and
	2534	<A HREF="#lad_vertical_gradient_level">lad_vertical_gradient_level</A>.</P>
	2535	</TD>
	2536	</TR>
	2537	<TR>
	2538	<TD WIDTH=126>
	2539	<P><A NAME="phi"></A><B>phi</B></P>
	2540	</TD>
	2541	<TD WIDTH=45>
	2542	<P>R</P>
	2543	</TD>
	2544	<TD WIDTH=159>
	2545	<P><I>55.0</I></P>
	2546	</TD>
	2547	<TD WIDTH=1280>
	2548	<P>Geographical latitude (in degrees).
	2549	</P>
	2550	<P>The value of this parameter determines the value of the
	2551	Coriolis parameters f and f*, provided that the angular velocity
	2552	(see <A HREF="#omega">omega</A>) is non-zero.</P>
	2553	</TD>
	2554	</TR>
	2555	<TR>
	2556	<TD WIDTH=126>
	2557	<P><A NAME="plant_canopy"></A><B>plant_canopy</B></P>
	2558	</TD>
	2559	<TD WIDTH=45>
	2560	<P>L</P>
	2561	</TD>
	2562	<TD WIDTH=159>
	2563	<P><I>.F.</I></P>
	2564	</TD>
	2565	<TD WIDTH=1280>
	2566	<P>Switch for the plant_canopy_model.<BR><BR>If <B>plant_canopy</B>
	2567	is set <I>.T.</I>, the plant canopy model of Watanabe (2004, BLM
	2568	112, 307-341) is used. <BR>The impact of a plant canopy on a
	2569	turbulent flow is considered by an additional drag term in the
	2570	momentum equations and an additional sink term in the prognostic
	2571	equation for the subgrid-scale TKE. These additional terms are
	2572	dependent on the leaf drag coefficient (see <A HREF="#drag_coefficient">drag_coefficient</A>)
	2573	and the leaf area density (see <A HREF="#lad_surface">lad_surface</A>,
	2574	<A HREF="#lad_vertical_gradient">lad_vertical_gradient</A>,
	2575	<A HREF="#lad_vertical_gradient_level">lad_vertical_gradient_level</A>).
	2576	The top boundary of the plant canopy is determined by the
	2577	parameter <A HREF="#pch_index">pch_index</A>. For all heights
	2578	equal to or larger than zw(k=<B>pch_index</B>) the leaf area
	2579	density is 0 (i.e. there is no canopy at these heights!). <BR>By
	2580	default, a horizontally homogeneous plant canopy is prescribed,
	2581	if  <B>plant_canopy</B> is set <I>.T.</I>. However, the user
	2582	can define other types of plant canopies (see <A HREF="#canopy_mode">canopy_mode</A>).<BR><BR>If
	2583	<B>plant_canopy</B> and  <B>passive_scalar</B> are set <I>.T.</I>,
	2584	the canopy acts as an additional source or sink, respectively, of
	2585	scalar concentration. The source/sink strength is dependent on the
	2586	scalar concentration at the leaf surface, which is generally
	2587	constant with time in PALM and which can be specified by
	2588	specifying the parameter <A HREF="#leaf_surface_concentration">leaf_surface_concentration</A>.
	2589	<BR><BR>Additional heating of the air by the plant canopy is taken
	2590	into account, when the default value of the parameter <A HREF="#cthf">cthf</A>
	2591	is altered in the parameter file. In that case the value of
	2592	<A HREF="#surface_heatflux">surface_heatflux</A> specified in the
	2593	parameter file is not used in the model. Instead the near-surface
	2594	heat flux is derived from an expontial function that is dependent
	2595	on the cumulative leaf area index. <BR><BR><B>plant_canopy</B> =
	2596	<I>.T. </I>is only allowed together with a non-zero
	2597	<A HREF="#drag_coefficient">drag_coefficient</A>.</P>
	2598	</TD>
	2599	</TR>
	2600	<TR>
	2601	<TD WIDTH=126>
	2602	<P><A NAME="prandtl_layer"></A><B>prandtl_layer</B></P>
	2603	</TD>
	2604	<TD WIDTH=45>
	2605	<P>L</P>
	2606	</TD>
	2607	<TD WIDTH=159>
	2608	<P><I>.T.</I></P>
	2609	</TD>
	2610	<TD WIDTH=1280>
	2611	<P>Parameter to switch on a Prandtl layer.
	2612	</P>
	2613	<P>By default, a Prandtl layer is switched on at the bottom
	2614	boundary between z = 0 and z = 0.5 * <A HREF="#dz">dz</A> (the
	2615	first computational grid point above ground for u, v and the
	2616	scalar quantities). In this case, at the bottom boundary,
	2617	free-slip conditions for u and v (see <A HREF="#bc_uv_b">bc_uv_b</A>)
	2618	are not allowed. Likewise, laminar simulations with constant eddy
	2619	diffusivities (<A HREF="#km_constant">km_constant</A>) are
	2620	forbidden.
	2621	</P>
	2622	<P>With Prandtl-layer switched off, the TKE boundary condition
	2623	<A HREF="#bc_e_b">bc_e_b</A> = '<I>(u)*2+neumann'</I> must not
	2624	be used and is automatically changed to <I>'neumann'</I> if
	2625	necessary.  Also, the pressure boundary condition <A HREF="#bc_p_b">bc_p_b</A>
	2626	= <I>'neumann+inhomo'</I>  is not allowed.
	2627	</P>
	2628	<P>The roughness length is declared via the parameter
	2629	<A HREF="#roughness_length">roughness_length</A>.</P>
	2630	</TD>
	2631	</TR>
	2632	<TR>
	2633	<TD WIDTH=126>
	2634	<P><A NAME="precipitation"></A><B>precipitation</B></P>
	2635	</TD>
	2636	<TD WIDTH=45>
	2637	<P>L</P>
	2638	</TD>
	2639	<TD WIDTH=159>
	2640	<P><I>.F.</I></P>
	2641	</TD>
	2642	<TD WIDTH=1280>
	2643	<P>Parameter to switch on the precipitation scheme.</P>
	2644	<P>For precipitation processes PALM uses a simplified Kessler
	2645	scheme. This scheme only considers the so-called autoconversion,
	2646	that means the generation of rain water by coagulation of cloud
	2647	drops among themselves. Precipitation begins and is immediately
	2648	removed from the flow as soon as the liquid water content exceeds
	2649	the critical value of 0.5 g/kg.</P>
	2650	<P>The precipitation rate and amount can be output by assigning
	2651	the runtime parameter <A HREF="chapter_4.2.html#data_output">data_output</A>
	2652	= <I>'prr'</I> or <I>'pra'</I>, respectively. The time interval
	2653	on which the precipitation amount is defined can be controlled via
	2654	runtime parameter <A HREF="chapter_4.2.html#precipitation_amount_interval">precipitation_amount_interval</A>.</P>
	2655	</TD>
	2656	</TR>
	2657	<TR>
	2658	<TD WIDTH=126>
	2659	<P><A NAME="pt_reference"></A><B>pt_reference</B></P>
	2660	</TD>
	2661	<TD WIDTH=45>
	2662	<P>R</P>
	2663	</TD>
	2664	<TD WIDTH=159>
	2665	<P><I>use horizontal average as refrence</I></P>
	2666	</TD>
	2667	<TD WIDTH=1280>
	2668	<P>Reference temperature to be used in all buoyancy terms (in
	2669	K).<BR><BR>By default, the instantaneous horizontal average over
	2670	the total model domain is used.<BR><BR><B>Attention:</B><BR>In
	2671	case of ocean runs (see <A HREF="#ocean">ocean</A>), always a
	2672	reference temperature is used in the buoyancy terms with a default
	2673	value of <B>pt_reference</B> = <A HREF="#pt_surface">pt_surface</A>.</P>
	2674	</TD>
	2675	</TR>
	2676	<TR>
	2677	<TD WIDTH=126>
	2678	<P><A NAME="pt_surface"></A><B>pt_surface</B></P>
	2679	</TD>
	2680	<TD WIDTH=45>
	2681	<P>R</P>
	2682	</TD>
	2683	<TD WIDTH=159>
	2684	<P><I>300.0</I></P>
	2685	</TD>
	2686	<TD WIDTH=1280>
	2687	<P>Surface potential temperature (in K).
	2688	</P>
	2689	<P>This parameter assigns the value of the potential temperature
	2690	<B>pt</B> at the surface (k=0)<B>.</B> Starting from this value,
	2691	the initial vertical temperature profile is constructed with
	2692	<A HREF="#pt_vertical_gradient">pt_vertical_gradient</A> and
	2693	<A HREF="#pt_vertical_gradient_level">pt_vertical_gradient_level </A>.
	2694	This profile is also used for the 1d-model as a stationary
	2695	profile.</P>
	2696	<P><B>Attention:</B><BR>In case of ocean runs (see <A HREF="#ocean">ocean</A>),
	2697	this parameter gives the temperature value at the sea surface,
	2698	which is at k=nzt. The profile is then constructed from the
	2699	surface down to the bottom of the model.</P>
	2700	</TD>
	2701	</TR>
	2702	<TR>
	2703	<TD WIDTH=126>
	2704	<P><A NAME="pt_surface_initial_change"></A><B>pt_surface_initial</B>
	2705	<BR><B>_change</B></P>
	2706	</TD>
	2707	<TD WIDTH=45>
	2708	<P>R</P>
	2709	</TD>
	2710	<TD WIDTH=159>
	2711	<P><I>0.0</I></P>
	2712	</TD>
	2713	<TD WIDTH=1280>
	2714	<P>Change in surface temperature to be made at the beginning of
	2715	the 3d run (in K).
	2716	</P>
	2717	<P>If <B>pt_surface_initial_change</B> is set to a non-zero value,
	2718	the near surface sensible heat flux is not allowed to be given
	2719	simultaneously (see <A HREF="#surface_heatflux">surface_heatflux</A>).</P>
	2720	</TD>
	2721	</TR>
	2722	<TR>
	2723	<TD WIDTH=126>
	2724	<P><A NAME="pt_vertical_gradient"></A><B>pt_vertical_gradient</B></P>
	2725	</TD>
	2726	<TD WIDTH=45>
	2727	<P>R (10)</P>
	2728	</TD>
	2729	<TD WIDTH=159>
	2730	<P><I>10 * 0.0</I></P>
	2731	</TD>
	2732	<TD WIDTH=1280>
	2733	<P>Temperature gradient(s) of the initial temperature profile (in
	2734	K / 100 m).
	2735	</P>
	2736	<P>This temperature gradient holds starting from the height
	2737	level defined by <A HREF="#pt_vertical_gradient_level">pt_vertical_gradient_level</A>
	2738	(precisely: for all uv levels k where zu(k) >
	2739	pt_vertical_gradient_level, pt_init(k) is set: pt_init(k) =
	2740	pt_init(k-1) + dzu(k) * <B>pt_vertical_gradient</B>) up to the top
	2741	boundary or up to the next height level defined by
	2742	<A HREF="#pt_vertical_gradient_level">pt_vertical_gradient_level</A>.
	2743	A total of 10 different gradients for 11 height intervals (10
	2744	intervals if <A HREF="#pt_vertical_gradient_level">pt_vertical_gradient_level</A>(1)
	2745	= <I>0.0</I>) can be assigned. The surface temperature is assigned
	2746	via <A HREF="#pt_surface">pt_surface</A>.
	2747	</P>
	2748	<P>Example:
	2749	</P>
	2750	<UL>
	2751	<P><B>pt_vertical_gradient</B> = <I>1.0</I>, <I>0.5</I>,
	2752	<BR><B>pt_vertical_gradient_level</B> = <I>500.0</I>, <I>1000.0</I>,</P>
	2753	</UL>
	2754	<P>That defines the temperature profile to be neutrally stratified
	2755	up to z = 500.0 m with a temperature given by <A HREF="#pt_surface">pt_surface</A>.
	2756	For 500.0 m < z <= 1000.0 m the temperature gradient is 1.0
	2757	K / 100 m and for z > 1000.0 m up to the top boundary it is 0.5
	2758	K / 100 m (it is assumed that the assigned height levels
	2759	correspond with uv levels).</P>
	2760	<P><B>Attention:</B><BR>In case of ocean runs (see <A HREF="#ocean">ocean</A>),
	2761	the profile is constructed like described above, but starting from
	2762	the sea surface (k=nzt) down to the bottom boundary of the model.
	2763	Height levels have then to be given as negative values, e.g.
	2764	<B>pt_vertical_gradient_level</B> = <I>-500.0</I>, <I>-1000.0</I>.</P>
	2765	</TD>
	2766	</TR>
	2767	<TR>
	2768	<TD WIDTH=126>
	2769	<P><A NAME="pt_vertical_gradient_level"></A><B>pt_vertical_gradient</B>
	2770	<BR><B>_level</B></P>
	2771	</TD>
	2772	<TD WIDTH=45>
	2773	<P>R (10)</P>
	2774	</TD>
	2775	<TD WIDTH=159>
	2776	<P><I>10 *</I>  <I>0.0</I></P>
	2777	</TD>
	2778	<TD WIDTH=1280>
	2779	<P>Height level from which on the temperature gradient defined by
	2780	<A HREF="#pt_vertical_gradient">pt_vertical_gradient</A> is
	2781	effective (in m).
