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further preliminary changes concerning coupling
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[5]	1	<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
	2	<html><head>
[62]	3	<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"><title>PALM chapter 4.1</title></head>
[61]	4	<body><h3><a name="chapter4.1"></a>4.1
	5	Initialization parameters</h3>
	6	<br><table style="text-align: left; width: 100%;" border="1" cellpadding="2" cellspacing="2"> <tbody>
	7	<tr> <td style="vertical-align: top;"><font size="4"><b>Parameter name</b></font></td>
	8	<td style="vertical-align: top;"><font size="4"><b>Type</b></font></td>
	9	<td style="vertical-align: top;"> <p><b><font size="4">Default</font></b> <br> <b><font size="4">value</font></b></p> </td>
	10	<td style="vertical-align: top;"><font size="4"><b>Explanation</b></font></td>
	11	</tr> <tr> <td style="vertical-align: top;">
	12	<p><a name="adjust_mixing_length"></a><b>adjust_mixing_length</b></p>
	13	</td> <td style="vertical-align: top;">L</td>
	14	<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p style="font-style: normal;">Near-surface adjustment of the
	15	mixing length to the Prandtl-layer law.  </p> <p>Usually
	16	the mixing length in LES models l<sub>LES</sub>
[5]	17	depends (as in PALM) on the grid size and is possibly restricted
	18	further in case of stable stratification and near the lower wall (see
	19	parameter <a href="#wall_adjustment">wall_adjustment</a>).
	20	With <b>adjust_mixing_length</b> = <span style="font-style: italic;">.T.</span>
[61]	21	the Prandtl' mixing length l<sub>PR</sub> = kappa * z/phi
	22	is calculated
[5]	23	and the mixing length actually used in the model is set l = MIN (l<sub>LES</sub>,
[61]	24	l<sub>PR</sub>). This usually gives a decrease of the
	25	mixing length at
[5]	26	the bottom boundary and considers the fact that eddy sizes
[61]	27	decrease in the vicinity of the wall.  </p> <p style="font-style: normal;"><b>Warning:</b> So
	28	far, there is
[5]	29	no good experience with <b>adjust_mixing_length</b> = <span style="font-style: italic;">.T.</span> !  </p>
[61]	30	<p>With <b>adjust_mixing_length</b> = <span style="font-style: italic;">.T.</span> and the
	31	Prandtl-layer being
	32	switched on (see <a href="#prandtl_layer">prandtl_layer</a>)
	33	<span style="font-style: italic;">'(u)* 2+neumann'</span>
[5]	34	should always be set as the lower boundary condition for the TKE (see <a href="#bc_e_b">bc_e_b</a>),
	35	otherwise the near-surface value of the TKE is not in agreement with
	36	the Prandtl-layer law (Prandtl-layer law and Prandtl-Kolmogorov-Ansatz
[61]	37	should provide the same value for K<sub>m</sub>). A warning
	38	is given,
	39	if this is not the case.</p> </td> </tr> <tr>
	40	<td style="vertical-align: top;"> <p><a name="alpha_surface"></a><b>alpha_surface</b></p>
	41	</td> <td style="vertical-align: top;">R<br> </td>
	42	<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
	43	<td style="vertical-align: top;"> <p style="font-style: normal;">Inclination of the model domain
	44	with respect to the horizontal (in degrees).  </p> <p style="font-style: normal;">By means of <b>alpha_surface</b>
[5]	45	the model domain can be inclined in x-direction with respect to the
	46	horizontal. In this way flows over inclined surfaces (e.g. drainage
[61]	47	flows, gravity flows) can be simulated. In case of <b>alpha_surface
	48	</b>/= <span style="font-style: italic;">0</span>
	49	the buoyancy term
[5]	50	appears both in
	51	the equation of motion of the u-component and of the w-component.<br>
[61]	52	</p> <p style="font-style: normal;">An inclination
	53	is only possible in
[5]	54	case of cyclic horizontal boundary conditions along x AND y (see <a href="#bc_lr">bc_lr</a>
	55	and <a href="#bc_ns">bc_ns</a>) and <a href="#topography">topography</a> = <span style="font-style: italic;">'flat'</span>. </p>
[61]	56	<p>Runs with inclined surface still require additional
[5]	57	user-defined code as well as modifications to the default code. Please
	58	ask the <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/PALM_group.html#0">PALM
[61]	59	developer  group</a>.</p> </td> </tr>
	60	<tr> <td style="vertical-align: top;"> <p><a name="bc_e_b"></a><b>bc_e_b</b></p> </td>
	61	<td style="vertical-align: top;">C * 20</td> <td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
	62	<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
	63	TKE.  </p> <p><b>bc_e_b</b> may be
	64	set to <span style="font-style: italic;">'neumann'</span>
	65	or <span style="font-style: italic;">'(u) * 2+neumann'</span>.
	66	<b>bc_e_b</b>
	67	= <span style="font-style: italic;">'neumann'</span>
	68	yields to
[5]	69	e(k=0)=e(k=1) (Neumann boundary condition), where e(k=1) is calculated
[61]	70	via the prognostic TKE equation. Choice of <span style="font-style: italic;">'(u)*2+neumann'</span>
	71	also yields to
[5]	72	e(k=0)=e(k=1), but the TKE at the Prandtl-layer top (k=1) is calculated
	73	diagnostically by e(k=1)=(us/0.1)**2. However, this is only allowed if
	74	a Prandtl-layer is used (<a href="#prandtl_layer">prandtl_layer</a>).
[61]	75	If this is not the case, a warning is given and <b>bc_e_b</b>
	76	is reset
	77	to <span style="font-style: italic;">'neumann'</span>.
	78	</p> <p style="font-style: normal;">At the top
	79	boundary a Neumann
	80	boundary condition is generally used: (e(nz+1) = e(nz)).</p> </td>
	81	</tr> <tr> <td style="vertical-align: top;">
	82	<p><a name="bc_lr"></a><b>bc_lr</b></p>
	83	</td> <td style="vertical-align: top;">C * 20</td>
	84	<td style="vertical-align: top;"><span style="font-style: italic;">'cyclic'</span></td>
	85	<td style="vertical-align: top;">Boundary
	86	condition along x (for all quantities).<br> <br>
	87	By default, a cyclic boundary condition is used along x.<br> <br>
	88	<span style="font-weight: bold;">bc_lr</span> may
	89	also be
[75]	90	assigned the values <span style="font-style: italic;">'dirichlet/radiation'</span>
	91	(inflow from left, outflow to the right) or <span style="font-style: italic;">'radiation/dirichlet'</span>
[61]	92	(inflow from
[5]	93	right, outflow to the left). This requires the multi-grid method to be
	94	used for solving the Poisson equation for perturbation pressure (see <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">psolver</a>)
[75]	95	and it also requires cyclic boundary conditions along y (see <a href="#bc_ns">bc_ns</a>).<br> <br>
[5]	96	In case of these non-cyclic lateral boundaries, a Dirichlet condition
	97	is used at the inflow for all quantities (initial vertical profiles -
	98	see <a href="#initializing_actions">initializing_actions</a>
	99	- are fixed during the run) except u, to which a Neumann (zero
[75]	100	gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components, while a Neumann (zero
	101	gradient) condition is used for the scalars. For perturbation
[5]	102	pressure Neumann (zero gradient) conditions are assumed both at the
[61]	103	inflow and at the outflow.<br> <br>
[5]	104	When using non-cyclic lateral boundaries, a filter is applied to the
	105	velocity field in the vicinity of the outflow in order to suppress any
	106	reflections of outgoing disturbances (see <a href="#km_damp_max">km_damp_max</a>
	107	and <a href="#outflow_damping_width">outflow_damping_width</a>).<br>
[61]	108	<br>
[5]	109	In order to maintain a turbulent state of the flow, it may be
	110	neccessary to continuously impose perturbations on the horizontal
	111	velocity field in the vicinity of the inflow throughout the whole run.
	112	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>.
	113	The horizontal range to which these perturbations are applied is
	114	controlled by the parameters <a href="#inflow_disturbance_begin">inflow_disturbance_begin</a>
	115	and <a href="#inflow_disturbance_end">inflow_disturbance_end</a>.
	116	The vertical range and the perturbation amplitude are given by <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_level_b</a>,
[61]	117	<a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_level_t</a>,
[5]	118	and <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_amplitude</a>.