	2782	</P>
	2783	<P>The height levels have to be assigned in ascending order. The
	2784	default values result in a neutral stratification regardless of
	2785	the values of <A HREF="#pt_vertical_gradient">pt_vertical_gradient</A>
	2786	(unless the top boundary of the model is higher than 100000.0 m).
	2787	For the piecewise construction of temperature profiles see
	2788	<A HREF="#pt_vertical_gradient">pt_vertical_gradient</A>.</P>
	2789	<P><B>Attention:</B><BR>In case of ocean runs (see <A HREF="#ocean">ocean</A>),
	2790	the (negative) height levels have to be assigned in descending
	2791	order.
	2792	</P>
	2793	</TD>
	2794	</TR>
	2795	<TR>
	2796	<TD WIDTH=126>
	2797	<P><A NAME="q_surface"></A><B>q_surface</B></P>
	2798	</TD>
	2799	<TD WIDTH=45>
	2800	<P>R</P>
	2801	</TD>
	2802	<TD WIDTH=159>
	2803	<P><I>0.0</I></P>
	2804	</TD>
	2805	<TD WIDTH=1280>
	2806	<P>Surface specific humidity / total water content (kg/kg).
	2807	</P>
	2808	<P>This parameter assigns the value of the specific humidity q at
	2809	the surface (k=0).  Starting from this value, the initial
	2810	humidity profile is constructed with  <A HREF="#q_vertical_gradient">q_vertical_gradient</A>
	2811	and <A HREF="#q_vertical_gradient_level">q_vertical_gradient_level</A>.
	2812	This profile is also used for the 1d-model as a stationary
	2813	profile.</P>
	2814	</TD>
	2815	</TR>
	2816	<TR>
	2817	<TD WIDTH=126>
	2818	<P><A NAME="q_surface_initial_change"></A><B>q_surface_initial</B>
	2819	<BR><B>_change</B></P>
	2820	</TD>
	2821	<TD WIDTH=45>
	2822	<P>R</P>
	2823	</TD>
	2824	<TD WIDTH=159>
	2825	<P><I>0.0</I></P>
	2826	</TD>
	2827	<TD WIDTH=1280>
	2828	<P>Change in surface specific humidity / total water content to be
	2829	made at the beginning of the 3d run (kg/kg).
	2830	</P>
	2831	<P>If <B>q_surface_initial_change</B> is set to a non-zero value
	2832	the near surface latent heat flux (water flux) is not allowed to
	2833	be given simultaneously (see <A HREF="#surface_waterflux">surface_waterflux</A>).</P>
	2834	</TD>
	2835	</TR>
	2836	<TR>
	2837	<TD WIDTH=126>
	2838	<P><A NAME="q_vertical_gradient"></A><B>q_vertical_gradient</B></P>
	2839	</TD>
	2840	<TD WIDTH=45>
	2841	<P>R (10)</P>
	2842	</TD>
	2843	<TD WIDTH=159>
	2844	<P><I>10 * 0.0</I></P>
	2845	</TD>
	2846	<TD WIDTH=1280>
	2847	<P>Humidity gradient(s) of the initial humidity profile (in 1/100
	2848	m).
	2849	</P>
	2850	<P>This humidity gradient holds starting from the height level
	2851	defined by <A HREF="#q_vertical_gradient_level">q_vertical_gradient_level</A>
	2852	(precisely: for all uv levels k, where zu(k) >
	2853	q_vertical_gradient_level, q_init(k) is set: q_init(k) =
	2854	q_init(k-1) + dzu(k) * <B>q_vertical_gradient</B>) up to the top
	2855	boundary or up to the next height level defined by
	2856	<A HREF="#q_vertical_gradient_level">q_vertical_gradient_level</A>.
	2857	A total of 10 different gradients for 11 height intervals (10
	2858	intervals if <A HREF="#q_vertical_gradient_level">q_vertical_gradient_level</A>(1)
	2859	= <I>0.0</I>) can be asigned. The surface humidity is assigned via
	2860	<A HREF="#q_surface">q_surface</A>.
	2861	</P>
	2862	<P>Example:
	2863	</P>
	2864	<UL>
	2865	<P><B>q_vertical_gradient</B> = <I>0.001</I>, <I>0.0005</I>,
	2866	<BR><B>q_vertical_gradient_level</B> = <I>500.0</I>, <I>1000.0</I>,</P>
	2867	</UL>
	2868	<P>That defines the humidity to be constant with height up to z =
	2869	500.0 m with a value given by <A HREF="#q_surface">q_surface</A>.
	2870	For 500.0 m < z <= 1000.0 m the humidity gradient is 0.001 /
	2871	100 m and for z > 1000.0 m up to the top boundary it is 0.0005
	2872	/ 100 m (it is assumed that the assigned height levels correspond
	2873	with uv levels).
	2874	</P>
	2875	</TD>
	2876	</TR>
	2877	<TR>
	2878	<TD WIDTH=126>
	2879	<P><A NAME="q_vertical_gradient_level"></A><B>q_vertical_gradient</B>
	2880	<BR><B>_level</B></P>
	2881	</TD>
	2882	<TD WIDTH=45>
	2883	<P>R (10)</P>
	2884	</TD>
	2885	<TD WIDTH=159>
	2886	<P><I>10 *</I>  <I>0.0</I></P>
	2887	</TD>
	2888	<TD WIDTH=1280>
	2889	<P>Height level from which on the humidity gradient defined by
	2890	<A HREF="#q_vertical_gradient">q_vertical_gradient</A> is
	2891	effective (in m).
	2892	</P>
	2893	<P>The height levels are to be assigned in ascending order. The
	2894	default values result in a humidity constant with height
	2895	regardless of the values of <A HREF="#q_vertical_gradient">q_vertical_gradient</A>
	2896	(unless the top boundary of the model is higher than 100000.0 m).
	2897	For the piecewise construction of humidity profiles see
	2898	<A HREF="#q_vertical_gradient">q_vertical_gradient</A>.</P>
	2899	</TD>
	2900	</TR>
	2901	<TR>
	2902	<TD WIDTH=126>
	2903	<P><A NAME="radiation"></A><B>radiation</B></P>
	2904	</TD>
	2905	<TD WIDTH=45>
	2906	<P>L</P>
	2907	</TD>
	2908	<TD WIDTH=159>
	2909	<P><I>.F.</I></P>
	2910	</TD>
	2911	<TD WIDTH=1280>
	2912	<P>Parameter to switch on longwave radiation cooling at
	2913	cloud-tops.
	2914	</P>
	2915	<P>Long-wave radiation processes are parameterized by the
	2916	effective emissivity, which considers only the absorption and
	2917	emission of long-wave radiation at cloud droplets. The radiation
	2918	scheme can be used only with <A HREF="#cloud_physics">cloud_physics</A>
	2919	= .TRUE. .</P>
	2920	</TD>
	2921	</TR>
	2922	<TR>
	2923	<TD WIDTH=126>
	2924	<P><A NAME="random_generator"></A><B>random_generator</B></P>
	2925	</TD>
	2926	<TD WIDTH=45>
	2927	<P>C * 20</P>
	2928	</TD>
	2929	<TD WIDTH=159>
	2930	<P><I>'numerical</I><BR><I>recipes'</I></P>
	2931	</TD>
	2932	<TD WIDTH=1280>
	2933	<P>Random number generator to be used for creating uniformly
	2934	distributed random numbers.
	2935	</P>
	2936	<P>It is used if random perturbations are to be imposed on the
	2937	velocity field or on the surface heat flux field (see
	2938	<A HREF="chapter_4.2.html#create_disturbances">create_disturbances</A>
	2939	and <A HREF="chapter_4.2.html#random_heatflux">random_heatflux</A>).
	2940	By default, the "Numerical Recipes" random number
	2941	generator is used. This one provides exactly the same order of
	2942	random numbers on all different machines and should be used in
	2943	particular for comparison runs.<BR><BR>Besides, a system-specific
	2944	generator is available ( <B>random_generator</B> =
	2945	<I>'system-specific')</I> which should particularly be used for
	2946	runs on vector parallel computers (NEC), because the default
	2947	generator cannot be vectorized and therefore significantly drops
	2948	down the code performance on these machines.</P>
	2949	<P><B>Note:</B><BR>Results from two otherwise identical model runs
	2950	will not be comparable one-to-one if they used different random
	2951	number generators.</P>
	2952	</TD>
	2953	</TR>
	2954	<TR>
	2955	<TD WIDTH=126>
	2956	<P><A NAME="random_heatflux"></A><B>random_heatflux</B></P>
	2957	</TD>
	2958	<TD WIDTH=45>
	2959	<P>L</P>
	2960	</TD>
	2961	<TD WIDTH=159>
	2962	<P><I>.F.</I></P>
	2963	</TD>
	2964	<TD WIDTH=1280>
	2965	<P>Parameter to impose random perturbations on the internal
	2966	two-dimensional near surface heat flux field <I>shf</I>.
	2967	</P>
	2968	<P>If a near surface heat flux is used as bottom boundary
	2969	condition (see <A HREF="#surface_heatflux">surface_heatflux</A>),
	2970	it is by default assumed to be horizontally homogeneous. Random
	2971	perturbations can be imposed on the internal two-dimensional heat
	2972	flux field <I>shf</I> by assigning <B>random_heatflux</B> = <I>.T.</I>.
	2973	The disturbed heat flux field is calculated by multiplying the
	2974	values at each mesh point with a normally distributed random
	2975	number with a mean value and standard deviation of 1. This is
	2976	repeated after every timestep.<BR><BR>In case of a non-flat
	2977	<A HREF="#topography">topography</A>, assigning
	2978	<B>random_heatflux</B> = <I>.T.</I> imposes random perturbations
	2979	on the combined heat flux field <I>shf</I> composed of
	2980	<A HREF="#surface_heatflux">surface_heatflux</A> at the bottom
	2981	surface and <A HREF="#wall_heatflux">wall_heatflux(0)</A> at the
	2982	topography top face.</P>
	2983	</TD>
	2984	</TR>
	2985	<TR>
	2986	<TD WIDTH=126>
	2987	<P><A NAME="recycling_width"></A><B>recycling_width</B></P>
	2988	</TD>
	2989	<TD WIDTH=45>
	2990	<P>R</P>
	2991	</TD>
	2992	<TD WIDTH=159>
	2993	<P><I>0.1 * <A HREF="#nx">nx</A> * <A HREF="#dx">dx</A></I></P>
	2994	</TD>
	2995	<TD WIDTH=1280>
	2996	<P>Distance of the recycling plane from the inflow boundary (in
	2997	m).<BR><BR>This parameter sets the horizontal extension (along the
	2998	direction of the main flow) of the so-called recycling domain
	2999	which is used to generate a turbulent inflow (see
	3000	<A HREF="#turbulent_inflow">turbulent_inflow</A>). <B>recycling_width</B>
	3001	must be larger than the grid spacing (dx) and smaller than the
	3002	length of the total domain (nx * dx).</P>
	3003	</TD>
	3004	</TR>
	3005	<TR>
	3006	<TD WIDTH=126>
	3007	<P><A NAME="rif_max"></A><B>rif_max</B></P>
	3008	</TD>
	3009	<TD WIDTH=45>
	3010	<P>R</P>
	3011	</TD>
	3012	<TD WIDTH=159>
	3013	<P><I>1.0</I></P>
	3014	</TD>
	3015	<TD WIDTH=1280>
	3016	<P>Upper limit of the flux-Richardson number.
	3017	</P>
	3018	<P>With the Prandtl layer switched on (see <A HREF="#prandtl_layer">prandtl_layer</A>),
	3019	flux-Richardson numbers (rif) are calculated for z=z<SUB>p</SUB>
	3020	(k=1) in the 3d-model (in the 1d model for all heights). Their
	3021	values in particular determine the values of the friction velocity
	3022	(1d- and 3d-model) and the values of the eddy diffusivity
	3023	(1d-model). With small wind velocities at the Prandtl layer top or
	3024	small vertical wind shears in the 1d-model, rif can take up
	3025	unrealistic large values. They are limited by an upper (<B>rif_max</B>)
	3026	and lower limit (see <A HREF="#rif_min">rif_min</A>) for the
	3027	flux-Richardson number. The condition <B>rif_max</B> > <B>rif_min</B>
	3028	must be met.</P>
	3029	</TD>
	3030	</TR>
	3031	<TR>
	3032	<TD WIDTH=126>
	3033	<P><A NAME="rif_min"></A><B>rif_min</B></P>
	3034	</TD>
	3035	<TD WIDTH=45>
	3036	<P>R</P>
	3037	</TD>
	3038	<TD WIDTH=159>
	3039	<P><I>- 5.0</I></P>
	3040	</TD>
	3041	<TD WIDTH=1280>
	3042	<P>Lower limit of the flux-Richardson number.
	3043	</P>
	3044	<P>For further explanations see <A HREF="#rif_max">rif_max</A>.
	3045	The condition <B>rif_max</B> > <B>rif_min </B>must be met.</P>
	3046	</TD>
	3047	</TR>
	3048	<TR>
	3049	<TD WIDTH=126>
	3050	<P><A NAME="roughness_length"></A><B>roughness_length</B></P>
	3051	</TD>
	3052	<TD WIDTH=45>
	3053	<P>R</P>
	3054	</TD>
	3055	<TD WIDTH=159>
	3056	<P><I>0.1</I></P>
	3057	</TD>
	3058	<TD WIDTH=1280>
	3059	<P>Roughness length (in m).
	3060	</P>
	3061	<P>This parameter is effective only in case that a Prandtl layer
	3062	is switched on (see <A HREF="#prandtl_layer">prandtl_layer</A>).</P>
	3063	</TD>
	3064	</TR>
	3065	<TR>
	3066	<TD WIDTH=126>
	3067	<P><A NAME="sa_surface"></A><B>sa_surface</B></P>
	3068	</TD>
	3069	<TD WIDTH=45>
	3070	<P>R</P>
	3071	</TD>
	3072	<TD WIDTH=159>
	3073	<P><I>35.0</I></P>
	3074	</TD>
	3075	<TD WIDTH=1280>
	3076	<P>Surface salinity (in psu). </P>
	3077	<P>This parameter only comes into effect for ocean runs (see
	3078	parameter <A HREF="#ocean">ocean</A>).
	3079	</P>
	3080	<P>This parameter assigns the value of the salinity <B>sa</B> at
	3081	the sea surface (k=nzt)<B>.</B> Starting from this value, the
	3082	initial vertical salinity profile is constructed from the surface
	3083	down to the bottom of the model (k=0) by
	3084	using <A HREF="#sa_vertical_gradient">sa_vertical_gradient</A>
	3085	and <A HREF="#sa_vertical_gradient_level">sa_vertical_gradient_level
	3086	</A>.</P>
	3087	</TD>
	3088	</TR>
	3089	<TR>
	3090	<TD WIDTH=126>
	3091	<P><A NAME="sa_vertical_gradient"></A><B>sa_vertical_gradient</B></P>
	3092	</TD>
	3093	<TD WIDTH=45>
	3094	<P>R(10)</P>
	3095	</TD>
	3096	<TD WIDTH=159>
	3097	<P><I>10 * 0.0</I></P>
	3098	</TD>
	3099	<TD WIDTH=1280>
	3100	<P>Salinity gradient(s) of the initial salinity profile (in psu /
	3101	100 m).
	3102	</P>
	3103	<P>This parameter only comes into effect for ocean runs (see
	3104	parameter <A HREF="#ocean">ocean</A>).</P>
	3105	<P>This salinity gradient holds starting from the height
	3106	level defined by <A HREF="#sa_vertical_gradient_level">sa_vertical_gradient_level</A>
	3107	(precisely: for all uv levels k where zu(k) <
	3108	sa_vertical_gradient_level, sa_init(k) is set: sa_init(k) =
	3109	sa_init(k+1) - dzu(k+1) * <B>sa_vertical_gradient</B>) down to the
	3110	bottom boundary or down to the next height level defined by
	3111	<A HREF="#sa_vertical_gradient_level">sa_vertical_gradient_level</A>.
	3112	A total of 10 different gradients for 11 height intervals (10
	3113	intervals if <A HREF="#sa_vertical_gradient_level">sa_vertical_gradient_level</A>(1)
	3114	= <I>0.0</I>) can be assigned. The surface salinity at k=nzt is
	3115	assigned via <A HREF="#sa_surface">sa_surface</A>.
	3116	</P>
	3117	<P>Example:
	3118	</P>
	3119	<UL>
	3120	<P><B>sa_vertical_gradient</B> = <I>1.0</I>, <I>0.5</I>,
	3121	<BR><B>sa_vertical_gradient_level</B> = <I>-500.0</I>, -<I>1000.0</I>,</P>
	3122	</UL>
	3123	<P>That defines the salinity to be constant down to z = -500.0 m
	3124	with a salinity given by <A HREF="#sa_surface">sa_surface</A>. For
	3125	-500.0 m < z <= -1000.0 m the salinity gradient is 1.0 psu /
	3126	100 m and for z < -1000.0 m down to the bottom boundary it is
	3127	0.5 psu / 100 m (it is assumed that the assigned height levels
	3128	correspond with uv levels).</P>
	3129	</TD>
	3130	</TR>
	3131	<TR>
	3132	<TD WIDTH=126>
	3133	<P><A NAME="sa_vertical_gradient_level"></A><B>sa_vertical_gradient_level</B></P>
	3134	</TD>
	3135	<TD WIDTH=45>
	3136	<P>R(10)</P>
	3137	</TD>
	3138	<TD WIDTH=159>
	3139	<P><I>10 * 0.0</I></P>
	3140	</TD>
	3141	<TD WIDTH=1280>
	3142	<P>Height level from which on the salinity gradient defined by
	3143	<A HREF="#sa_vertical_gradient">sa_vertical_gradient</A> is
	3144	effective (in m).
	3145	</P>
	3146	<P>This parameter only comes into effect for ocean runs (see
	3147	parameter <A HREF="#ocean">ocean</A>).</P>
	3148	<P>The height levels have to be assigned in descending order. The
	3149	default values result in a constant salinity profile regardless of
	3150	the values of <A HREF="#sa_vertical_gradient">sa_vertical_gradient</A>
	3151	(unless the bottom boundary of the model is lower than -100000.0
	3152	m). For the piecewise construction of salinity profiles see
	3153	<A HREF="#sa_vertical_gradient">sa_vertical_gradient</A>.</P>
	3154	</TD>
	3155	</TR>
	3156	<TR>
	3157	<TD WIDTH=126>
	3158	<P><A NAME="scalar_advec"></A><B>scalar_advec</B></P>
	3159	</TD>
	3160	<TD WIDTH=45>
	3161	<P>C * 10</P>
	3162	</TD>
	3163	<TD WIDTH=159>
	3164	<P><I>'pw-scheme'</I></P>
	3165	</TD>
	3166	<TD WIDTH=1280>
	3167	<P>Advection scheme to be used for the scalar quantities.
	3168	</P>
	3169	<P>The user can choose between the following schemes:</P>
	3170	<P><I>'pw-scheme'</I></P>
	3171	<P STYLE="margin-left: 0.42in; margin-bottom: 0in">The scheme of
	3172	Piascek and Williams (1970, J. Comp. Phys., 6, 392-405) with
	3173	central differences in the form C3 is used.<BR>If intermediate
	3174	Euler-timesteps are carried out in case of <A HREF="#timestep_scheme">timestep_scheme</A>
	3175	= <I>'leapfrog+euler'</I> the advection scheme is - for the
	3176	Euler-timestep - automatically switched to an upstream-scheme.
	3177	</P>
	3178	<P><BR><BR>
	3179	</P>
	3180	<P><I>'bc-scheme'</I></P>
	3181	<P STYLE="margin-left: 0.42in">The Bott scheme modified by Chlond
	3182	(1994, Mon. Wea. Rev., 122, 111-125). This is a conservative
	3183	monotonous scheme with very small numerical diffusion and
	3184	therefore very good conservation of scalar flow features. The
	3185	scheme however, is computationally very expensive both because it
	3186	is expensive itself and because it does (so far) not allow
	3187	specific code optimizations (e.g. cache optimization). Choice of
	3188	this scheme forces the Euler timestep scheme to be used for the
	3189	scalar quantities. For output of horizontally averaged profiles of
	3190	the resolved / total heat flux, <A HREF="chapter_4.2.html#data_output_pr">data_output_pr</A>
	3191	= <I>'wptBC'</I> / <I>'wptBC' </I>should be used, instead of the
	3192	standard profiles (<I>'wpt'</I> and <I>'wpt'</I>) because these
	3193	are too inaccurate with this scheme. However, for subdomain
	3194	analysis (see <A HREF="#statistic_regions">statistic_regions</A>)
	3195	exactly the reverse holds: here <I>'wptBC'</I> and <I>'wptBC'</I>
	3196	show very large errors and should not be used.<BR><BR>This scheme
	3197	is not allowed for non-cyclic lateral boundary conditions (see
	3198	<A HREF="#bc_lr">bc_lr</A> and <A HREF="#bc_ns">bc_ns</A>).</P>
	3199	<P><I>'ups-scheme'</I></P>
	3200	<P STYLE="margin-left: 0.42in">The upstream-spline-scheme is used
	3201	(see Mahrer and Pielke, 1978: Mon. Wea. Rev., 106, 818-830). In
	3202	opposite to the Piascek Williams scheme, this is characterized by
	3203	much better numerical features (less numerical diffusion, better
	3204	preservation of flux structures, e.g. vortices), but
	3205	computationally it is much more expensive. In addition, the use of
	3206	the Euler-timestep scheme is mandatory (<A HREF="#timestep_scheme">timestep_scheme</A>
	3207	= <I>'euler'</I>), i.e. the timestep accuracy is only first order.
	3208	For this reason the advection of momentum (see <A HREF="#momentum_advec">momentum_advec</A>)
	3209	should then also be carried out with the upstream-spline scheme,
	3210	because otherwise the momentum would be subject to large numerical
	3211	diffusion due to the upstream scheme.
	3212	</P>
	3213	<P STYLE="margin-left: 0.42in">Since the cubic splines used tend
	3214	to overshoot under certain circumstances, this effect must be
	3215	adjusted by suitable filtering and smoothing (see
	3216	<A HREF="#cut_spline_overshoot">cut_spline_overshoot</A>,
	3217	<A HREF="#long_filter_factor">long_filter_factor</A>,
	3218	<A HREF="#ups_limit_pt">ups_limit_pt</A>, <A HREF="#ups_limit_u">ups_limit_u</A>,
	3219	<A HREF="#ups_limit_v">ups_limit_v</A>, <A HREF="#ups_limit_w">ups_limit_w</A>).
	3220	This is always neccesssary for runs with stable stratification,
	3221	even if this stratification appears only in parts of the model
	3222	domain.
	3223	</P>
	3224	<P STYLE="margin-left: 0.42in">With stable stratification the
	3225	upstream-upline scheme also produces gravity waves with large
	3226	amplitude, which must be suitably damped (see
	3227	<A HREF="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</A>).</P>
	3228	<P STYLE="margin-left: 0.42in"><B>Important: </B>The
	3229	upstream-spline scheme is not implemented for humidity and passive
	3230	scalars (see <A HREF="#humidity">humidity</A> and
	3231	<A HREF="#passive_scalar">passive_scalar</A>) and requires the use
	3232	of a 2d-domain-decomposition. The last conditions severely
	3233	restricts code optimization on several machines leading to very
	3234	long execution times! This scheme is also not allowed for
	3235	non-cyclic lateral boundary conditions (see <A HREF="#bc_lr">bc_lr</A>
	3236	and <A HREF="#bc_ns">bc_ns</A>).</P>
	3237	<P><BR>A differing advection scheme can be choosed for the
	3238	subgrid-scale TKE using parameter <A HREF="#use_upstream_for_tke">use_upstream_for_tke</A>.</P>
	3239	</TD>
	3240	</TR>
	3241	<TR>
	3242	<TD WIDTH=126>
	3243	<P><A NAME="scalar_exchange_coefficient"></A><B>scalar_exchange_coefficient</B></P>
	3244	</TD>
	3245	<TD WIDTH=45>
	3246	<P>R</P>
	3247	</TD>
	3248	<TD WIDTH=159>
	3249	<P><I>0.0</I></P>
	3250	</TD>
	3251	<TD WIDTH=1280>
	3252	<P>Scalar exchange coefficient for a leaf (dimensionless).<BR><BR>This
	3253	parameter is only of importance in cases in that both,
	3254	<A HREF="../../../../../DEVELOPER_VERSION/chapter_4.1_adjusted.html#plant_canopy">plant_canopy</A>
	3255	and <A HREF="../../../../../DEVELOPER_VERSION/chapter_4.1_adjusted.html#passive_scalar">passive_scalar</A>,
	3256	are set <I>.T.</I>. The value of the scalar exchange coefficient
	3257	is required for the parametrisation of the sources and sinks of
	3258	scalar concentration due to the canopy.</P>
	3259	</TD>
	3260	</TR>
	3261	<TR>
	3262	<TD WIDTH=126>
	3263	<P><A NAME="statistic_regions"></A><B>statistic_regions</B></P>
	3264	</TD>
	3265	<TD WIDTH=45>
	3266	<P>I</P>
	3267	</TD>
	3268	<TD WIDTH=159>
	3269	<P><I>0</I></P>
	3270	</TD>
	3271	<TD WIDTH=1280>
	3272	<P>Number of additional user-defined subdomains for which
	3273	statistical analysis and corresponding output (profiles, time
	3274	series) shall be made.