	119	The time interval at which perturbations are to be imposed is set by <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#dt_disturb">dt_disturb</a>.<br>
[61]	120	<br>
[5]	121	In 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
[61]	122	at_all_substeps</a> = .T. should be used.<br> <br> <span style="font-weight: bold;">Note:</span><br>
[5]	123	Using non-cyclic lateral boundaries requires very sensitive adjustments
	124	of the inflow (vertical profiles) and the bottom boundary conditions,
	125	e.g. a surface heating should not be applied near the inflow boundary
	126	because this may significantly disturb the inflow. Please check the
[61]	127	model results very carefully.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_ns"></a><b>bc_ns</b></p>
	128	</td> <td style="vertical-align: top;">C * 20</td>
	129	<td style="vertical-align: top;"><span style="font-style: italic;">'cyclic'</span></td>
	130	<td style="vertical-align: top;">Boundary
	131	condition along y (for all quantities).<br> <br>
	132	By default, a cyclic boundary condition is used along y.<br> <br>
	133	<span style="font-weight: bold;">bc_ns</span> may
	134	also be
[75]	135	assigned the values <span style="font-style: italic;">'dirichlet/radiation'</span>
	136	(inflow from rear ("north"), outflow to the front ("south")) or <span style="font-style: italic;">'radiation/dirichlet'</span>
[5]	137	(inflow from front ("south"), outflow to the rear ("north")). This
	138	requires the multi-grid
	139	method to be used for solving the Poisson equation for perturbation
	140	pressure (see <a href="chapter_4.2.html#psolver">psolver</a>)
[61]	141	and it also requires cyclic boundary conditions along x (see<br> <a href="#bc_lr">bc_lr</a>).<br> <br>
[5]	142	In case of these non-cyclic lateral boundaries, a Dirichlet condition
	143	is used at the inflow for all quantities (initial vertical profiles -
[75]	144	see <a href="chapter_4.1.html#initializing_actions">initializing_actions</a>
	145	- are fixed during the run) except u, to which a Neumann (zero
	146	gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components, while a Neumann (zero
	147	gradient) condition is used for the scalars. For perturbation
[5]	148	pressure Neumann (zero gradient) conditions are assumed both at the
[61]	149	inflow and at the outflow.<br> <br>
[5]	150	For further details regarding non-cyclic lateral boundary conditions
[61]	151	see <a href="#bc_lr">bc_lr</a>.</td> </tr>
	152	<tr> <td style="vertical-align: top;"> <p><a name="bc_p_b"></a><b>bc_p_b</b></p> </td>
	153	<td style="vertical-align: top;">C * 20</td> <td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
	154	<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
	155	perturbation pressure.  </p> <p>Allowed values
	156	are <span style="font-style: italic;">'dirichlet'</span>,
	157	<span style="font-style: italic;">'neumann'</span>
	158	and <span style="font-style: italic;">'neumann+inhomo'</span>.
	159	<span style="font-style: italic;">'dirichlet'</span>
	160	sets
[5]	161	p(k=0)=0.0,  <span style="font-style: italic;">'neumann'</span>
	162	sets p(k=0)=p(k=1). <span style="font-style: italic;">'neumann+inhomo'</span>
	163	corresponds to an extended Neumann boundary condition where heat flux
	164	or temperature inhomogeneities near the
[61]	165	surface (pt(k=1))  are additionally regarded (see Shen and
	166	LeClerc
[5]	167	(1995, Q.J.R. Meteorol. Soc.,
	168	1209)). This condition is only permitted with the Prandtl-layer
	169	switched on (<a href="#prandtl_layer">prandtl_layer</a>),
[61]	170	otherwise the run is terminated.  </p> <p>Since
	171	at the bottom boundary of the model the vertical
[5]	172	velocity
[61]	173	disappears (w(k=0) = 0.0), the consistent Neumann condition (<span style="font-style: italic;">'neumann'</span> or <span style="font-style: italic;">'neumann+inhomo'</span>)
	174	dp/dz = 0 should
[5]	175	be used, which leaves the vertical component w unchanged when the
	176	pressure solver is applied. Simultaneous use of the Neumann boundary
	177	conditions both at the bottom and at the top boundary (<a href="#bc_p_t">bc_p_t</a>)
	178	usually yields no consistent solution for the perturbation pressure and
[61]	179	should be avoided.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_p_t"></a><b>bc_p_t</b></p>
	180	</td> <td style="vertical-align: top;">C * 20</td>
	181	<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
	182	<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
	183	perturbation pressure.  </p> <p style="font-style: normal;">Allowed values are <span style="font-style: italic;">'dirichlet'</span>
	184	(p(k=nz+1)= 0.0) or <span style="font-style: italic;">'neumann'</span>
	185	(p(k=nz+1)=p(k=nz)).  </p> <p>Simultaneous use
	186	of Neumann boundary conditions both at the
[5]	187	top and bottom boundary (<a href="#bc_p_b">bc_p_b</a>)
	188	usually yields no consistent solution for the perturbation pressure and
	189	should be avoided. Since at the bottom boundary the Neumann
	190	condition  is a good choice (see <a href="#bc_p_b">bc_p_b</a>),
[61]	191	a Dirichlet condition should be set at the top boundary.</p> </td>
	192	</tr> <tr> <td style="vertical-align: top;">
	193	<p><a name="bc_pt_b"></a><b>bc_pt_b</b></p>
	194	</td> <td style="vertical-align: top;">C*20</td>
	195	<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
	196	<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
	197	potential temperature.  </p> <p>Allowed values
	198	are <span style="font-style: italic;">'dirichlet'</span>
[5]	199	(pt(k=0) = const. = <a href="#pt_surface">pt_surface</a>
	200	+ <a href="#pt_surface_initial_change">pt_surface_initial_change</a>;
	201	the user may change this value during the run using user-defined code)
	202	and <span style="font-style: italic;">'neumann'</span>
	203	(pt(k=0)=pt(k=1)).  <br>
[61]	204	When a constant surface sensible heat flux is used (<a href="#surface_heatflux">surface_heatflux</a>), <b>bc_pt_b</b>
	205	= <span style="font-style: italic;">'neumann'</span>
[5]	206	must be used, because otherwise the resolved scale may contribute to
	207	the surface flux so that a constant value cannot be guaranteed.</p>
[61]	208	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pc_pt_t"></a><b>bc_pt_t</b></p>
	209	</td> <td style="vertical-align: top;">C * 20</td>
[97]	210	<td style="vertical-align: top;"><span style="font-style: italic;">'initial_ gradient'</span></td>
[61]	211	<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
	212	potential temperature.  </p> <p>Allowed are the
	213	values <span style="font-style: italic;">'dirichlet' </span>(pt(k=nz+1)
	214	does not change during the run), <span style="font-style: italic;">'neumann'</span>
	215	(pt(k=nz+1)=pt(k=nz)), and <span style="font-style: italic;">'initial_gradient'</span>.
	216	With the 'initial_gradient'-condition the value of the temperature
	217	gradient at the top is
[5]	218	calculated from the initial
[61]	219	temperature profile (see <a href="#pt_surface">pt_surface</a>,
	220	<a href="#pt_vertical_gradient">pt_vertical_gradient</a>)
[40]	221	by bc_pt_t_val = (pt_init(k=nz+1) -
	222	pt_init(k=nz)) / dzu(nz+1).<br>
[5]	223	Using this value (assumed constant during the
	224	run) the temperature boundary values are calculated as  </p>
[61]	225	<ul> <p style="font-style: normal;">pt(k=nz+1) =
	226	pt(k=nz) +
	227	bc_pt_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up to k=nz the prognostic
[40]	228	equation for the temperature is solved).<br>
[61]	229	When a constant sensible heat flux is used at the top boundary (<a href="chapter_4.1.html#top_heatflux">top_heatflux</a>),
	230	<b>bc_pt_t</b> = <span style="font-style: italic;">'neumann'</span>
[40]	231	must be used, because otherwise the resolved scale may contribute to
[61]	232	the top flux so that a constant value cannot be guaranteed.</p> </td>
	233	</tr> <tr> <td style="vertical-align: top;">
	234	<p><a name="bc_q_b"></a><b>bc_q_b</b></p>
	235	</td> <td style="vertical-align: top;">C * 20</td>
	236	<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
	237	<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
	238	specific humidity / total water content.  </p> <p>Allowed
	239	values are <span style="font-style: italic;">'dirichlet'</span>
[5]	240	(q(k=0) = const. = <a href="#q_surface">q_surface</a>
	241	+ <a href="#q_surface_initial_change">q_surface_initial_change</a>;
	242	the user may change this value during the run using user-defined code)
	243	and <span style="font-style: italic;">'neumann'</span>
	244	(q(k=0)=q(k=1)).  <br>
[61]	245	When a constant surface latent heat flux is used (<a href="#surface_waterflux">surface_waterflux</a>), <b>bc_q_b</b>
	246	= <span style="font-style: italic;">'neumann'</span>
[5]	247	must be used, because otherwise the resolved scale may contribute to
	248	the surface flux so that a constant value cannot be guaranteed.</p>
[61]	249	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_q_t"></a><b>bc_q_t</b></p>
	250	</td> <td style="vertical-align: top;"><span style="font-style: italic;">C
	251	* 20</span></td> <td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
	252	<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
	253	specific humidity / total water content.  </p> <p>Allowed
	254	are the values <span style="font-style: italic;">'dirichlet'</span>
[5]	255	(q(k=nz) and q(k=nz+1) do
	256	not change during the run) and <span style="font-style: italic;">'neumann'</span>.
	257	With the Neumann boundary
	258	condition the value of the humidity gradient at the top is calculated
	259	from the
[61]	260	initial humidity profile (see <a href="#q_surface">q_surface</a>,
	261	<a href="#q_vertical_gradient">q_vertical_gradient</a>)
[5]	262	by: bc_q_t_val = ( q_init(k=nz) - q_init(k=nz-1)) / dzu(nz).<br>
	263	Using this value (assumed constant during the run) the humidity
	264	boundary values
[61]	265	are calculated as  </p> <ul> <p style="font-style: normal;">q(k=nz+1) =q(k=nz) +
	266	bc_q_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up tp k=nz the prognostic
	267	equation for q is solved). </p> </td> </tr> <tr>
	268	<td style="vertical-align: top;"> <p><a name="bc_s_b"></a><b>bc_s_b</b></p> </td>
	269	<td style="vertical-align: top;">C * 20</td> <td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
	270	<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
	271	scalar concentration.  </p> <p>Allowed values
	272	are <span style="font-style: italic;">'dirichlet'</span>
[5]	273	(s(k=0) = const. = <a href="#s_surface">s_surface</a>
	274	+ <a href="#s_surface_initial_change">s_surface_initial_change</a>;
	275	the user may change this value during the run using user-defined code)
[61]	276	and <span style="font-style: italic;">'neumann'</span>
	277	(s(k=0) =
[5]	278	s(k=1)).  <br>
[61]	279	When a constant surface concentration flux is used (<a href="#surface_scalarflux">surface_scalarflux</a>), <b>bc_s_b</b>
	280	= <span style="font-style: italic;">'neumann'</span>
[5]	281	must be used, because otherwise the resolved scale may contribute to
	282	the surface flux so that a constant value cannot be guaranteed.</p>
[61]	283	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_s_t"></a><b>bc_s_t</b></p>
	284	</td> <td style="vertical-align: top;">C * 20</td>
	285	<td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
	286	<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
	287	scalar concentration.  </p> <p>Allowed are the
	288	values <span style="font-style: italic;">'dirichlet'</span>
[5]	289	(s(k=nz) and s(k=nz+1) do
	290	not change during the run) and <span style="font-style: italic;">'neumann'</span>.
	291	With the Neumann boundary
	292	condition the value of the scalar concentration gradient at the top is
	293	calculated
[61]	294	from the initial scalar concentration profile (see <a href="#s_surface">s_surface</a>, <a href="#s_vertical_gradient">s_vertical_gradient</a>)
[5]	295	by: bc_s_t_val = (s_init(k=nz) - s_init(k=nz-1)) / dzu(nz).<br>
	296	Using this value (assumed constant during the run) the concentration
	297	boundary values
[61]	298	are calculated as </p> <ul> <p style="font-style: normal;">s(k=nz+1) = s(k=nz) +
	299	bc_s_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up to k=nz the prognostic
[5]	300	equation for the scalar concentration is
[97]	301	solved).</p> </td> </tr> <tr><td style="vertical-align: top;"><a name="bc_sa_t"></a><span style="font-weight: bold;">bc_sa_t</span></td><td style="vertical-align: top;">C * 20</td><td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td><td style="vertical-align: top;"><p style="font-style: normal;">Top boundary condition of the salinity.  </p> <p>This parameter only comes into effect for ocean runs (see parameter <a href="#ocean">ocean</a>).</p><p style="font-style: normal;">Allowed are the
	302	values <span style="font-style: italic;">'dirichlet' </span>(sa(k=nz+1)
	303	does not change during the run) and <span style="font-style: italic;">'neumann'</span>
	304	(sa(k=nz+1)=sa(k=nz))<span style="font-style: italic;"></span>. <br><br>
	305	When a constant salinity flux is used at the top boundary (<a href="chapter_4.1.html#top_salinityflux">top_salinityflux</a>),
	306	<b>bc_sa_t</b> = <span style="font-style: italic;">'neumann'</span>
	307	must be used, because otherwise the resolved scale may contribute to
	308	the top flux so that a constant value cannot be guaranteed.</p></td></tr><tr> <td style="vertical-align: top;"> <p><a name="bc_uv_b"></a><b>bc_uv_b</b></p>
[61]	309	</td> <td style="vertical-align: top;">C * 20</td>
	310	<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
	311	<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
	312	horizontal velocity components u and v.  </p> <p>Allowed
	313	values are <span style="font-style: italic;">'dirichlet' </span>and
	314	<span style="font-style: italic;">'neumann'</span>. <b>bc_uv_b</b>
	315	= <span style="font-style: italic;">'dirichlet'</span>
	316	yields the
[5]	317	no-slip condition with u=v=0 at the bottom. Due to the staggered grid
	318	u(k=0) and v(k=0) are located at z = - 0,5 * <a href="#dz">dz</a>
	319	(below the bottom), while u(k=1) and v(k=1) are located at z = +0,5 *
	320	dz. u=v=0 at the bottom is guaranteed using mirror boundary
[61]	321	condition:  </p> <ul> <p style="font-style: normal;">u(k=0) = - u(k=1) and v(k=0) = -
	322	v(k=1)</p> </ul> <p style="font-style: normal;">The
	323	Neumann boundary condition
[5]	324	yields the free-slip condition with u(k=0) = u(k=1) and v(k=0) =
	325	v(k=1).
	326	With Prandtl - layer switched on, the free-slip condition is not
	327	allowed (otherwise the run will be terminated)<font color="#000000">.</font></p>
[61]	328	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_uv_t"></a><b>bc_uv_t</b></p>
	329	</td> <td style="vertical-align: top;">C * 20</td>
	330	<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
	331	<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
	332	horizontal velocity components u and v.  </p> <p>Allowed
	333	values are <span style="font-style: italic;">'dirichlet'</span>
	334	and <span style="font-style: italic;">'neumann'</span>.
	335	The
[5]	336	Dirichlet condition yields u(k=nz+1) = ug(nz+1) and v(k=nz+1) =
	337	vg(nz+1),
	338	Neumann condition yields the free-slip condition with u(k=nz+1) =
	339	u(k=nz) and v(k=nz+1) = v(k=nz) (up to k=nz the prognostic equations
[97]	340	for the velocities are solved).</p> </td> </tr> <tr><td style="vertical-align: top;"><a name="bottom_salinityflux"></a><span style="font-weight: bold;">bottom_salinityflux</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">0.0</span></td><td style="vertical-align: top;"><p>Kinematic salinity flux near the surface (in psu m/s). </p>This parameter only comes into effect for ocean runs (see parameter <a href="chapter_4.1.html#ocean">ocean</a>).<p>The
	341	respective salinity flux value is used
	342	as bottom (horizontally homogeneous) boundary condition for the salinity equation. This additionally requires that a Neumann
	343	condition must be used for the salinity, which is currently the only available condition.<br> </p> </td></tr><tr>
[61]	344	<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_height"></a>building_height</span></td>
	345	<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">50.0</span></td> <td>Height
	346	of a single building in m.<br> <br> <span style="font-weight: bold;">building_height</span> must
	347	be less than the height of the model domain. This parameter requires
	348	the use of <a href="#topography">topography</a>
	349	= <span style="font-style: italic;">'single_building'</span>.</td>
	350	</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_length_x"></a>building_length_x</span></td>
	351	<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">50.0</span></td> <td><span style="font-style: italic;"></span>Width of a single
	352	building in m.<br> <br>
	353	Currently, <span style="font-weight: bold;">building_length_x</span>
	354	must be at least <span style="font-style: italic;">3
	355	* </span><a style="font-style: italic;" href="#dx">dx</a> and no more than <span style="font-style: italic;">( </span><a style="font-style: italic;" href="#nx">nx</a><span style="font-style: italic;"> - 1 ) </span><span style="font-style: italic;"> * <a href="#dx">dx</a>
	356	</span><span style="font-style: italic;">- <a href="#building_wall_left">building_wall_left</a></span>.
	357	This parameter requires the use of <a href="#topography">topography</a>
	358	= <span style="font-style: italic;">'single_building'</span>.</td>
	359	</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_length_y"></a>building_length_y</span></td>
	360	<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">50.0</span></td> <td>Depth
	361	of a single building in m.<br> <br>
	362	Currently, <span style="font-weight: bold;">building_length_y</span>
	363	must be at least <span style="font-style: italic;">3
	364	* </span><a style="font-style: italic;" href="#dy">dy</a> and no more than <span style="font-style: italic;">( </span><a style="font-style: italic;" href="#ny">ny</a><span style="font-style: italic;"> - 1 ) </span><span style="font-style: italic;"> * <a href="#dy">dy</a></span><span style="font-style: italic;"> - <a href="#building_wall_south">building_wall_south</a></span>. This parameter requires
	365	the use of <a href="#topography">topography</a>
	366	= <span style="font-style: italic;">'single_building'</span>.</td>
	367	</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_wall_left"></a>building_wall_left</span></td>
	368	<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">building centered in x-direction</span></td>
	369	<td>x-coordinate of the left building wall (distance between the
	370	left building wall and the left border of the model domain) in m.<br>
	371	<br>
	372	Currently, <span style="font-weight: bold;">building_wall_left</span>
	373	must be at least <span style="font-style: italic;">1
	374	* </span><a style="font-style: italic;" href="#dx">dx</a> and less than <span style="font-style: italic;">( <a href="#nx">nx</a>
	375	- 1 ) * <a href="#dx">dx</a> -  <a href="#building_length_x">building_length_x</a></span>.
	376	This parameter requires the use of <a href="#topography">topography</a>
	377	= <span style="font-style: italic;">'single_building'</span>.<br>
	378	<br>
	379	The default value <span style="font-weight: bold;">building_wall_left</span>
	380	= <span style="font-style: italic;">( ( <a href="#nx">nx</a> +
	381	1 ) * <a href="#dx">dx</a> -  <a href="#building_length_x">building_length_x</a> ) / 2</span>
	382	centers the building in x-direction. </td> </tr> <tr>
	383	<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_wall_south"></a>building_wall_south</span></td>
	384	<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;"></span><span style="font-style: italic;">building centered in y-direction</span></td>
	385	<td>y-coordinate of the South building wall (distance between the
[5]	386	South building wall and the South border of the model domain) in m.<br>
[61]	387	<br>
	388	Currently, <span style="font-weight: bold;">building_wall_south</span>
	389	must be at least <span style="font-style: italic;">1
	390	* </span><a style="font-style: italic;" href="#dy">dy</a> and less than <span style="font-style: italic;">( <a href="#ny">ny</a>
	391	- 1 ) * <a href="#dy">dy</a> -  <a href="#building_length_y">building_length_y</a></span>.