	3275	</P>
	3276	<P>By default, vertical profiles and other statistical quantities
	3277	are calculated as horizontal and/or volume average of the total
	3278	model domain. Beyond that, these calculations can also be carried
	3279	out for subdomains which can be defined using the field <A HREF="chapter_3.5.3.html">rmask
	3280	</A>within the user-defined software (see <A HREF="chapter_3.5.3.html">chapter
	3281	3.5.3</A>). The number of these subdomains is determined with the
	3282	parameter <B>statistic_regions</B>. Maximum 9 additional
	3283	subdomains are allowed. The parameter <A HREF="chapter_4.3.html#region">region</A>
	3284	can be used to assigned names (identifier) to these subdomains
	3285	which are then used in the headers of the output files and plots.</P>
	3286	<P>If the default NetCDF output format is selected (see parameter
	3287	<A HREF="chapter_4.2.html#data_output_format">data_output_format</A>),
	3288	data for the total domain and all defined subdomains are output to
	3289	the same file(s) (<A HREF="chapter_3.4.html#DATA_1D_PR_NETCDF">DATA_1D_PR_NETCDF</A>,
	3290	<A HREF="chapter_3.4.html#DATA_1D_TS_NETCDF">DATA_1D_TS_NETCDF</A>).
	3291	In case of <B>statistic_regions</B> > <I>0</I>, data on the
	3292	file for the different domains can be distinguished by a suffix
	3293	which is appended to the quantity names. Suffix 0 means data for
	3294	the total domain, suffix 1 means data for subdomain 1, etc.</P>
	3295	<P>In case of <B>data_output_format</B> = <I>'profil'</I>,
	3296	individual local files for profiles (<A HREF="chapter_3.4.html#PLOT1D_DATA">PLOT1D_DATA</A>) are
	3297	created for each subdomain. The individual subdomain files differ
	3298	by their name (the number of the respective subdomain is attached,
	3299	e.g. PLOT1D_DATA_1). In this case the name of the file with the
	3300	data of the total domain is PLOT1D_DATA_0. If no subdomains are
	3301	declared (<B>statistic_regions</B> = <I>0</I>), the name
	3302	PLOT1D_DATA is used (this must be considered in the respective
	3303	file connection statements of the <B>mrun</B> configuration file).</P>
	3304	</TD>
	3305	</TR>
	3306	<TR>
	3307	<TD WIDTH=126>
	3308	<P><A NAME="surface_heatflux"></A><B>surface_heatflux</B></P>
	3309	</TD>
	3310	<TD WIDTH=45>
	3311	<P>R</P>
	3312	</TD>
	3313	<TD WIDTH=159>
	3314	<P><I>no prescribed<BR>heatflux</I></P>
	3315	</TD>
	3316	<TD WIDTH=1280>
	3317	<P>Kinematic sensible heat flux at the bottom surface (in K m/s).
	3318	</P>
	3319	<P>If a value is assigned to this parameter, the internal
	3320	two-dimensional surface heat flux field <I>shf</I> is initialized
	3321	with the value of <B>surface_heatflux</B> as bottom
	3322	(horizontally homogeneous) boundary condition for the temperature
	3323	equation. This additionally requires that a Neumann condition must
	3324	be used for the potential temperature (see <A HREF="#bc_pt_b">bc_pt_b</A>),
	3325	because otherwise the resolved scale may contribute to the surface
	3326	flux so that a constant value cannot be guaranteed. Also, changes
	3327	of the surface temperature (see <A HREF="#pt_surface_initial_change">pt_surface_initial_change</A>)
	3328	are not allowed. The parameter <A HREF="#random_heatflux">random_heatflux</A>
	3329	can be used to impose random perturbations on the (homogeneous)
	3330	surface heat flux field <I>shf</I>. </P>
	3331	<P>In case of a non-flat <A HREF="#topography">topography</A>, the
	3332	internal two-dimensional surface heat flux field <I>shf</I>
	3333	is initialized with the value of <B>surface_heatflux</B> at the
	3334	bottom surface and <A HREF="#wall_heatflux">wall_heatflux(0)</A>
	3335	at the topography top face. The parameter<A HREF="#random_heatflux">
	3336	random_heatflux</A> can be used to impose random perturbations on
	3337	this combined surface heat flux field <I>shf</I>.
	3338	</P>
	3339	<P>If no surface heat flux is assigned, <I>shf</I> is calculated
	3340	at each timestep by u<SUB></SUB> theta<SUB>*</SUB> (of course
	3341	only with <A HREF="#prandtl_layer">prandtl_layer</A> switched on).
	3342	Here, u<SUB></SUB> and theta<SUB></SUB> are calculated from the
	3343	Prandtl law assuming logarithmic wind and temperature profiles
	3344	between k=0 and k=1. In this case a Dirichlet condition (see
	3345	<A HREF="#bc_pt_b">bc_pt_b</A>) must be used as bottom boundary
	3346	condition for the potential temperature.</P>
	3347	<P>See also <A HREF="#top_heatflux">top_heatflux</A>.</P>
	3348	</TD>
	3349	</TR>
	3350	<TR>
	3351	<TD WIDTH=126>
	3352	<P><A NAME="surface_pressure"></A><B>surface_pressure</B></P>
	3353	</TD>
	3354	<TD WIDTH=45>
	3355	<P>R</P>
	3356	</TD>
	3357	<TD WIDTH=159>
	3358	<P><I>1013.25</I></P>
	3359	</TD>
	3360	<TD WIDTH=1280>
	3361	<P>Atmospheric pressure at the surface (in hPa).
	3362	</P>
	3363	<P>Starting from this surface value, the vertical pressure profile
	3364	is calculated once at the beginning of the run assuming a
	3365	neutrally stratified atmosphere. This is needed for converting
	3366	between the liquid water potential temperature and the potential
	3367	temperature (see <A HREF="#cloud_physics">cloud_physics</A>).</P>
	3368	</TD>
	3369	</TR>
	3370	<TR>
	3371	<TD WIDTH=126>
	3372	<P><A NAME="surface_scalarflux"></A><B>surface_scalarflux</B></P>
	3373	</TD>
	3374	<TD WIDTH=45>
	3375	<P>R</P>
	3376	</TD>
	3377	<TD WIDTH=159>
	3378	<P><I>0.0</I></P>
	3379	</TD>
	3380	<TD WIDTH=1280>
	3381	<P>Scalar flux at the surface (in kg/(m<SUP>2</SUP> s)).
	3382	</P>
	3383	<P>If a non-zero value is assigned to this parameter, the
	3384	respective scalar flux value is used as bottom (horizontally
	3385	homogeneous) boundary condition for the scalar concentration
	3386	equation. This additionally requires that a Neumann condition
	3387	must be used for the scalar concentration (see <A HREF="#bc_s_b">bc_s_b</A>),
	3388	because otherwise the resolved scale may contribute to the surface
	3389	flux so that a constant value cannot be guaranteed. Also, changes
	3390	of the surface scalar concentration (see <A HREF="#s_surface_initial_change">s_surface_initial_change</A>)
	3391	are not allowed.
	3392	</P>
	3393	<P>If no surface scalar flux is assigned (<B>surface_scalarflux</B>
	3394	= <I>0.0</I>), it is calculated at each timestep by u<SUB>*</SUB>
	3395	* s<SUB>*</SUB> (of course only with Prandtl layer switched on).
	3396	Here, s<SUB>*</SUB> is calculated from the Prandtl law assuming a
	3397	logarithmic scalar concentration profile between k=0 and k=1. In
	3398	this case a Dirichlet condition (see <A HREF="#bc_s_b">bc_s_b</A>)
	3399	must be used as bottom boundary condition for the scalar
	3400	concentration.</P>
	3401	</TD>
	3402	</TR>
	3403	<TR>
	3404	<TD WIDTH=126>
	3405	<P><A NAME="surface_waterflux"></A><B>surface_waterflux</B></P>
	3406	</TD>
	3407	<TD WIDTH=45>
	3408	<P>R</P>
	3409	</TD>
	3410	<TD WIDTH=159>
	3411	<P><I>0.0</I></P>
	3412	</TD>
	3413	<TD WIDTH=1280>
	3414	<P>Kinematic water flux near the surface (in m/s).
	3415	</P>
	3416	<P>If a non-zero value is assigned to this parameter, the
	3417	respective water flux value is used as bottom (horizontally
	3418	homogeneous) boundary condition for the humidity equation. This
	3419	additionally requires that a Neumann condition must be used for
	3420	the specific humidity / total water content (see <A HREF="#bc_q_b">bc_q_b</A>),
	3421	because otherwise the resolved scale may contribute to the surface
	3422	flux so that a constant value cannot be guaranteed. Also, changes
	3423	of the surface humidity (see <A HREF="#q_surface_initial_change">q_surface_initial_change</A>)
	3424	are not allowed.</P>
	3425	<P>If no surface water flux is assigned (<B>surface_waterflux</B>
	3426	= <I>0.0</I>), it is calculated at each timestep by u<SUB>*</SUB>
	3427	* q<SUB>*</SUB> (of course only with Prandtl layer switched on).
	3428	Here, q<SUB>*</SUB> is calculated from the Prandtl law assuming a
	3429	logarithmic temperature profile between k=0 and k=1. In this case
	3430	a Dirichlet condition (see <A HREF="#bc_q_b">bc_q_b</A>) must be
	3431	used as the bottom boundary condition for the humidity.</P>
	3432	</TD>
	3433	</TR>
	3434	<TR>
	3435	<TD WIDTH=126>
	3436	<P><A NAME="s_surface"></A><B>s_surface</B></P>
	3437	</TD>
	3438	<TD WIDTH=45>
	3439	<P>R</P>
	3440	</TD>
	3441	<TD WIDTH=159>
	3442	<P><I>0.0</I></P>
	3443	</TD>
	3444	<TD WIDTH=1280>
	3445	<P>Surface value of the passive scalar (in kg/m<SUP>3</SUP>). </P>
	3446	<P>This parameter assigns the value of the passive scalar s at the
	3447	surface (k=0)<B>.</B> Starting from this value, the initial
	3448	vertical scalar concentration profile is constructed with<A HREF="#s_vertical_gradient">
	3449	s_vertical_gradient</A> and <A HREF="#s_vertical_gradient_level">s_vertical_gradient_level</A>.</P>
	3450	</TD>
	3451	</TR>
	3452	<TR>
	3453	<TD WIDTH=126>
	3454	<P><A NAME="s_surface_initial_change"></A><B>s_surface_initial</B>
	3455	<BR><B>_change</B></P>
	3456	</TD>
	3457	<TD WIDTH=45>
	3458	<P>R</P>
	3459	</TD>
	3460	<TD WIDTH=159>
	3461	<P><I>0.0</I></P>
	3462	</TD>
	3463	<TD WIDTH=1280>
	3464	<P>Change in surface scalar concentration to be made at the
	3465	beginning of the 3d run (in kg/m<SUP>3</SUP>).
	3466	</P>
	3467	<P>If <B>s_surface_initial_change</B> is set to a non-zero
	3468	value, the near surface scalar flux is not allowed to be given
	3469	simultaneously (see <A HREF="#surface_scalarflux">surface_scalarflux</A>).</P>
	3470	</TD>
	3471	</TR>
	3472	<TR>
	3473	<TD WIDTH=126>
	3474	<P><A NAME="s_vertical_gradient"></A><B>s_vertical_gradient</B></P>
	3475	</TD>
	3476	<TD WIDTH=45>
	3477	<P>R (10)</P>
	3478	</TD>
	3479	<TD WIDTH=159>
	3480	<P><I>10 * 0.0</I></P>
	3481	</TD>
	3482	<TD WIDTH=1280>
	3483	<P>Scalar concentration gradient(s) of the initial scalar
	3484	concentration profile (in kg/m<SUP>3 </SUP>/ 100 m).
	3485	</P>
	3486	<P>The scalar gradient holds starting from the height level
	3487	defined by <A HREF="#s_vertical_gradient_level">s_vertical_gradient_level
	3488	</A>(precisely: for all uv levels k, where zu(k) >
	3489	s_vertical_gradient_level, s_init(k) is set: s_init(k) =
	3490	s_init(k-1) + dzu(k) * <B>s_vertical_gradient</B>) up to the top
	3491	boundary or up to the next height level defined by
	3492	<A HREF="#s_vertical_gradient_level">s_vertical_gradient_level</A>.
	3493	A total of 10 different gradients for 11 height intervals (10
	3494	intervals if <A HREF="#s_vertical_gradient_level">s_vertical_gradient_level</A>(1)
	3495	= <I>0.0</I>) can be assigned. The surface scalar value is
	3496	assigned via <A HREF="#s_surface">s_surface</A>.</P>
	3497	<P>Example:
	3498	</P>
	3499	<UL>
	3500	<P><B>s_vertical_gradient</B> = <I>0.1</I>, <I>0.05</I>,
	3501	<BR><B>s_vertical_gradient_level</B> = <I>500.0</I>, <I>1000.0</I>,</P>
	3502	</UL>
	3503	<P>That defines the scalar concentration to be constant with
	3504	height up to z = 500.0 m with a value given by <A HREF="#s_surface">s_surface</A>.