	392	This parameter requires the use of <a href="#topography">topography</a>
	393	= <span style="font-style: italic;">'single_building'</span>.<br>
	394	<br>
	395	The default value <span style="font-weight: bold;">building_wall_south</span>
	396	= <span style="font-style: italic;">( ( <a href="#ny">ny</a> +
	397	1 ) * <a href="#dy">dy</a> -  <a href="#building_length_y">building_length_y</a> ) / 2</span>
	398	centers the building in y-direction. </td> </tr> <tr>
	399	<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="cloud_droplets"></a>cloud_droplets</span><br>
	400	</td> <td style="vertical-align: top;">L<br> </td>
	401	<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span><br> </td>
	402	<td style="vertical-align: top;">Parameter to switch on
	403	usage of cloud droplets.<br> <br>
[5]	404	Cloud droplets require to use the particle package (<span style="font-weight: bold;">mrun</span>-option <span style="font-family: monospace;">-p particles</span>),
	405	so in this case a particle corresponds to a droplet. The droplet
	406	features (number of droplets, initial radius, etc.) can be steered with
	407	the  respective particle parameters (see e.g. <a href="#chapter_4.2.html#radius">radius</a>).
	408	The real number of initial droplets in a grid cell is equal to the
	409	initial number of droplets (defined by the particle source parameters <span lang="en-GB"><font face="Thorndale, serif"> </font></span><a href="chapter_4.2.html#pst"><span lang="en-GB"><font face="Thorndale, serif">pst</font></span></a><span lang="en-GB"><font face="Thorndale, serif">, </font></span><a href="chapter_4.2.html#psl"><span lang="en-GB"><font face="Thorndale, serif">psl</font></span></a><span lang="en-GB"><font face="Thorndale, serif">, </font></span><a href="chapter_4.2.html#psr"><span lang="en-GB"><font face="Thorndale, serif">psr</font></span></a><span lang="en-GB"><font face="Thorndale, serif">, </font></span><a href="chapter_4.2.html#pss"><span lang="en-GB"><font face="Thorndale, serif">pss</font></span></a><span lang="en-GB"><font face="Thorndale, serif">, </font></span><a href="chapter_4.2.html#psn"><span lang="en-GB"><font face="Thorndale, serif">psn</font></span></a><span lang="en-GB"><font face="Thorndale, serif">, </font></span><a href="chapter_4.2.html#psb"><span lang="en-GB"><font face="Thorndale, serif">psb</font></span></a><span lang="en-GB"><font face="Thorndale, serif">, </font></span><a href="chapter_4.2.html#pdx"><span lang="en-GB"><font face="Thorndale, serif">pdx</font></span></a><span lang="en-GB"><font face="Thorndale, serif">, </font></span><a href="chapter_4.2.html#pdy"><span lang="en-GB"><font face="Thorndale, serif">pdy</font></span></a>
[61]	410	<span lang="en-GB"><font face="Thorndale, serif">and
	411	</font></span><a href="chapter_4.2.html#pdz"><span lang="en-GB"><font face="Thorndale, serif">pdz</font></span></a><span lang="en-GB"></span><span lang="en-GB"></span>)
	412	times the <a href="#initial_weighting_factor">initial_weighting_factor</a>.<br>
	413	<br>
	414	In case of using cloud droplets, the default condensation scheme in
	415	PALM cannot be used, i.e. <a href="#cloud_physics">cloud_physics</a>
	416	must be set <span style="font-style: italic;">.F.</span>.<br>
	417	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="cloud_physics"></a><b>cloud_physics</b></p>
	418	</td> <td style="vertical-align: top;">L<br> </td>
	419	<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p>Parameter to switch
	420	on the condensation scheme.  </p>
	421	For <b>cloud_physics =</b> <span style="font-style: italic;">.TRUE.</span>, equations
	422	for the
[5]	423	liquid water
	424	content and the liquid water potential temperature are solved instead
	425	of those for specific humidity and potential temperature. Note
	426	that a grid volume is assumed to be either completely saturated or
	427	completely
	428	unsaturated (0%-or-100%-scheme). A simple precipitation scheme can
	429	additionally be switched on with parameter <a href="#precipitation">precipitation</a>.
[61]	430	Also cloud-top cooling by longwave radiation can be utilized (see <a href="#radiation">radiation</a>)<br> <b><br>
	431	cloud_physics =</b> <span style="font-style: italic;">.TRUE.
[75]	432	</span>requires <a href="#humidity">humidity</a>
[61]	433	=<span style="font-style: italic;"> .TRUE.</span> .<br>
[5]	434	Detailed information about the condensation scheme is given in the
	435	description of the <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM-1/Dokumentationen/Cloud_physics/wolken.pdf">cloud
[61]	436	physics module</a> (pdf-file, only in German).<br> <br>
	437	This condensation scheme is not allowed if cloud droplets are simulated
	438	explicitly (see <a href="#cloud_droplets">cloud_droplets</a>).<br>
	439	</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="conserve_volume_flow"></a>conserve_volume_flow</span></td>
	440	<td style="vertical-align: top;">L</td> <td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td>Conservation
	441	of volume flow in x- and y-direction.<br> <br> <span style="font-weight: bold;">conserve_volume_flow</span>
	442	= <span style="font-style: italic;">.TRUE.</span>
[5]	443	guarantees that the volume flow through the xz- or yz-cross-section of
	444	the total model domain remains constant (equal to the initial value at
	445	t=0) throughout the run.<br>
[61]	446	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="cut_spline_overshoot"></a><b>cut_spline_overshoot</b></p>
	447	</td> <td style="vertical-align: top;">L</td>
	448	<td style="vertical-align: top;"><span style="font-style: italic;">.T.</span></td> <td style="vertical-align: top;"> <p>Cuts off of
	449	so-called overshoots, which can occur with the
	450	upstream-spline scheme.  </p> <p><font color="#000000">The cubic splines tend to overshoot in
[5]	451	case of discontinuous changes of variables between neighbouring grid
	452	points.</font><font color="#ff0000"> </font><font color="#000000">This
[61]	453	may lead to errors in calculating the advection tendency.</font>
	454	Choice
	455	of <b>cut_spline_overshoot</b> = <i>.TRUE.</i>
	456	(switched on by
[5]	457	default)
	458	allows variable values not to exceed an interval defined by the
	459	respective adjacent grid points. This interval can be adjusted
	460	seperately for every prognostic variable (see initialization parameters
[61]	461	<a href="#overshoot_limit_e">overshoot_limit_e</a>, <a href="#overshoot_limit_pt">overshoot_limit_pt</a>, <a href="#overshoot_limit_u">overshoot_limit_u</a>,
[5]	462	etc.). This might be necessary in case that the
	463	default interval has a non-tolerable effect on the model
[61]	464	results.  </p> <p>Overshoots may also be removed
	465	using the parameters <a href="#ups_limit_e">ups_limit_e</a>,
	466	<a href="#ups_limit_pt">ups_limit_pt</a>,
[5]	467	etc. as well as by applying a long-filter (see <a href="#long_filter_factor">long_filter_factor</a>).</p>
[61]	468	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="damp_level_1d"></a><b>damp_level_1d</b></p>
	469	</td> <td style="vertical-align: top;">R</td>
	470	<td style="vertical-align: top;"><span style="font-style: italic;">zu(nz+1)</span></td>
	471	<td style="vertical-align: top;"> <p>Height where
	472	the damping layer begins in the 1d-model
	473	(in m).  </p> <p>This parameter is used to
	474	switch on a damping layer for the
[5]	475	1d-model, which is generally needed for the damping of inertia
	476	oscillations. Damping is done by gradually increasing the value
	477	of the eddy diffusivities about 10% per vertical grid level
	478	(starting with the value at the height given by <b>damp_level_1d</b>,
[61]	479	or possibly from the next grid pint above), i.e. K<sub>m</sub>(k+1)
	480	=
[5]	481	1.1 * K<sub>m</sub>(k).
[61]	482	The values of K<sub>m</sub> are limited to 10 m**2/s at
	483	maximum.  <br>
[5]	484	This parameter only comes into effect if the 1d-model is switched on
	485	for
	486	the initialization of the 3d-model using <a href="#initializing_actions">initializing_actions</a>
[61]	487	= <span style="font-style: italic;">'set_1d-model_profiles'</span>.
	488	<br> </p> </td> </tr> <tr> <td style="vertical-align: top;"><a name="dissipation_1d"></a><span style="font-weight: bold;">dissipation_1d</span><br>
	489	</td> <td style="vertical-align: top;">C*20<br>
	490	</td> <td style="vertical-align: top;"><span style="font-style: italic;">'as_in_3d_</span><br style="font-style: italic;"> <span style="font-style: italic;">model'</span><br> </td>
	491	<td style="vertical-align: top;">Calculation method for
	492	the energy dissipation term in the TKE equation of the 1d-model.<br>
	493	<br>
	494	By default the dissipation is calculated as in the 3d-model using diss
	495	= (0.19 + 0.74 * l / l_grid) * e**1.5 / l.<br> <br>
	496	Setting <span style="font-weight: bold;">dissipation_1d</span>
	497	= <span style="font-style: italic;">'detering'</span>
	498	forces the dissipation to be calculated as diss = 0.064 * e**1.5 / l.<br>
	499	</td> </tr>
	500	<tr> <td style="vertical-align: top;"> <p><a name="dt"></a><b>dt</b></p> </td>
	501	<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">variable</span></td>
	502	<td style="vertical-align: top;"> <p>Time step for
	503	the 3d-model (in s).  </p> <p>By default, (i.e.