	3505	For 500.0 m < z <= 1000.0 m the scalar gradient is 0.1 kg/m<SUP>3
	3506	</SUP>/ 100 m and for z > 1000.0 m up to the top boundary it is
	3507	0.05 kg/m<SUP>3 </SUP>/ 100 m (it is assumed that the assigned
	3508	height levels correspond with uv levels).</P>
	3509	</TD>
	3510	</TR>
	3511	<TR>
	3512	<TD WIDTH=126>
	3513	<P><A NAME="s_vertical_gradient_level"></A><B>s_vertical_gradient_</B>
	3514	<BR><B>level</B></P>
	3515	</TD>
	3516	<TD WIDTH=45>
	3517	<P>R (10)</P>
	3518	</TD>
	3519	<TD WIDTH=159>
	3520	<P><I>10 *</I> <I>0.0</I></P>
	3521	</TD>
	3522	<TD WIDTH=1280>
	3523	<P>Height level from which on the scalar gradient defined by
	3524	<A HREF="#s_vertical_gradient">s_vertical_gradient</A> is
	3525	effective (in m).
	3526	</P>
	3527	<P>The height levels are to be assigned in ascending order. The
	3528	default values result in a scalar concentration constant with
	3529	height regardless of the values of <A HREF="#s_vertical_gradient">s_vertical_gradient</A>
	3530	(unless the top boundary of the model is higher than 100000.0 m).
	3531	For the piecewise construction of scalar concentration profiles
	3532	see <A HREF="#s_vertical_gradient">s_vertical_gradient</A>.</P>
	3533	</TD>
	3534	</TR>
	3535	<TR>
	3536	<TD WIDTH=126>
	3537	<P><A NAME="timestep_scheme"></A><B>timestep_scheme</B></P>
	3538	</TD>
	3539	<TD WIDTH=45>
	3540	<P>C * 20</P>
	3541	</TD>
	3542	<TD WIDTH=159>
	3543	<P><I>'runge</I><BR><I>kutta-3'</I></P>
	3544	</TD>
	3545	<TD WIDTH=1280>
	3546	<P>Time step scheme to be used for the integration of the
	3547	prognostic variables.
	3548	</P>
	3549	<P>The user can choose between the following schemes:</P>
	3550	<P><I>'runge-kutta-3'</I></P>
	3551	<P STYLE="margin-left: 0.42in">Third order Runge-Kutta
	3552	scheme.<BR>This scheme requires the use of <A HREF="#momentum_advec">momentum_advec</A>
	3553	= <A HREF="#scalar_advec">scalar_advec</A> = '<I>pw-scheme'</I>.
	3554	Please refer to the <A HREF="../tec/numerik.heiko/zeitschrittverfahren.pdf">documentation
	3555	on PALM's time integration schemes (28p., in German)</A> fur
	3556	further details.</P>
	3557	<P><I>'runge-kutta-2'</I></P>
	3558	<P STYLE="margin-left: 0.42in; margin-bottom: 0in">Second order
	3559	Runge-Kutta scheme.<BR>For special features see <B>timestep_scheme</B>
	3560	= '<I>runge-kutta-3'</I>.</P>
	3561	<P><BR><I>'leapfrog'</I></P>
	3562	<P STYLE="margin-left: 0.42in; margin-bottom: 0in">Second order
	3563	leapfrog scheme.<BR>Although this scheme requires a constant
	3564	timestep (because it is centered in time),  is even applied
	3565	in case of changes in timestep. Therefore, only small changes of
	3566	the timestep are allowed (see <A HREF="#dt">dt</A>). However, an
	3567	Euler timestep is always used as the first timestep of an initiali
	3568	run. When using the Bott-Chlond scheme for scalar advection (see
	3569	<A HREF="#scalar_advec">scalar_advec</A>), the prognostic equation
	3570	for potential temperature will be calculated with the Euler
	3571	scheme, although the leapfrog scheme is switched on.  <BR>The
	3572	leapfrog scheme must not be used together with the upstream-spline
	3573	scheme for calculating the advection (see <A HREF="#scalar_advec">scalar_advec</A>
	3574	= '<I>ups-scheme'</I> and <A HREF="#momentum_advec">momentum_advec</A>
	3575	= '<I>ups-scheme'</I>).</P>
	3576	<P><BR><I>'leapfrog+euler'</I></P>
	3577	<P STYLE="margin-left: 0.42in; margin-bottom: 0in">The leapfrog
	3578	scheme is used, but after each change of a timestep an Euler
	3579	timestep is carried out. Although this method is theoretically
	3580	correct (because the pure leapfrog method does not allow timestep
	3581	changes), the divergence of the velocity field (after applying the
	3582	pressure solver) may be significantly larger than with <I>'leapfrog'</I>.</P>
	3583	<P><BR><I>'euler'</I></P>
	3584	<P STYLE="margin-left: 0.42in; margin-bottom: 0in">First order
	3585	Euler scheme.  <BR>The Euler scheme must be used when
	3586	treating the advection terms with the upstream-spline scheme (see
	3587	<A HREF="#scalar_advec">scalar_advec</A> = <I>'ups-scheme'</I> and
	3588	<A HREF="#momentum_advec">momentum_advec</A> = <I>'ups-scheme'</I>).</P>
	3589	<P STYLE="margin-bottom: 0in"><BR><BR>A differing timestep scheme
	3590	can be choosed for the subgrid-scale TKE using parameter
	3591	<A HREF="#use_upstream_for_tke">use_upstream_for_tke</A>.</P>
	3592	</TD>
	3593	</TR>
	3594	<TR>
	3595	<TD WIDTH=126>
	3596	<P ALIGN=LEFT><A NAME="topography"></A><B>topography</B></P>
	3597	</TD>
	3598	<TD WIDTH=45>
	3599	<P>C * 40</P>
	3600	</TD>
	3601	<TD WIDTH=159>
	3602	<P><I>'flat'</I></P>
	3603	</TD>
	3604	<TD WIDTH=1280>
	3605	<P>Topography mode.
	3606	</P>
	3607	<P>The user can choose between the following modes:</P>
	3608	<P><I>'flat'</I></P>
	3609	<P STYLE="margin-left: 0.42in">Flat surface.</P>
	3610	<P><I>'single_building'</I></P>
	3611	<P STYLE="margin-left: 0.42in">Flow around a single
	3612	rectangular building mounted on a flat surface.<BR>The building
	3613	size and location can be specified by the parameters
	3614	<A HREF="#building_height">building_height</A>, <A HREF="#building_length_x">building_length_x</A>,
	3615	<A HREF="#building_length_y">building_length_y</A>,
	3616	<A HREF="#building_wall_left">building_wall_left</A> and
	3617	<A HREF="#building_wall_south">building_wall_south</A>.</P>
	3618	<P><I>'single_street_canyon'</I></P>
	3619	<P STYLE="margin-left: 0.42in; margin-bottom: 0in">Flow over a
	3620	single, quasi-2D street canyon of infinite length oriented either
	3621	in x- or in y-direction.<BR>The canyon size, orientation and
	3622	location can be specified by the parameters <A HREF="#canyon_height">canyon_height</A>
	3623	plus <B>either</B> <A HREF="#canyon_width_x">canyon_width_x</A>
	3624	and <A HREF="#canyon_wall_left">canyon_wall_left</A> <B>or</B>
	3625	<A HREF="#canyon_width_y">canyon_width_y</A> and
	3626	<A HREF="#canyon_wall_south">canyon_wall_south</A>.</P>
	3627	<P> </P>
	3628	<P><I>'read_from_file'</I></P>
	3629	<P STYLE="margin-left: 0.42in; margin-bottom: 0in">Flow around
	3630	arbitrary topography.<BR>This mode requires the input file
	3631	<A HREF="chapter_3.4.html#TOPOGRAPHY_DATA">TOPOGRAPHY_DATA</A><FONT COLOR="#000000">.
	3632	This file contains the arbitrary topography height
	3633	information in m. These data must exactly match the
	3634	horizontal grid.</FONT></P>
	3635	<P STYLE="margin-bottom: 0in"><I><BR></I><FONT COLOR="#000000">Alternatively,
	3636	the user may add code to the user interface subroutine
	3637	<A HREF="chapter_3.5.1.html#user_init_grid">user_init_grid</A> to
	3638	allow further topography modes. </FONT>These require to explicitly
	3639	set the <A HREF="#topography_grid_convention">topography_grid_convention</A> to
	3640	either <I>'cell_edge'</I> or <I>'cell_center'</I>.<BR><FONT COLOR="#000000"><BR>Non-flat
	3641	</FONT><FONT COLOR="#000000"><B>topography</B></FONT><FONT COLOR="#000000">
	3642	modes may assign a</FONT> kinematic sensible<FONT COLOR="#000000">
	3643	<A HREF="#wall_heatflux">wall_heatflux</A> at the five topography
	3644	faces.</FONT><BR><FONT COLOR="#000000"><BR>All non-flat </FONT><FONT COLOR="#000000"><B>topography</B></FONT><FONT COLOR="#000000">
	3645	modes </FONT>require the use of <A HREF="#momentum_advec">momentum_advec</A>
	3646	= <A HREF="#scalar_advec">scalar_advec</A> = '<I>pw-scheme'</I>,
	3647	<A HREF="chapter_4.2.html#psolver">psolver</A> /= <I>'sor'</I>,
	3648	<A HREF="#alpha_surface">alpha_surface</A> =
	3649	0.0, <A HREF="#galilei_transformation">galilei_transformation</A>
	3650	= <I>.F.</I>, <A HREF="#cloud_physics">cloud_physics </A>
	3651	= <I>.F.</I>,  <A HREF="#cloud_droplets">cloud_droplets</A> =
	3652	<I>.F.</I>,  <A HREF="#humidity">humidity</A> = <I>.F.</I>,
	3653	and <A HREF="#prandtl_layer">prandtl_layer</A> = .T..<BR><FONT COLOR="#000000"><BR>Note
	3654	that an inclined model domain requires the use of </FONT><FONT COLOR="#000000"><B>topography</B></FONT><FONT COLOR="#000000">
	3655	= </FONT><FONT COLOR="#000000"><I>'flat'</I></FONT><FONT COLOR="#000000">
	3656	and a nonzero </FONT><A HREF="#alpha_surface">alpha_surface</A>.</P>
	3657	</TD>
	3658	</TR>
	3659	<TR>
	3660	<TD WIDTH=126>
	3661	<P><A NAME="topography_grid_convention"></A><B>topography_grid_</B><BR><B>convention</B></P>
	3662	</TD>
	3663	<TD WIDTH=45>
	3664	<P>C*11</P>
	3665	</TD>
	3666	<TD WIDTH=159>
	3667	<P><I>default depends on value of <A HREF="#topography">topography</A>;
	3668	see text for details</I></P>
	3669	</TD>
	3670	<TD WIDTH=1280>
	3671	<P>Convention for defining the topography grid.<BR><BR>Possible
	3672	values are</P>
	3673	<UL>
	3674	<LI><P STYLE="margin-bottom: 0in"><I>'cell_edge': </I>the
	3675	distance between cell edges defines the extent of topography.
	3676	This setting is normally for <I>generic topographies</I>, i.e.
	3677	topographies that are constructed using length parameters. For
	3678	example, <A HREF="#topography">topography</A> = <I>'single_building'</I>
	3679	is constructed using <A HREF="#building_length_x">building_length_x</A>
	3680	and <A HREF="#building_length_y">building_length_y</A>. The
	3681	advantage of this setting is that the actual size of generic
	3682	topography is independent of the grid size, provided that the
	3683	length parameters are an integer multiple of the grid lengths <A HREF="#dx">dx</A>
	3684	and <A HREF="#dy">dy</A>. This is convenient for
	3685	resolution parameter studies.</P>
	3686	<LI><P><I>'cell_center': </I>the number of topography cells
	3687	define the extent of topography. This setting is normally for
	3688	<I>rastered real topographies</I> derived from digital elevation
	3689	models. For example, <A HREF="#topography">topography</A> =
	3690	<I>'read_from_file'</I> is constructed using the input file
	3691	<A HREF="chapter_3.4.html#TOPOGRAPHY_DATA">TOPOGRAPHY_DATA</A><FONT COLOR="#000000">. </FONT>The
	3692	advantage of this setting is that the rastered topography
	3693	cells of the input file are directly mapped to topography grid
	3694	boxes in PALM.