	504	if a Runge-Kutta scheme is used, see <a href="#timestep_scheme">timestep_scheme</a>)
[5]	505	the value of the time step is calculating after each time step
	506	(following the time step criteria) and
[61]	507	used for the next step.</p> <p>If the user assigns <b>dt</b>
	508	a value, then the time step is
[5]	509	fixed to this value throughout the whole run (whether it fulfills the
	510	time step
	511	criteria or not). However, changes are allowed for restart runs,
	512	because <b>dt</b> can also be used as a <a href="chapter_4.2.html#dt_laufparameter">run
[61]	513	parameter</a>.  </p> <p>In case that the
	514	calculated time step meets the condition<br> </p> <ul>
	515	<p><b>dt</b> < 0.00001 * <a href="chapter_4.2.html#dt_max">dt_max</a> (with dt_max
	516	= 20.0)</p> </ul> <p>the simulation will be
	517	aborted. Such situations usually arise
[5]	518	in case of any numerical problem / instability which causes a
[61]	519	non-realistic increase of the wind speed.  </p> <p>A
	520	small time step due to a large mean horizontal windspeed
[5]	521	speed may be enlarged by using a coordinate transformation (see <a href="#galilei_transformation">galilei_transformation</a>),
[61]	522	in order to spare CPU time.<br> </p> <p>If the
	523	leapfrog timestep scheme is used (see <a href="#timestep_scheme">timestep_scheme</a>)
[5]	524	a temporary time step value dt_new is calculated first, with dt_new = <a href="chapter_4.2.html#fcl_factor">cfl_factor</a>
	525	* dt_crit where dt_crit is the maximum timestep allowed by the CFL and
	526	diffusion condition. Next it is examined whether dt_new exceeds or
	527	falls below the
	528	value of the previous timestep by at
	529	least +5 % / -2%. If it is smaller, <span style="font-weight: bold;">dt</span>
	530	= dt_new is immediately used for the next timestep. If it is larger,
[61]	531	then <span style="font-weight: bold;">dt </span>=
	532	1.02 * dt_prev
[5]	533	(previous timestep) is used as the new timestep, however the time
	534	step is only increased if the last change of the time step is dated
	535	back at
	536	least 30 iterations. If dt_new is located in the interval mentioned
	537	above, then dt
	538	does not change at all. By doing so, permanent time step changes as
	539	well as large
[61]	540	sudden changes (increases) in the time step are avoided.</p> </td>
	541	</tr> <tr> <td style="vertical-align: top;">
	542	<p><a name="dt_pr_1d"></a><b>dt_pr_1d</b></p>
	543	</td> <td style="vertical-align: top;">R</td>
	544	<td style="vertical-align: top;"><span style="font-style: italic;">9999999.9</span></td>
	545	<td style="vertical-align: top;"> <p>Temporal
	546	interval of vertical profile output of the 1D-model
	547	(in s).  </p> <p>Data are written in ASCII
	548	format to file <a href="chapter_3.4.html#LIST_PROFIL_1D">LIST_PROFIL_1D</a>.
[5]	549	This parameter is only in effect if the 1d-model has been switched on
	550	for the
	551	initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
	552	= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
[61]	553	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="dt_run_control_1d"></a><b>dt_run_control_1d</b></p>
	554	</td> <td style="vertical-align: top;">R</td>
	555	<td style="vertical-align: top;"><span style="font-style: italic;">60.0</span></td> <td style="vertical-align: top;"> <p>Temporal interval of
	556	runtime control output of the 1d-model
	557	(in s).  </p> <p>Data are written in ASCII
	558	format to file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.
[5]	559	This parameter is only in effect if the 1d-model is switched on for the
	560	initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
	561	= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
[61]	562	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="dx"></a><b>dx</b></p>
	563	</td> <td style="vertical-align: top;">R</td>
	564	<td style="vertical-align: top;"><span style="font-style: italic;">1.0</span></td> <td style="vertical-align: top;"> <p>Horizontal grid
	565	spacing along the x-direction (in m).  </p> <p>Along
	566	x-direction only a constant grid spacing is allowed.</p> </td>
	567	</tr> <tr> <td style="vertical-align: top;">
	568	<p><a name="dy"></a><b>dy</b></p>
	569	</td> <td style="vertical-align: top;">R</td>
	570	<td style="vertical-align: top;"><span style="font-style: italic;">1.0</span></td> <td style="vertical-align: top;"> <p>Horizontal grid
[83]	571	spacing along the y-direction (in m).  </p> <p>Along y-direction only a constant grid spacing is allowed.</p> </td>
[61]	572	</tr> <tr> <td style="vertical-align: top;">
	573	<p><a name="dz"></a><b>dz</b></p>
	574	</td> <td style="vertical-align: top;">R</td>
	575	<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Vertical grid
	576	spacing (in m).  </p> <p>This parameter must be
	577	assigned by the user, because no
	578	default value is given.<br> </p> <p>By default, the
[5]	579	model uses constant grid spacing along z-direction, but it can be
	580	stretched using the parameters <a href="#dz_stretch_level">dz_stretch_level</a>
[61]	581	and <a href="#dz_stretch_factor">dz_stretch_factor</a>.
	582	In case of stretching, a maximum allowed grid spacing can be given by <a href="#dz_max">dz_max</a>.<br> </p> <p>Assuming
	583	a constant <span style="font-weight: bold;">dz</span>,
[5]	584	the scalar levels (zu) are calculated directly by:  </p>
[61]	585	<ul> <p>zu(0) = - dz * 0.5  <br>
	586	zu(1) = dz * 0.5</p> </ul> <p>The w-levels lie
	587	half between them:  </p> <ul> <p>zw(k) =
	588	( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
	589	<tr><td style="vertical-align: top;"><a name="dz_max"></a><span style="font-weight: bold;">dz_max</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">9999999.9</span></td><td style="vertical-align: top;">Allowed maximum vertical grid
	590	spacing (in m).<br><br>If the vertical grid is stretched
	591	(see <a href="#dz_stretch_factor">dz_stretch_factor</a>
	592	and <a href="#dz_stretch_level">dz_stretch_level</a>),
	593	<span style="font-weight: bold;">dz_max</span> can
	594	be used to limit the vertical grid spacing.</td></tr><tr>
	595	<td style="vertical-align: top;"> <p><a name="dz_stretch_factor"></a><b>dz_stretch_factor</b></p>
	596	</td> <td style="vertical-align: top;">R</td>
	597	<td style="vertical-align: top;"><span style="font-style: italic;">1.08</span></td> <td style="vertical-align: top;"> <p>Stretch factor for a
	598	vertically stretched grid (see <a href="#dz_stretch_level">dz_stretch_level</a>).
	599	</p> <p>The stretch factor should not exceed a value of
	600	approx. 1.10 -
[5]	601	1.12, otherwise the discretization errors due to the stretched grid not
[61]	602	negligible any more. (refer Kalnay de Rivas)</p> </td> </tr>
	603	<tr> <td style="vertical-align: top;"> <p><a name="dz_stretch_level"></a><b>dz_stretch_level</b></p>
	604	</td> <td style="vertical-align: top;">R</td>
	605	<td style="vertical-align: top;"><span style="font-style: italic;">100000.0</span><br> </td>
	606	<td style="vertical-align: top;"> <p>Height level
	607	above which the grid is to be stretched
	608	vertically (in m).  </p> <p>The vertical grid
	609	spacings <a href="#dz">dz</a>
	610	above this level are calculated as  </p> <ul> <p><b>dz</b>(k+1)
	611	= <b>dz</b>(k) * <a href="#dz_stretch_factor">dz_stretch_factor</a></p>
	612	</ul> <p>and used as spacings for the scalar levels (zu).
	613	The
	614	w-levels are then defined as:  </p> <ul> <p>zw(k)
	615	= ( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
	616	<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="e_min"></a>e_min</span></td>
	617	<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">0.0</span></td> <td>Minimum
	618	subgrid-scale TKE in m<sup>2</sup>s<sup>-2</sup>.<br>
	619	<br>This
	620	option adds artificial viscosity to the flow by ensuring that
	621	the
	622	subgrid-scale TKE does not fall below the minimum threshold <span style="font-weight: bold;">e_min</span>.</td> </tr>
	623	<tr> <td style="vertical-align: top;"> <p><a name="end_time_1d"></a><b>end_time_1d</b></p>
	624	</td> <td style="vertical-align: top;">R</td>
	625	<td style="vertical-align: top;"><span style="font-style: italic;">864000.0</span><br> </td>
	626	<td style="vertical-align: top;"> <p>Time to be
	627	simulated for the 1d-model (in s).  </p> <p>The
	628	default value corresponds to a simulated time of 10 days.
[5]	629	Usually, after such a period the inertia oscillations have completely
	630	decayed and the solution of the 1d-model can be regarded as stationary
	631	(see <a href="#damp_level_1d">damp_level_1d</a>).
	632	This parameter is only in effect if the 1d-model is switched on for the
	633	initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
	634	= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
[61]	635	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="fft_method"></a><b>fft_method</b></p>
	636	</td> <td style="vertical-align: top;">C * 20</td>
	637	<td style="vertical-align: top;"><span style="font-style: italic;">'system-</span><br style="font-style: italic;"> <span style="font-style: italic;">specific'</span></td>
	638	<td style="vertical-align: top;"> <p>FFT-method to
	639	be used.<br> </p> <p><br>
[5]	640	The fast fourier transformation (FFT) is used for solving the
	641	perturbation pressure equation with a direct method (see <a href="chapter_4.2.html#psolver">psolver</a>)
	642	and for calculating power spectra (see optional software packages,
	643	section <a href="chapter_4.2.html#spectra_package">4.2</a>).</p>
[61]	644	<p><br>
[5]	645	By default, system-specific, optimized routines from external
	646	vendor libraries are used. However, these are available only on certain
	647	computers and there are more or less severe restrictions concerning the
[61]	648	number of gridpoints to be used with them.<br> </p> <p>There
	649	are two other PALM internal methods available on every
[5]	650	machine (their respective source code is part of the PALM source code):</p>
[61]	651	<p>1.: The <span style="font-weight: bold;">Temperton</span>-method
[5]	652	from Clive Temperton (ECWMF) which is computationally very fast and
	653	switched on with <b>fft_method</b> = <span style="font-style: italic;">'temperton-algorithm'</span>.
	654	The number of horizontal gridpoints (nx+1, ny+1) to be used with this
[61]	655	method must be composed of prime factors 2, 3 and 5.<br> </p>
[5]	656	2.: The <span style="font-weight: bold;">Singleton</span>-method
	657	which is very slow but has no restrictions concerning the number of
[61]	658	gridpoints to be used with, switched on with <b>fft_method</b>
	659	= <span style="font-style: italic;">'singleton-algorithm'</span>.
	660	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="galilei_transformation"></a><b>galilei_transformation</b></p>
	661	</td> <td style="vertical-align: top;">L</td>
	662	<td style="vertical-align: top;"><i>.F.</i></td>
	663	<td style="vertical-align: top;">Application of a
	664	Galilei-transformation to the
[5]	665	coordinate
[61]	666	system of the model.<br><p>With <b>galilei_transformation</b>
	667	= <i>.T.,</i> a so-called
[5]	668	Galilei-transformation is switched on which ensures that the coordinate
	669	system of the model is moved along with the geostrophical wind.
	670	Alternatively, the model domain can be moved along with the averaged
	671	horizontal wind (see <a href="#use_ug_for_galilei_tr">use_ug_for_galilei_tr</a>,
	672	this can and will naturally change in time). With this method,
	673	numerical inaccuracies of the Piascek - Williams - scheme (concerns in
	674	particular the momentum advection) are minimized. Beyond that, in the
	675	majority of cases the lower relative velocities in the moved system
	676	permit a larger time step (<a href="#dt">dt</a>).
	677	Switching the transformation on is only worthwhile if the geostrophical
	678	wind (ug, vg)
	679	and the averaged horizontal wind clearly deviate from the value 0. In
	680	each case, the distance the coordinate system has been moved is written
	681	to the file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.
[61]	682	</p> <p>Non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
	683	and <a href="#bc_ns">bc_ns</a>), the specification
	684	of a gestrophic
[5]	685	wind that is not constant with height
	686	as well as e.g. stationary inhomogeneities at the bottom boundary do
[61]	687	not allow the use of this transformation.</p> </td> </tr>
	688	<tr> <td style="vertical-align: top;"> <p><a name="grid_matching"></a><b>grid_matching</b></p>
	689	</td> <td style="vertical-align: top;">C * 6</td>
	690	<td style="vertical-align: top;"><span style="font-style: italic;">'match'</span></td> <td style="vertical-align: top;">Variable to adjust the
	691	subdomain
	692	sizes in parallel runs.<br> <br>
[5]	693	For <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>,
	694	the subdomains are forced to have an identical
	695	size on all processors. In this case the processor numbers in the
	696	respective directions of the virtual processor net must fulfill certain
	697	divisor conditions concerning the grid point numbers in the three
[61]	698	directions (see <a href="#nx">nx</a>, <a href="#ny">ny</a>
[5]	699	and <a href="#nz">nz</a>).
	700	Advantage of this method is that all PEs bear the same computational
[61]	701	load.<br> <br>
[5]	702	There is no such restriction by default, because then smaller
	703	subdomains are allowed on those processors which
	704	form the right and/or north boundary of the virtual processor grid. On
	705	all other processors the subdomains are of same size. Whether smaller
	706	subdomains are actually used, depends on the number of processors and
	707	the grid point numbers used. Information about the respective settings
	708	are given in file <a href="file:///home/raasch/public_html/PALM_group/home/raasch/public_html/PALM_group/doc/app/chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.<br>
[61]	709	<br>
[5]	710	When using a multi-grid method for solving the Poisson equation (see <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">psolver</a>)
	711	only <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>
[61]	712	is allowed.<br> <br> <b>Note:</b><br>
[5]	713	In some cases for small processor numbers there may be a very bad load
	714	balancing among the
[61]	715	processors which may reduce the performance of the code.</td> </tr>
	716	<tr> <td style="vertical-align: top;"><a name="inflow_disturbance_begin"></a><b>inflow_disturbance_<br>
	717	begin</b></td> <td style="vertical-align: top;">I</td>
	718	<td style="vertical-align: top;"><span style="font-style: italic;">MIN(10,</span><br style="font-style: italic;"> <span style="font-style: italic;">nx/2 or ny/2)</span></td>
	719	<td style="vertical-align: top;">Lower
[5]	720	limit of the horizontal range for which random perturbations are to be
[61]	721	imposed on the horizontal velocity field (gridpoints).<br> <br>
[5]	722	If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
	723	or <a href="#bc_ns">bc_ns</a>),
	724	this parameter gives the gridpoint number (counted horizontally from
	725	the inflow)  from which on perturbations are imposed on the
	726	horizontal velocity field. Perturbations must be switched on with
	727	parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
[61]	728	</tr> <tr> <td style="vertical-align: top;"><a name="inflow_disturbance_end"></a><b>inflow_disturbance_<br>
	729	end</b></td> <td style="vertical-align: top;">I</td>
	730	<td style="vertical-align: top;"><span style="font-style: italic;">MIN(100,</span><br style="font-style: italic;"> <span style="font-style: italic;">3/4nx or</span><br style="font-style: italic;"> <span style="font-style: italic;">3/4ny)</span></td> <td style="vertical-align: top;">Upper
[5]	731	limit of the horizontal range for which random perturbations are
[61]	732	to be imposed on the horizontal velocity field (gridpoints).<br> <br>
[5]	733	If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
	734	or <a href="#bc_ns">bc_ns</a>),
	735	this parameter gives the gridpoint number (counted horizontally from
	736	the inflow)  unto which perturbations are imposed on the
	737	horizontal
	738	velocity field. Perturbations must be switched on with parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
[61]	739	</tr> <tr> <td style="vertical-align: top;">
	740	<p><a name="initializing_actions"></a><b>initializing_actions</b></p>
	741	</td> <td style="vertical-align: top;">C * 100</td>
	742	<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p style="font-style: normal;">Initialization actions
	743	to be carried out.  </p> <p style="font-style: normal;">This parameter does not have a
[5]	744	default value and therefore must be assigned with each model run. For
	745	restart runs <b>initializing_actions</b> = <span style="font-style: italic;">'read_restart_data'</span>
	746	must be set. For the initial run of a job chain the following values
[61]	747	are allowed:  </p> <p style="font-style: normal;"><span style="font-style: italic;">'set_constant_profiles'</span>
	748	</p> <ul> <p>A horizontal wind profile consisting
	749	of linear sections (see <a href="#ug_surface">ug_surface</a>,
	750	<a href="#ug_vertical_gradient">ug_vertical_gradient</a>,
	751	<a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
	752	and <a href="#vg_surface">vg_surface</a>, <a href="#vg_vertical_gradient">vg_vertical_gradient</a>,
	753	<a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
[5]	754	respectively) as well as a vertical temperature (humidity) profile
	755	consisting of
[61]	756	linear sections (see <a href="#pt_surface">pt_surface</a>,
	757	<a href="#pt_vertical_gradient">pt_vertical_gradient</a>,
	758	<a href="#q_surface">q_surface</a>
[5]	759	and <a href="#q_vertical_gradient">q_vertical_gradient</a>)
	760	are assumed as initial profiles. The subgrid-scale TKE is set to 0 but K<sub>m</sub>
[61]	761	and K<sub>h</sub> are set to very small values because
	762	otherwise no TKE
	763	would be generated.</p> </ul> <p style="font-style: italic;">'set_1d-model_profiles' </p>
	764	<ul> <p>The arrays of the 3d-model are initialized with
	765	the
[5]	766	(stationary) solution of the 1d-model. These are the variables e, kh,
	767	km, u, v and with Prandtl layer switched on rif, us, usws, vsws. The
	768	temperature (humidity) profile consisting of linear sections is set as
	769	for 'set_constant_profiles' and assumed as constant in time within the
	770	1d-model. For steering of the 1d-model a set of parameters with suffix
[61]	771	"_1d" (e.g. <a href="#end_time_1d">end_time_1d</a>,
	772	<a href="#damp_level_1d">damp_level_1d</a>)
	773	is available.</p> </ul> <p><span style="font-style: italic;">'by_user'</span></p><p style="margin-left: 40px;">The initialization of the arrays
	774	of the 3d-model is under complete control of the user and has to be
	775	done in routine <a href="chapter_3.5.1.html#user_init_3d_model">user_init_3d_model</a>
	776	of the user-interface.<span style="font-style: italic;"></span></p><p><span style="font-style: italic;">'initialize_vortex'</span>
	777	</p> <div style="margin-left: 40px;">The initial
	778	velocity field of the
[5]	779	3d-model corresponds to a
	780	Rankine-vortex with vertical axis. This setting may be used to test
	781	advection schemes. Free-slip boundary conditions for u and v (see <a href="#bc_uv_b">bc_uv_b</a>, <a href="#bc_uv_t">bc_uv_t</a>)
	782	are necessary. In order not to distort the vortex, an initial
	783	horizontal wind profile constant
	784	with height is necessary (to be set by <b>initializing_actions</b>
	785	= <span style="font-style: italic;">'set_constant_profiles'</span>)
	786	and some other conditions have to be met (neutral stratification,
	787	diffusion must be
	788	switched off, see <a href="#km_constant">km_constant</a>).