	3695	</P>
	3696	</UL>
	3697	<P>The example files <CODE><FONT SIZE=4>example_topo_file</FONT></CODE>
	3698	and <CODE><FONT SIZE=4>example_building</FONT></CODE> in
	3699	<CODE><FONT SIZE=4>trunk/EXAMPLES/</FONT></CODE> illustrate the
	3700	difference between both approaches. Both examples simulate a
	3701	single building and yield the same results. The former uses a
	3702	rastered topography input file with <I>'cell_center'</I>
	3703	convention, the latter applies a generic topography with
	3704	<I>'cell_edge'</I> convention.<BR><BR>The default value is</P>
	3705	<UL>
	3706	<LI><P STYLE="margin-bottom: 0in"><I>'cell_edge' </I>if
	3707	<A HREF="#topography">topography</A> = <I>'single_building'</I>
	3708	or <I>'single_street_canyon'</I>,</P>
	3709	<LI><P STYLE="margin-bottom: 0in"><I>'cell_center'</I> if
	3710	<A HREF="#topography">topography</A> = <I>'read_from_file'</I>,</P>
	3711	<LI><P><I>none (' '</I> ) otherwise, leading to an abort
	3712	if <B>topography_grid_convention</B> is not set.</P>
	3713	</UL>
	3714	<P>This means that
	3715	</P>
	3716	<UL>
	3717	<LI><P STYLE="margin-bottom: 0in">For PALM simulations using a
	3718	<I>user-defined topography</I>, the <B>topography_grid_convention</B>
	3719	must be explicitly set to either <I>'cell_edge'</I> or
	3720	<I>'cell_center'</I>.</P>
	3721	<LI><P>For PALM simulations using a <I>standard topography</I>
	3722	<I>('single_building'</I>, <I>'single_street_canyon'</I> or
	3723	<I>'read_from_file')</I>, it is possible but not required to set
	3724	the  <B>topography_grid_convention</B> because appropriate
	3725	default values apply.</P>
	3726	</UL>
	3727	</TD>
	3728	</TR>
	3729	<TR>
	3730	<TD WIDTH=126>
	3731	<P><A NAME="top_heatflux"></A><B>top_heatflux</B></P>
	3732	</TD>
	3733	<TD WIDTH=45>
	3734	<P>R</P>
	3735	</TD>
	3736	<TD WIDTH=159>
	3737	<P><I>no prescribed<BR>heatflux</I></P>
	3738	</TD>
	3739	<TD WIDTH=1280>
	3740	<P>Kinematic sensible heat flux at the top boundary (in K m/s).
	3741	</P>
	3742	<P>If a value is assigned to this parameter, the internal
	3743	two-dimensional surface heat flux field <FONT FACE="monospace">tswst</FONT>
	3744	is initialized with the value of <B>top_heatflux</B> as top
	3745	(horizontally homogeneous) boundary condition for the temperature
	3746	equation. This additionally requires that a Neumann condition must
	3747	be used for the potential temperature (see <A HREF="#bc_pt_t">bc_pt_t</A>),
	3748	because otherwise the resolved scale may contribute to the top
	3749	flux so that a constant flux value cannot be guaranteed. </P>
	3750	<P><B>Note:</B><BR>The application of a top heat flux additionally
	3751	requires the setting of initial parameter <A HREF="#use_top_fluxes">use_top_fluxes</A>
	3752	= .T..
	3753	</P>
	3754	<P>No Prandtl-layer is available at the top boundary so far.</P>
	3755	<P>See also <A HREF="#surface_heatflux">surface_heatflux</A>.</P>
	3756	</TD>
	3757	</TR>
	3758	<TR>
	3759	<TD WIDTH=126>
	3760	<P><A NAME="top_momentumflux_u"></A><B>top_momentumflux_u</B></P>
	3761	</TD>
	3762	<TD WIDTH=45>
	3763	<P>R</P>
	3764	</TD>
	3765	<TD WIDTH=159>
	3766	<P><I>no prescribed momentumflux</I></P>
	3767	</TD>
	3768	<TD WIDTH=1280>
	3769	<P>Momentum flux along x at the top boundary (in m2/s2).</P>
	3770	<P>If a value is assigned to this parameter, the internal
	3771	two-dimensional u-momentum flux field <FONT FACE="monospace">uswst</FONT>
	3772	is initialized with the value of <B>top_momentumflux_u</B> as top
	3773	(horizontally homogeneous) boundary condition for the u-momentum
	3774	equation.</P>
	3775	<P><B>Notes:</B><BR>The application of a top momentum flux
	3776	additionally requires the setting of initial parameter
	3777	<A HREF="#use_top_fluxes">use_top_fluxes</A> = .T.. Setting of
	3778	<B>top_momentumflux_u</B> requires setting of <A HREF="#top_momentumflux_v">top_momentumflux_v</A>
	3779	also.</P>
	3780	<P>A Neumann condition should be used for the u velocity
	3781	component (see <A HREF="#bc_uv_t">bc_uv_t</A>), because otherwise
	3782	the resolved scale may contribute to the top flux so that a
	3783	constant flux value cannot be guaranteed. </P>
	3784	<P>No Prandtl-layer is available at the top boundary so far.</P>
	3785	<P>The <A HREF="chapter_3.8.html">coupled</A> ocean parameter
	3786	file <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN_O</FONT></A>
	3787	should include dummy REAL value assignments to both
	3788	<A HREF="#top_momentumflux_u">top_momentumflux_u</A>
	3789	and <A HREF="#top_momentumflux_v">top_momentumflux_v</A>
	3790	(e.g. top_momentumflux_u = 0.0, top_momentumflux_v = 0.0) to
	3791	enable the momentum flux coupling.</P>
	3792	</TD>
	3793	</TR>
	3794	<TR>
	3795	<TD WIDTH=126>
	3796	<P><A NAME="top_momentumflux_v"></A><B>top_momentumflux_v</B></P>
	3797	</TD>
	3798	<TD WIDTH=45>
	3799	<P>R</P>
	3800	</TD>
	3801	<TD WIDTH=159>
	3802	<P><I>no prescribed momentumflux</I></P>
	3803	</TD>
	3804	<TD WIDTH=1280>
	3805	<P>Momentum flux along y at the top boundary (in m2/s2).</P>
	3806	<P>If a value is assigned to this parameter, the internal
	3807	two-dimensional v-momentum flux field <FONT FACE="monospace">vswst</FONT>
	3808	is initialized with the value of <B>top_momentumflux_v</B> as top
	3809	(horizontally homogeneous) boundary condition for the v-momentum
	3810	equation.</P>
	3811	<P><B>Notes:</B><BR>The application of a top momentum flux
	3812	additionally requires the setting of initial parameter
	3813	<A HREF="#use_top_fluxes">use_top_fluxes</A> = .T.. Setting of
	3814	<B>top_momentumflux_v</B> requires setting of <A HREF="#top_momentumflux_u">top_momentumflux_u</A>
	3815	also.</P>
	3816	<P>A Neumann condition should be used for the v velocity
	3817	component (see <A HREF="#bc_uv_t">bc_uv_t</A>), because otherwise
	3818	the resolved scale may contribute to the top flux so that a
	3819	constant flux value cannot be guaranteed. </P>
	3820	<P>No Prandtl-layer is available at the top boundary so far.</P>
	3821	<P>The <A HREF="chapter_3.8.html">coupled</A> ocean parameter
	3822	file <A HREF="chapter_3.4.html#PARIN"><FONT SIZE=2>PARIN_O</FONT></A>
	3823	should include dummy REAL value assignments to both
	3824	<A HREF="#top_momentumflux_u">top_momentumflux_u</A>
	3825	and <A HREF="#top_momentumflux_v">top_momentumflux_v</A>
	3826	(e.g. top_momentumflux_u = 0.0, top_momentumflux_v = 0.0) to
	3827	enable the momentum flux coupling.</P>
	3828	</TD>
	3829	</TR>
	3830	<TR>
	3831	<TD WIDTH=126>
	3832	<P><A NAME="top_salinityflux"></A><B>top_salinityflux</B></P>
	3833	</TD>
	3834	<TD WIDTH=45>
	3835	<P>R</P>
	3836	</TD>
	3837	<TD WIDTH=159>
	3838	<P><I>no prescribed<BR>salinityflux</I></P>
	3839	</TD>
	3840	<TD WIDTH=1280>
	3841	<P>Kinematic salinity flux at the top boundary, i.e. the sea
	3842	surface (in psu m/s).
	3843	</P>
	3844	<P>This parameter only comes into effect for ocean runs (see
	3845	parameter <A HREF="#ocean">ocean</A>).</P>
	3846	<P>If a value is assigned to this parameter, the internal
	3847	two-dimensional surface heat flux field <FONT FACE="monospace">saswst</FONT>
	3848	is initialized with the value of <B>top_salinityflux</B> as
	3849	top (horizontally homogeneous) boundary condition for the salinity
	3850	equation. This additionally requires that a Neumann condition must
	3851	be used for the salinity (see <A HREF="#bc_sa_t">bc_sa_t</A>),
	3852	because otherwise the resolved scale may contribute to the top
	3853	flux so that a constant flux value cannot be guaranteed. </P>
	3854	<P><B>Note:</B><BR>The application of a salinity flux at the model
	3855	top additionally requires the setting of initial parameter
	3856	<A HREF="#use_top_fluxes">use_top_fluxes</A> = .T..
	3857	</P>
	3858	<P>See also <A HREF="#bottom_salinityflux">bottom_salinityflux</A>.</P>
	3859	</TD>
	3860	</TR>
	3861	<TR>
	3862	<TD WIDTH=126>
	3863	<P><A NAME="turbulent_inflow"></A><B>turbulent_inflow</B></P>
	3864	</TD>
	3865	<TD WIDTH=45>
	3866	<P>L</P>
	3867	</TD>
	3868	<TD WIDTH=159>
	3869	<P><I>.F.</I></P>
	3870	</TD>
	3871	<TD WIDTH=1280>
	3872	<P>Generates a turbulent inflow at side boundaries using a
	3873	turbulence recycling method.<BR><BR>Turbulent inflow is realized
	3874	using the turbulence recycling method from Lund et al. (1998, J.
	3875	Comp. Phys., <B>140</B>, 233-258) modified by Kataoka and Mizuno
	3876	(2002, Wind and Structures, <B>5</B>, 379-392).<BR><BR>A turbulent
	3877	inflow requires Dirichlet conditions at the respective inflow
	3878	boundary. <B>So far, a turbulent inflow is realized from the left
	3879	(west) side only, i.e. <A HREF="#bc_lr">bc_lr</A></B> <B>=</B>
	3880	<I><B>'dirichlet/radiation'</B></I> <B>is required!</B><BR><BR>The
	3881	initial (quasi-stationary) turbulence field should be generated by
	3882	a precursor run and used by setting <A HREF="#initializing_actions">initializing_actions</A>
	3883	= <I>'cyclic_fill'</I>.<BR><BR>The distance of the recycling plane
	3884	from the inflow boundary can be set with parameter
	3885	<A HREF="#recycling_width">recycling_width</A>. The heigth above
	3886	ground above which the turbulence signal is not used for recycling
	3887	and the width of the layer within the magnitude of the
	3888	turbulence signal is damped from 100% to 0% can be set with
	3889	parameters <A HREF="#inflow_damping_height">inflow_damping_height</A>
	3890	and <A HREF="#inflow_damping_width">inflow_damping_width</A>.<BR><BR>The
	3891	detailed setup for a turbulent inflow is described in <A HREF="chapter_3.9.html">chapter
	3892	3.9</A>.</P>
	3893	</TD>
	3894	</TR>
	3895	<TR>
	3896	<TD WIDTH=126>
	3897	<P><A NAME="u_bulk"></A><B>u_bulk</B></P>
	3898	</TD>
	3899	<TD WIDTH=45>
	3900	<P>R</P>
	3901	</TD>
	3902	<TD WIDTH=159>
	3903	<P><I>0.0</I></P>
	3904	</TD>
	3905	<TD WIDTH=1280>
	3906	<P>u-component of the predefined bulk velocity (in m/s).<BR><BR>This
	3907	parameter comes into effect if <A HREF="#conserve_volume_flow">conserve_volume_flow</A>
	3908	= <I>.T.</I> and <A HREF="#conserve_volume_flow_mode">conserve_volume_flow_mode</A>
	3909	= <I>'bulk_velocity'</I>.</P>
	3910	</TD>
	3911	</TR>
	3912	<TR>
	3913	<TD WIDTH=126>
	3914	<P><A NAME="ug_surface"></A><B>ug_surface</B></P>
	3915	</TD>
	3916	<TD WIDTH=45>
	3917	<P>R</P>
	3918	</TD>
	3919	<TD WIDTH=159>
	3920	<P><I>0.0</I></P>
	3921	</TD>
	3922	<TD WIDTH=1280>
	3923	<P>u-component of the geostrophic wind at the surface (in
	3924	m/s).<BR><BR>This parameter assigns the value of the u-component
	3925	of the geostrophic wind (ug) at the surface (k=0). Starting from
	3926	this value, the initial vertical profile of the <BR>u-component of
	3927	the geostrophic wind is constructed with <A HREF="#ug_vertical_gradient">ug_vertical_gradient</A>
	3928	and <A HREF="#ug_vertical_gradient_level">ug_vertical_gradient_level</A>.