	789	The center of the vortex is located at jc = (nx+1)/2. It
	790	extends from k = 0 to k = nz+1. Its radius is 8 * <a href="#dx">dx</a>
	791	and the exponentially decaying part ranges to 32 * <a href="#dx">dx</a>
[61]	792	(see init_rankine.f90). </div> <p><span style="font-style: italic;">'initialize_ptanom'</span>
	793	</p> <ul> <p>A 2d-Gauss-like shape disturbance
	794	(x,y) is added to the
[5]	795	initial temperature field with radius 10.0 * <a href="#dx">dx</a>
	796	and center at jc = (nx+1)/2. This may be used for tests of scalar
	797	advection schemes
	798	(see <a href="#scalar_advec">scalar_advec</a>).
	799	Such tests require a horizontal wind profile constant with hight and
	800	diffusion
	801	switched off (see <span style="font-style: italic;">'initialize_vortex'</span>).
	802	Additionally, the buoyancy term
	803	must be switched of in the equation of motion  for w (this
[61]	804	requires the user to comment out the call of <span style="font-family: monospace;">buoyancy</span> in the
	805	source code of <span style="font-family: monospace;">prognostic_equations.f90</span>).</p>
	806	</ul> <p style="font-style: normal;">Values may be
[5]	807	combined, e.g. <b>initializing_actions</b> = <span style="font-style: italic;">'set_constant_profiles
[61]	808	initialize_vortex'</span>, but the values of <span style="font-style: italic;">'set_constant_profiles'</span>,
	809	<span style="font-style: italic;">'set_1d-model_profiles'</span>
	810	, and <span style="font-style: italic;">'by_user'</span>
	811	must not be given at the same time.</p> <p style="font-style: italic;"> </p> </td> </tr>
	812	<tr> <td style="vertical-align: top;"> <p><a name="km_constant"></a><b>km_constant</b></p>
	813	</td> <td style="vertical-align: top;">R</td>
	814	<td style="vertical-align: top;"><i>variable<br>
	815	(computed from TKE)</i></td> <td style="vertical-align: top;"> <p>Constant eddy
	816	diffusivities are used (laminar
	817	simulations).  </p> <p>If this parameter is
	818	specified, both in the 1d and in the
[5]	819	3d-model constant values for the eddy diffusivities are used in
	820	space and time with K<sub>m</sub> = <b>km_constant</b>
	821	and K<sub>h</sub> = K<sub>m</sub> / <a href="chapter_4.2.html#prandtl_number">prandtl_number</a>.
	822	The prognostic equation for the subgrid-scale TKE is switched off.
	823	Constant eddy diffusivities are only allowed with the Prandtl layer (<a href="#prandtl_layer">prandtl_layer</a>)
[61]	824	switched off.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="km_damp_max"></a><b>km_damp_max</b></p>
	825	</td> <td style="vertical-align: top;">R</td>
	826	<td style="vertical-align: top;"><span style="font-style: italic;">0.5*(dx
	827	or dy)</span></td> <td style="vertical-align: top;">Maximum
[5]	828	diffusivity used for filtering the velocity field in the vicinity of
[61]	829	the outflow (in m<sup>2</sup>/s).<br> <br>
[5]	830	When using non-cyclic lateral boundaries (see <a href="#bc_lr">bc_lr</a>
	831	or <a href="#bc_ns">bc_ns</a>),
	832	a smoothing has to be applied to the
	833	velocity field in the vicinity of the outflow in order to suppress any
	834	reflections of outgoing disturbances. Smoothing is done by increasing
	835	the eddy diffusivity along the horizontal direction which is
	836	perpendicular to the outflow boundary. Only velocity components
	837	parallel to the outflow boundary are filtered (e.g. v and w, if the
	838	outflow is along x). Damping is applied from the bottom to the top of
[61]	839	the domain.<br> <br>
[5]	840	The horizontal range of the smoothing is controlled by <a href="#outflow_damping_width">outflow_damping_width</a>
	841	which defines the number of gridpoints (counted from the outflow
	842	boundary) from where on the smoothing is applied. Starting from that
	843	point, the eddy diffusivity is linearly increased (from zero to its
	844	maximum value given by <span style="font-weight: bold;">km_damp_max</span>)
	845	until half of the damping range width, from where it remains constant
	846	up to the outflow boundary. If at a certain grid point the eddy
	847	diffusivity calculated from the flow field is larger than as described
[61]	848	above, it is used instead.<br> <br>
[5]	849	The default value of <span style="font-weight: bold;">km_damp_max</span>
[61]	850	has been empirically proven to be sufficient.</td> </tr> <tr>
	851	<td style="vertical-align: top;"> <p><a name="long_filter_factor"></a><b>long_filter_factor</b></p>
	852	</td> <td style="vertical-align: top;">R</td>
	853	<td style="vertical-align: top;"><i>0.0</i></td>
	854	<td style="vertical-align: top;"> <p>Filter factor
	855	for the so-called Long-filter.<br> </p> <p><br>
[5]	856	This filter very efficiently
	857	eliminates 2-delta-waves sometimes cauesed by the upstream-spline
	858	scheme (see Mahrer and
	859	Pielke, 1978: Mon. Wea. Rev., 106, 818-830). It works in all three
[61]	860	directions in space. A value of <b>long_filter_factor</b>
	861	= <i>0.01</i>
[5]	862	sufficiently removes the small-scale waves without affecting the
[61]	863	longer waves.<br> </p> <p>By default, the filter is
	864	switched off (= <i>0.0</i>).
[5]	865	It is exclusively applied to the tendencies calculated by the
	866	upstream-spline scheme (see <a href="#momentum_advec">momentum_advec</a>
	867	and <a href="#scalar_advec">scalar_advec</a>),
	868	not to the prognostic variables themselves. At the bottom and top
	869	boundary of the model domain the filter effect for vertical
	870	2-delta-waves is reduced. There, the amplitude of these waves is only
	871	reduced by approx. 50%, otherwise by nearly 100%.  <br>
[61]	872	Filter factors with values > <i>0.01</i> also
	873	reduce the amplitudes
[5]	874	of waves with wavelengths longer than 2-delta (see the paper by Mahrer
	875	and
[62]	876	Pielke, quoted above). </p> </td> </tr> <tr><td style="vertical-align: top;"><a name="loop_optimization"></a><span style="font-weight: bold;">loop_optimization</span></td><td style="vertical-align: top;">C*16</td><td style="vertical-align: top;"><span style="font-style: italic;">see right</span></td><td>Method used to optimize loops for solving the prognostic equations .<br><br>By
	877	default, the optimization method depends on the host on which PALM is
	878	running. On machines with vector-type CPUs, single 3d-loops are used to
	879	calculate each tendency term of each prognostic equation, while on all
	880	other machines, all prognostic equations are solved within one big loop
	881	over the two horizontal indices<span style="font-family: Courier New,Courier,monospace;"> i </span>and<span style="font-family: Courier New,Courier,monospace;"> j </span>(giving a good cache uitilization).<br><br>The default behaviour can be changed by setting either <span style="font-weight: bold;">loop_optimization</span> = <span style="font-style: italic;">'vector'</span> or <span style="font-weight: bold;">loop_optimization</span> = <span style="font-style: italic;">'cache'</span>.</td></tr><tr>
[61]	882	<td style="vertical-align: top;"><a name="mixing_length_1d"></a><span style="font-weight: bold;">mixing_length_1d</span><br>
	883	</td> <td style="vertical-align: top;">C*20<br>
	884	</td> <td style="vertical-align: top;"><span style="font-style: italic;">'as_in_3d_</span><br style="font-style: italic;"> <span style="font-style: italic;">model'</span><br> </td>
	885	<td style="vertical-align: top;">Mixing length used in the
	886	1d-model.<br> <br>
	887	By default the mixing length is calculated as in the 3d-model (i.e. it
	888	depends on the grid spacing).<br> <br>
	889	By setting <span style="font-weight: bold;">mixing_length_1d</span>
	890	= <span style="font-style: italic;">'blackadar'</span>,
[5]	891	the so-called Blackadar mixing length is used (l = kappa * z / ( 1 +
	892	kappa * z / lambda ) with the limiting value lambda = 2.7E-4 * u_g / f).<br>
[75]	893	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="humidity"></a><b>humidity</b></p>
[61]	894	</td> <td style="vertical-align: top;">L</td>
	895	<td style="vertical-align: top;"><i>.F.</i></td>
	896	<td style="vertical-align: top;"> <p>Parameter to
	897	switch on the prognostic equation for specific
	898	humidity q.<br> </p> <p>The initial vertical
	899	profile of q can be set via parameters <a href="chapter_4.1.html#q_surface">q_surface</a>, <a href="chapter_4.1.html#q_vertical_gradient">q_vertical_gradient</a>
[5]	900	and <a href="chapter_4.1.html#q_vertical_gradient_level">q_vertical_gradient_level</a>.