	3929	The profile constructed in that way is used for creating the
	3930	initial vertical velocity profile of the 3d-model. Either it is
	3931	applied, as it has been specified by the user
	3932	(<A HREF="#initializing_actions">initializing_actions</A> =
	3933	'set_constant_profiles') or it is used for calculating a
	3934	stationary boundary layer wind profile (<A HREF="#initializing_actions">initializing_actions</A>
	3935	= 'set_1d-model_profiles'). If ug is constant with height (i.e.
	3936	ug(k)=<B>ug_surface</B>) and  has a large value, it is
	3937	recommended to use a Galilei-transformation of the coordinate
	3938	system, if possible (see <A HREF="#galilei_transformation">galilei_transformation</A>),
	3939	in order to obtain larger time steps.<BR><BR><B>Attention:</B><BR>In
	3940	case of ocean runs (see <A HREF="#ocean">ocean</A>), this
	3941	parameter gives the geostrophic velocity value (i.e. the pressure
	3942	gradient) at the sea surface, which is at k=nzt. The profile is
	3943	then constructed from the surface down to the bottom of the model.</P>
	3944	</TD>
	3945	</TR>
	3946	<TR>
	3947	<TD WIDTH=126>
	3948	<P><A NAME="ug_vertical_gradient"></A><B>ug_vertical_gradient</B></P>
	3949	</TD>
	3950	<TD WIDTH=45>
	3951	<P>R(10)</P>
	3952	</TD>
	3953	<TD WIDTH=159>
	3954	<P><I>10 * 0.0</I></P>
	3955	</TD>
	3956	<TD WIDTH=1280>
	3957	<P>Gradient(s) of the initial profile of the  u-component of
	3958	the geostrophic wind (in 1/100s).<BR><BR>The gradient holds
	3959	starting from the height level defined by
	3960	<A HREF="#ug_vertical_gradient_level">ug_vertical_gradient_level</A>
	3961	(precisely: for all uv levels k where zu(k) >
	3962	<A HREF="#ug_vertical_gradient_level">ug_vertical_gradient_level</A>,
	3963	ug(k) is set: ug(k) = ug(k-1) + dzu(k) * <B>ug_vertical_gradient</B>)
	3964	up to the top boundary or up to the next height level defined by
	3965	<A HREF="#ug_vertical_gradient_level">ug_vertical_gradient_level</A>.
	3966	A total of 10 different gradients for 11 height intervals (10
	3967	intervals  if <A HREF="#ug_vertical_gradient_level">ug_vertical_gradient_level</A>(1)
	3968	= 0.0) can be assigned. The surface geostrophic wind is assigned
	3969	by <A HREF="#ug_surface">ug_surface</A>.<BR><BR><B>Attention:</B><BR>In
	3970	case of ocean runs (see <A HREF="#ocean">ocean</A>), the profile
	3971	is constructed like described above, but starting from the sea
	3972	surface (k=nzt) down to the bottom boundary of the model. Height
	3973	levels have then to be given as negative values, e.g.
	3974	<B>ug_vertical_gradient_level</B> = <I>-500.0</I>, <I>-1000.0</I>.</P>
	3975	</TD>
	3976	</TR>
	3977	<TR>
	3978	<TD WIDTH=126>
	3979	<P><A NAME="ug_vertical_gradient_level"></A><B>ug_vertical_gradient_level</B></P>
	3980	</TD>
	3981	<TD WIDTH=45>
	3982	<P>R(10)</P>
	3983	</TD>
	3984	<TD WIDTH=159>
	3985	<P><I>10 * 0.0</I></P>
	3986	</TD>
	3987	<TD WIDTH=1280>
	3988	<P>Height level from which on the gradient defined by
	3989	<A HREF="#ug_vertical_gradient">ug_vertical_gradient</A> is
	3990	effective (in m).<BR><BR>The height levels have to be assigned in
	3991	ascending order. For the piecewise construction of a profile of
	3992	the u-component of the geostrophic wind component (ug) see
	3993	<A HREF="#ug_vertical_gradient">ug_vertical_gradient</A>.<BR><BR><B>Attention:</B><BR>In
	3994	case of ocean runs (see <A HREF="#ocean">ocean</A>), the
	3995	(negative) height levels have to be assigned in descending order.</P>
	3996	</TD>
	3997	</TR>
	3998	<TR>
	3999	<TD WIDTH=126>
	4000	<P><A NAME="ups_limit_e"></A><B>ups_limit_e</B></P>
	4001	</TD>
	4002	<TD WIDTH=45>
	4003	<P>R</P>
	4004	</TD>
	4005	<TD WIDTH=159>
	4006	<P><I>0.0</I></P>
	4007	</TD>
	4008	<TD WIDTH=1280>
	4009	<P>Subgrid-scale turbulent kinetic energy difference used as
	4010	criterion for applying the upstream scheme when upstream-spline
	4011	advection is switched on (in m<SUP>2</SUP>/s<SUP>2</SUP>).
	4012	</P>
	4013	<P>This variable steers the appropriate treatment of the advection
	4014	of the subgrid-scale turbulent kinetic energy in case that the
	4015	uptream-spline scheme is used . For further information see
	4016	<A HREF="#ups_limit_pt">ups_limit_pt</A>.
	4017	</P>
	4018	<P>Only positive values are allowed for <B>ups_limit_e</B>.
	4019	</P>
	4020	</TD>
	4021	</TR>
	4022	<TR>
	4023	<TD WIDTH=126>
	4024	<P><A NAME="ups_limit_pt"></A><B>ups_limit_pt</B></P>
	4025	</TD>
	4026	<TD WIDTH=45>
	4027	<P>R</P>
	4028	</TD>
	4029	<TD WIDTH=159>
	4030	<P><I>0.0</I></P>
	4031	</TD>
	4032	<TD WIDTH=1280>
	4033	<P>Temperature difference used as criterion for applying  the
	4034	upstream scheme when upstream-spline advection  is switched
	4035	on (in K).
	4036	</P>
	4037	<P>This criterion is used if the upstream-spline scheme is
	4038	switched on (see <A HREF="#scalar_advec">scalar_advec</A>).<BR>If,
	4039	for a given gridpoint, the absolute temperature difference with
	4040	respect to the upstream grid point is smaller than the value given
	4041	for <B>ups_limit_pt</B>, the upstream scheme is used for this
	4042	gridpoint (by default, the upstream-spline scheme is always used).
	4043	Reason: in case of a very small upstream gradient, the advection
	4044	should cause only a very small tendency. However, in such
	4045	situations the upstream-spline scheme may give wrong tendencies at
	4046	a grid point due to spline overshooting, if simultaneously the
	4047	downstream gradient is very large. In such cases it may be more
	4048	reasonable to use the upstream scheme. The numerical diffusion
	4049	caused by the upstream schme remains small as long as the upstream
	4050	gradients are small.</P>
	4051	<P>The percentage of grid points for which the upstream scheme is
	4052	actually used, can be output as a time series with respect to the
	4053	three directions in space with run parameter (see <A HREF="chapter_4.2.html#dt_dots">dt_dots</A>,
	4054	the timeseries names in the NetCDF file are <I>'splptx'</I>,
	4055	<I>'splpty'</I>, <I>'splptz'</I>). The percentage of gridpoints
	4056	should stay below a certain limit, however, it is not possible to
	4057	give a general limit, since it depends on the respective flow.
	4058	</P>
	4059	<P>Only positive values are permitted for <B>ups_limit_pt</B>.</P>
	4060	<P>A more effective control of the âovershootsâ can be
	4061	achieved with parameter <A HREF="#cut_spline_overshoot">cut_spline_overshoot</A>.
	4062	</P>
	4063	</TD>
	4064	</TR>
	4065	<TR>
	4066	<TD WIDTH=126>
	4067	<P><A NAME="ups_limit_u"></A><B>ups_limit_u</B></P>
	4068	</TD>
	4069	<TD WIDTH=45>
	4070	<P>R</P>
	4071	</TD>
	4072	<TD WIDTH=159>
	4073	<P><I>0.0</I></P>
	4074	</TD>
	4075	<TD WIDTH=1280>
	4076	<P>Velocity difference (u-component) used as criterion for
	4077	applying the upstream scheme when upstream-spline advection is
	4078	switched on (in m/s).
	4079	</P>
	4080	<P>This variable steers the appropriate treatment of the advection
	4081	of the u-velocity-component in case that the upstream-spline
	4082	scheme is used. For further information see <A HREF="#ups_limit_pt">ups_limit_pt</A>.
	4083	</P>
	4084	<P>Only positive values are permitted for <B>ups_limit_u</B>.</P>
	4085	</TD>
	4086	</TR>
	4087	<TR>
	4088	<TD WIDTH=126>
	4089	<P><A NAME="ups_limit_v"></A><B>ups_limit_v</B></P>
	4090	</TD>
	4091	<TD WIDTH=45>
	4092	<P>R</P>
	4093	</TD>
	4094	<TD WIDTH=159>
	4095	<P><I>0.0</I></P>
	4096	</TD>
	4097	<TD WIDTH=1280>
	4098	<P>Velocity difference (v-component) used as criterion for
	4099	applying the upstream scheme when upstream-spline advection is
	4100	switched on (in m/s).
	4101	</P>
	4102	<P>This variable steers the appropriate treatment of the advection
	4103	of the v-velocity-component in case that the upstream-spline
	4104	scheme is used. For further information see <A HREF="#ups_limit_pt">ups_limit_pt</A>.
	4105	</P>
	4106	<P>Only positive values are permitted for <B>ups_limit_v</B>.</P>
	4107	</TD>
	4108	</TR>
	4109	<TR>
	4110	<TD WIDTH=126>
	4111	<P><A NAME="ups_limit_w"></A><B>ups_limit_w</B></P>
	4112	</TD>
	4113	<TD WIDTH=45>
	4114	<P>R</P>
	4115	</TD>
	4116	<TD WIDTH=159>
	4117	<P><I>0.0</I></P>
	4118	</TD>
	4119	<TD WIDTH=1280>
	4120	<P>Velocity difference (w-component) used as criterion for
	4121	applying the upstream scheme when upstream-spline advection is
	4122	switched on (in m/s).
	4123	</P>
	4124	<P>This variable steers the appropriate treatment of the advection
	4125	of the w-velocity-component in case that the upstream-spline
	4126	scheme is used. For further information see <A HREF="#ups_limit_pt">ups_limit_pt</A>.
	4127	</P>
	4128	<P>Only positive values are permitted for <B>ups_limit_w</B>.</P>
	4129	</TD>
	4130	</TR>
	4131	<TR>
	4132	<TD WIDTH=126>
	4133	<P><A NAME="use_surface_fluxes"></A><B>use_surface_fluxes</B></P>
	4134	</TD>
	4135	<TD WIDTH=45>
	4136	<P>L</P>
	4137	</TD>
	4138	<TD WIDTH=159>
	4139	<P><I>.F.</I></P>
	4140	</TD>
	4141	<TD WIDTH=1280>
	4142	<P>Parameter to steer the treatment of the subgrid-scale vertical
	4143	fluxes within the diffusion terms at k=1 (bottom boundary).</P>
	4144	<P>By default, the near-surface subgrid-scale fluxes are
	4145	parameterized (like in the remaining model domain) using the
	4146	gradient approach. If <B>use_surface_fluxes</B> = <I>.TRUE.</I>,
	4147	the user-assigned surface fluxes are used instead (see
	4148	<A HREF="#surface_heatflux">surface_heatflux</A>,
	4149	<A HREF="#surface_waterflux">surface_waterflux</A> and
	4150	<A HREF="#surface_scalarflux">surface_scalarflux</A>) <B>or</B>
	4151	the surface fluxes are calculated via the Prandtl layer relation
	4152	(depends on the bottom boundary conditions, see <A HREF="#bc_pt_b">bc_pt_b</A>,
	4153	<A HREF="#bc_q_b">bc_q_b</A> and <A HREF="#bc_s_b">bc_s_b</A>).</P>
	4154	<P><B>use_surface_fluxes</B> is automatically set <I>.TRUE.</I>,
	4155	if a Prandtl layer is used (see <A HREF="#prandtl_layer">prandtl_layer</A>).
	4156	</P>
	4157	<P>The user may prescribe the surface fluxes at the bottom
	4158	boundary without using a Prandtl layer by setting
	4159	<B>use_surface_fluxes</B> = <I>.T.</I> and <B>prandtl_layer</B> =
	4160	<I>.F.</I>. If , in this case, the momentum flux (u<SUB>*</SUB><SUP>2</SUP>)
	4161	should also be prescribed, the user must assign an appropriate
	4162	value within the user-defined code.</P>
	4163	</TD>
	4164	</TR>
	4165	<TR>
	4166	<TD WIDTH=126>
	4167	<P><A NAME="use_top_fluxes"></A><B>use_top_fluxes</B></P>
	4168	</TD>
	4169	<TD WIDTH=45>
	4170	<P>L</P>
	4171	</TD>
	4172	<TD WIDTH=159>
	4173	<P><I>.F.</I></P>
	4174	</TD>
	4175	<TD WIDTH=1280>
	4176	<P>Parameter to steer the treatment of the subgrid-scale vertical
	4177	fluxes within the diffusion terms at k=nz (top boundary).</P>
	4178	<P>By default, the fluxes at nz are calculated using the gradient
	4179	approach. If <B>use_top_fluxes</B> = <I>.TRUE.</I>, the
	4180	user-assigned top fluxes are used instead (see <A HREF="#top_heatflux">top_heatflux</A>,
	4181	<A HREF="#top_momentumflux_u">top_momentumflux_u</A>,
	4182	<A HREF="#top_momentumflux_v">top_momentumflux_v</A>,
	4183	<A HREF="#top_salinityflux">top_salinityflux</A>).</P>
	4184	<P>Currently, no value for the latent heatflux can be assigned. In
	4185	case of <B>use_top_fluxes</B> = <I>.TRUE.</I>, the latent heat
	4186	flux at the top will be automatically set to zero.</P>
	4187	</TD>
	4188	</TR>
	4189	<TR>
	4190	<TD WIDTH=126>
	4191	<P><A NAME="use_ug_for_galilei_tr"></A><B>use_ug_for_galilei_tr</B></P>
	4192	</TD>
	4193	<TD WIDTH=45>
	4194	<P>L</P>
	4195	</TD>
	4196	<TD WIDTH=159>
	4197	<P><I>.T.</I></P>
	4198	</TD>
	4199	<TD WIDTH=1280>
	4200	<P>Switch to determine the translation velocity in case that a
	4201	Galilean transformation is used.</P>
	4202	<P>In case of a Galilean transformation (see
	4203	<A HREF="#galilei_transformation">galilei_transformation</A>),
	4204	<B>use_ug_for_galilei_tr</B> = <I>.T.</I>  ensures that the
	4205	coordinate system is translated with the geostrophic windspeed.</P>
	4206	<P>Alternatively, with <B>use_ug_for_galilei_tr</B> = <I>.F</I>.,
	4207	the geostrophic wind can be replaced as translation speed by the
	4208	(volume) averaged velocity. However, in this case the user must be
	4209	aware of fast growing gravity waves, so this choice is usually not
	4210	recommended!</P>
	4211	</TD>
	4212	</TR>
	4213	<TR VALIGN=TOP>
	4214	<TD WIDTH=126>
	4215	<P ALIGN=LEFT><A NAME="use_upstream_for_tke"></A><B>use_upstream_for_tke</B></P>
	4216	</TD>
	4217	<TD WIDTH=45>
	4218	<P ALIGN=LEFT>L</P>
	4219	</TD>
	4220	<TD WIDTH=159>
	4221	<P ALIGN=LEFT><I>.F.</I></P>
	4222	</TD>
	4223	<TD WIDTH=1280>
	4224	<P ALIGN=LEFT>Parameter to choose the advection/timestep scheme to
	4225	be used for the subgrid-scale TKE.<BR><BR>By default, the
	4226	advection scheme and the timestep scheme to be used for the
	4227	subgrid-scale TKE are set by the initialization parameters
	4228	<A HREF="#scalar_advec">scalar_advec</A> and <A HREF="#timestep_scheme">timestep_scheme</A>,
	4229	respectively. <B>use_upstream_for_tke</B> = <I>.T.</I> forces the
	4230	Euler-scheme and the upstream-scheme to be used as timestep scheme
	4231	and advection scheme, respectively. By these methods, the strong
	4232	(artificial) near-surface vertical gradients of the subgrid-scale
	4233	TKE are significantly reduced. This is required when subgrid-scale
	4234	velocities are used for advection of particles (see particle
	4235	package parameter <A HREF="chapter_4.2.html#use_sgs_for_particles">use_sgs_for_particles</A>).</P>
	4236	</TD>
	4237	</TR>
	4238	<TR>
	4239	<TD WIDTH=126>
	4240	<P><A NAME="v_bulk"></A><B>v_bulk</B></P>
	4241	</TD>
	4242	<TD WIDTH=45>
	4243	<P>R</P>
	4244	</TD>
	4245	<TD WIDTH=159>
	4246	<P><I>0.0</I></P>
	4247	</TD>
	4248	<TD WIDTH=1280>
	4249	<P>v-component of the predefined bulk velocity (in m/s).<BR><BR>This
	4250	parameter comes into effect if <A HREF="#conserve_volume_flow">conserve_volume_flow</A>
	4251	= <I>.T.</I> and <A HREF="#conserve_volume_flow_mode">conserve_volume_flow_mode</A>
	4252	= <I>'bulk_velocity'</I>.</P>
	4253	</TD>
	4254	</TR>
	4255	<TR>
	4256	<TD WIDTH=126>
	4257	<P><A NAME="vg_surface"></A><B>vg_surface</B></P>
	4258	</TD>
	4259	<TD WIDTH=45>
	4260	<P>R</P>
	4261	</TD>
	4262	<TD WIDTH=159>
	4263	<P><I>0.0</I></P>
	4264	</TD>
	4265	<TD WIDTH=1280>
	4266	<P>v-component of the geostrophic wind at the surface (in
	4267	m/s).<BR><BR>This parameter assigns the value of the v-component
	4268	of the geostrophic wind (vg) at the surface (k=0). Starting from
	4269	this value, the initial vertical profile of the <BR>v-component of
	4270	the geostrophic wind is constructed with <A HREF="#vg_vertical_gradient">vg_vertical_gradient</A>
	4271	and <A HREF="#vg_vertical_gradient_level">vg_vertical_gradient_level</A>.
	4272	The profile constructed in that way is used for creating the
	4273	initial vertical velocity profile of the 3d-model. Either it is
	4274	applied, as it has been specified by the user
	4275	(<A HREF="#initializing_actions">initializing_actions</A> =
	4276	'set_constant_profiles') or it is used for calculating a
	4277	stationary boundary layer wind profile (<A HREF="#initializing_actions">initializing_actions</A>
	4278	= 'set_1d-model_profiles'). If vg is constant with height (i.e.
	4279	vg(k)=<B>vg_surface</B>) and  has a large value, it is
	4280	recommended to use a Galilei-transformation of the coordinate
	4281	system, if possible (see <A HREF="#galilei_transformation">galilei_transformation</A>),
	4282	in order to obtain larger time steps.<BR><BR><B>Attention:</B><BR>In
	4283	case of ocean runs (see <A HREF="#ocean">ocean</A>), this
	4284	parameter gives the geostrophic velocity value (i.e. the pressure
	4285	gradient) at the sea surface, which is at k=nzt. The profile is
	4286	then constructed from the surface down to the bottom of the model.</P>
	4287	</TD>
	4288	</TR>
	4289	<TR>
	4290	<TD WIDTH=126>
	4291	<P><A NAME="vg_vertical_gradient"></A><B>vg_vertical_gradient</B></P>
	4292	</TD>
	4293	<TD WIDTH=45>
	4294	<P>R(10)</P>
	4295	</TD>
	4296	<TD WIDTH=159>
	4297	<P><I>10 * 0.0</I></P>
	4298	</TD>
	4299	<TD WIDTH=1280>
	4300	<P>Gradient(s) of the initial profile of the  v-component of
	4301	the geostrophic wind (in 1/100s).<BR><BR>The gradient holds
	4302	starting from the height level defined by
	4303	<A HREF="#vg_vertical_gradient_level">vg_vertical_gradient_level</A>
	4304	(precisely: for all uv levels k where zu(k) >
	4305	<A HREF="#vg_vertical_gradient_level">vg_vertical_gradient_level</A>,
	4306	vg(k) is set: vg(k) = vg(k-1) + dzu(k) * <B>vg_vertical_gradient</B>)
	4307	up to the top boundary or up to the next height level defined by
	4308	<A HREF="#vg_vertical_gradient_level">vg_vertical_gradient_level</A>.
	4309	A total of 10 different gradients for 11 height intervals (10
	4310	intervals  if <A HREF="#vg_vertical_gradient_level">vg_vertical_gradient_level</A>(1)
	4311	= 0.0) can be assigned. The surface geostrophic wind is assigned
	4312	by <A HREF="#vg_surface">vg_surface</A>.<BR><BR><B>Attention:</B><BR>In
	4313	case of ocean runs (see <A HREF="#ocean">ocean</A>), the profile
	4314	is constructed like described above, but starting from the sea
	4315	surface (k=nzt) down to the bottom boundary of the model. Height
	4316	levels have then to be given as negative values, e.g.
	4317	<B>vg_vertical_gradient_level</B> = <I>-500.0</I>, <I>-1000.0</I>.</P>
	4318	</TD>
	4319	</TR>
	4320	<TR>
	4321	<TD WIDTH=126>
	4322	<P><A NAME="vg_vertical_gradient_level"></A><B>vg_vertical_gradient_level</B></P>
	4323	</TD>
	4324	<TD WIDTH=45>
	4325	<P>R(10)</P>
	4326	</TD>
	4327	<TD WIDTH=159>
	4328	<P><I>10 * 0.0</I></P>
	4329	</TD>
	4330	<TD WIDTH=1280>
	4331	<P>Height level from which on the gradient defined by
	4332	<A HREF="#vg_vertical_gradient">vg_vertical_gradient</A> is
	4333	effective (in m).<BR><BR>The height levels have to be assigned in
	4334	ascending order. For the piecewise construction of a profile of
	4335	the v-component of the geostrophic wind component (vg) see
	4336	<A HREF="#vg_vertical_gradient">vg_vertical_gradient</A>.<BR><BR><B>Attention:</B><BR>In
	4337	case of ocean runs (see <A HREF="#ocean">ocean</A>), the
	4338	(negative) height levels have to be assigned in descending order.</P>
	4339	</TD>
	4340	</TR>
	4341	<TR>
	4342	<TD WIDTH=126>
	4343	<P><A NAME="wall_adjustment"></A><B>wall_adjustment</B></P>
	4344	</TD>
	4345	<TD WIDTH=45>
	4346	<P>L</P>
	4347	</TD>
	4348	<TD WIDTH=159>
	4349	<P><I>.T.</I></P>
	4350	</TD>
	4351	<TD WIDTH=1280>
	4352	<P>Parameter to restrict the mixing length in the vicinity of the
	4353	bottom boundary (and near vertical walls of a non-flat
	4354	<A HREF="#topography">topography</A>).
	4355	</P>
	4356	<P>With <B>wall_adjustment</B> = <I>.TRUE., </I>the mixing length
	4357	is limited to a maximum of  1.8 * z. This condition typically
	4358	affects only the first grid points above the bottom boundary.</P>
	4359	<P>In case of  a non-flat <A HREF="#topography">topography</A>
	4360	the respective horizontal distance from vertical walls is used.</P>
	4361	</TD>
	4362	</TR>
	4363	<TR>
	4364	<TD WIDTH=126>
	4365	<P><A NAME="wall_heatflux"></A><B>wall_heatflux</B></P>
	4366	</TD>
	4367	<TD WIDTH=45>
	4368	<P>R(5)</P>
	4369	</TD>
	4370	<TD WIDTH=159>
	4371	<P><I>5 * 0.0</I></P>
	4372	</TD>
	4373	<TD WIDTH=1280>
	4374	<P>Prescribed kinematic sensible heat flux in K m/s at the five
	4375	topography faces:</P>
	4376	<P STYLE="margin-left: 0.42in; margin-bottom: 0in"><B>wall_heatflux(0)
	4377	</B>top face<BR><B>wall_heatflux(1)    </B>left
	4378	face<BR><B>wall_heatflux(2)    </B>right
	4379	face<BR><B>wall_heatflux(3)    </B>south
	4380	face<BR><B>wall_heatflux(4)    </B>north face</P>
	4381	<P STYLE="margin-bottom: 0in"><BR>This parameter applies only in
	4382	case of a non-flat <A HREF="#topography">topography</A>. The
	4383	parameter <A HREF="#random_heatflux">random_heatflux</A> can be
	4384	used to impose random perturbations on the internal
	4385	two-dimensional surface heat flux field <I>shf</I> that is
	4386	composed of <A HREF="#surface_heatflux">surface_heatflux</A> at
	4387	the bottom surface and <B>wall_heatflux(0)</B> at the topography
	4388	top face. </P>
	4389	</TD>
	4390	</TR>
	4391	</TABLE>
	4392	<P><BR><BR>
	4393	</P>
	4394	<P STYLE="line-height: 100%"><BR><FONT COLOR="#000080"><A HREF="chapter_4.0.html"><FONT COLOR="#000080"><IMG SRC="left.gif" NAME="Grafik1" ALIGN=BOTTOM WIDTH=32 HEIGHT=32 BORDER=1></FONT></A><A HREF="index.html"><FONT COLOR="#000080"><IMG SRC="up.gif" NAME="Grafik2" ALIGN=BOTTOM WIDTH=32 HEIGHT=32 BORDER=1></FONT></A><A HREF="chapter_4.2.html"><FONT COLOR="#000080"><IMG SRC="right.gif" NAME="Grafik3" ALIGN=BOTTOM WIDTH=32 HEIGHT=32 BORDER=1></FONT></A></FONT></P>
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	4396	chapter_4.1.html 328 2009-05-28 12:13:56Z letzel $
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