	901	Boundary conditions can be set via <a href="chapter_4.1.html#q_surface_initial_change">q_surface_initial_change</a>
	902	and <a href="chapter_4.1.html#surface_waterflux">surface_waterflux</a>.<br>
[61]	903	</p>
[5]	904	If the condensation scheme is switched on (<a href="chapter_4.1.html#cloud_physics">cloud_physics</a>
	905	= .TRUE.), q becomes the total liquid water content (sum of specific
[61]	906	humidity and liquid water content).</td> </tr>
	907	<tr> <td style="vertical-align: top;"> <p><a name="momentum_advec"></a><b>momentum_advec</b></p>
	908	</td> <td style="vertical-align: top;">C * 10</td>
	909	<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
	910	<td style="vertical-align: top;"> <p>Advection
	911	scheme to be used for the momentum equations.<br> <br>
[5]	912	The user can choose between the following schemes:<br>
[61]	913	<br> <br> <span style="font-style: italic;">'pw-scheme'</span><br>
	914	</p> <div style="margin-left: 40px;">The scheme of
	915	Piascek and
[5]	916	Williams (1970, J. Comp. Phys., 6,
	917	392-405) with central differences in the form C3 is used.<br>
	918	If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
[61]	919	= <span style="font-style: italic;">'leapfrog+euler'</span>
	920	the
[5]	921	advection scheme is - for the Euler-timestep - automatically switched
[61]	922	to an upstream-scheme.<br> </div> <p> </p> <p><span style="font-style: italic;">'ups-scheme'</span><br>
	923	</p> <div style="margin-left: 40px;">The
	924	upstream-spline scheme is
[5]	925	used
	926	(see Mahrer and Pielke,
	927	1978: Mon. Wea. Rev., 106, 818-830). In opposite to the
	928	Piascek-Williams scheme, this is characterized by much better numerical
	929	features (less numerical diffusion, better preservation of flow
	930	structures, e.g. vortices), but computationally it is much more
	931	expensive. In
	932	addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
[61]	933	= <span style="font-style: italic;">'</span><i>euler'</i>),
	934	i.e. the
[5]	935	timestep accuracy is only of first order.
	936	For this reason the advection of scalar variables (see <a href="#scalar_advec">scalar_advec</a>)
	937	should then also be carried out with the upstream-spline scheme,
	938	because otherwise the scalar variables would
	939	be subject to large numerical diffusion due to the upstream
[61]	940	scheme.  </div> <p style="margin-left: 40px;">Since
	941	the cubic splines used tend
[5]	942	to overshoot under
	943	certain circumstances, this effect must be adjusted by suitable
	944	filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
[61]	945	<a href="#long_filter_factor">long_filter_factor</a>,
	946	<a href="#ups_limit_pt">ups_limit_pt</a>, <a href="#ups_limit_u">ups_limit_u</a>, <a href="#ups_limit_v">ups_limit_v</a>, <a href="#ups_limit_w">ups_limit_w</a>).
[5]	947	This is always neccessary for runs with stable stratification,
	948	even if this stratification appears only in parts of the model domain.<br>
[61]	949	</p> <div style="margin-left: 40px;">With stable
	950	stratification the
[5]	951	upstream-spline scheme also
	952	produces gravity waves with large amplitude, which must be
	953	suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
[61]	954	<br> <span style="font-weight: bold;">Important: </span>The
[5]	955	upstream-spline scheme is not implemented for humidity and passive
[75]	956	scalars (see <a href="#humidity">humidity</a>
[5]	957	and <a href="#passive_scalar">passive_scalar</a>)
	958	and requires the use of a 2d-domain-decomposition. The last conditions
	959	severely restricts code optimization on several machines leading to
	960	very long execution times! The scheme is also not allowed for
	961	non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
[61]	962	and <a href="#bc_ns">bc_ns</a>).</div> </td>
	963	</tr> <tr> <td style="vertical-align: top;"><a name="netcdf_precision"></a><span style="font-weight: bold;">netcdf_precision</span><br>
	964	</td> <td style="vertical-align: top;">C*20<br>
	965	(10)<br> </td> <td style="vertical-align: top;"><span style="font-style: italic;">single preci-</span><br style="font-style: italic;"> <span style="font-style: italic;">sion for all</span><br style="font-style: italic;"> <span style="font-style: italic;">output quan-</span><br style="font-style: italic;"> <span style="font-style: italic;">tities</span><br> </td>
	966	<td style="vertical-align: top;">Defines the accuracy of
	967	the NetCDF output.<br> <br>
	968	By default, all NetCDF output data (see <a href="chapter_4.2.html#data_output_format">data_output_format</a>)
	969	have single precision  (4 byte) accuracy. Double precision (8
	970	byte) can be choosen alternatively.<br>
	971	Accuracy for the different output data (cross sections, 3d-volume data,
	972	spectra, etc.) can be set independently.<br> <span style="font-style: italic;">'<out>_NF90_REAL4'</span>
	973	(single precision) or <span style="font-style: italic;">'<out>_NF90_REAL8'</span>
	974	(double precision) are the two principally allowed values for <span style="font-weight: bold;">netcdf_precision</span>,
	975	where the string <span style="font-style: italic;">'<out>'
	976	</span>can be chosen out of the following list:<br> <br>
	977	<table style="text-align: left; width: 284px; height: 234px;" border="1" cellpadding="2" cellspacing="2"> <tbody>
	978	<tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xy'</span><br> </td>
	979	<td style="vertical-align: top;">horizontal cross section<br>
	980	</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xz'</span><br> </td>
	981	<td style="vertical-align: top;">vertical (xz) cross
	982	section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'yz'</span><br> </td>
	983	<td style="vertical-align: top;">vertical (yz) cross
	984	section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'2d'</span><br> </td>
	985	<td style="vertical-align: top;">all cross sections<br>
	986	</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'3d'</span><br> </td>
	987	<td style="vertical-align: top;">volume data<br> </td>
	988	</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'pr'</span><br> </td>
	989	<td style="vertical-align: top;">vertical profiles<br>
	990	</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'ts'</span><br> </td>
	991	<td style="vertical-align: top;">time series, particle
	992	time series<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'sp'</span><br> </td>
	993	<td style="vertical-align: top;">spectra<br> </td>
	994	</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'prt'</span><br> </td>
	995	<td style="vertical-align: top;">particles<br> </td>
	996	</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'all'</span><br> </td>
	997	<td style="vertical-align: top;">all output quantities<br>
	998	</td> </tr> </tbody> </table> <br> <span style="font-weight: bold;">Example:</span><br>
[5]	999	If all cross section data and the particle data shall be output in
[61]	1000	double precision and all other quantities in single precision, then <span style="font-weight: bold;">netcdf_precision</span> = <span style="font-style: italic;">'2d_NF90_REAL8'</span>, <span style="font-style: italic;">'prt_NF90_REAL8'</span>
	1001	has to be assigned.<br> </td> </tr>
	1002	<tr> <td style="vertical-align: top;"> <p><a name="npex"></a><b>npex</b></p> </td>
	1003	<td style="vertical-align: top;">I</td> <td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
	1004	along x-direction of the virtual
[5]	1005	processor
[61]	1006	net.  </p> <p>For parallel runs, the total
	1007	number of processors to be used
[5]	1008	is given by
[61]	1009	the <span style="font-weight: bold;">mrun</span>
	1010	option <a href="http://www.muk.uni-hannover.de/software/mrun_beschreibung.html#Opt-X">-X</a>.
[5]	1011	By default, depending on the type of the parallel computer, PALM
	1012	generates a 1d processor
	1013	net (domain decomposition along x, <span style="font-weight: bold;">npey</span>
[61]	1014	= <span style="font-style: italic;">1</span>) or a
	1015	2d-net (this is
[5]	1016	favored on machines with fast communication network). In case of a
	1017	2d-net, it is tried to make it more or less square-shaped. If, for
	1018	example, 16 processors are assigned (-X 16), a 4 * 4 processor net is
[61]	1019	generated (<span style="font-weight: bold;">npex</span>
	1020	= <span style="font-style: italic;">4</span>, <span style="font-weight: bold;">npey</span>
[5]	1021	= <span style="font-style: italic;">4</span>).
	1022	This choice is optimal for square total domains (<a href="#nx">nx</a>
	1023	= <a href="#ny">ny</a>),
	1024	since then the number of ghost points at the lateral boundarys of
	1025	the subdomains is minimal. If <span style="font-weight: bold;">nx</span>
[61]	1026	nd <span style="font-weight: bold;">ny</span>
	1027	differ extremely, the
[5]	1028	processor net should be manually adjusted using adequate values for <span style="font-weight: bold;">npex</span> and <span style="font-weight: bold;">npey</span>.  </p>
[61]	1029	<p><b>Important:</b> The value of <span style="font-weight: bold;">npex</span> * <span style="font-weight: bold;">npey</span> must exactly
	1030	correspond to the
[5]	1031	value assigned by the <span style="font-weight: bold;">mrun</span>-option
[61]	1032	<tt>-X</tt>.
[5]	1033	Otherwise the model run will abort with a corresponding error
	1034	message.  <br>
	1035	Additionally, the specification of <span style="font-weight: bold;">npex</span>
[61]	1036	and <span style="font-weight: bold;">npey</span>
	1037	may of course
[5]	1038	override the default setting for the domain decomposition (1d or 2d)
	1039	which may have a significant (negative) effect on the code performance.
[61]	1040	</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="npey"></a><b>npey</b></p>
	1041	</td> <td style="vertical-align: top;">I</td>
	1042	<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
	1043	along y-direction of the virtual
[5]	1044	processor
[61]	1045	net.  </p> <p>For further information see <a href="#npex">npex</a>.</p> </td> </tr>
	1046	<tr> <td style="vertical-align: top;"> <p><a name="nsor_ini"></a><b>nsor_ini</b></p>
	1047	</td> <td style="vertical-align: top;">I</td>
	1048	<td style="vertical-align: top;"><i>100</i></td>
	1049	<td style="vertical-align: top;"> <p>Initial number
	1050	of iterations with the SOR algorithm.  </p> <p>This
	1051	parameter is only effective if the SOR algorithm was
[5]	1052	selected as the pressure solver scheme (<a href="chapter_4.2.html#psolver">psolver</a>
[61]	1053	= <span style="font-style: italic;">'sor'</span>)
	1054	and specifies the
[5]	1055	number of initial iterations of the SOR
	1056	scheme (at t = 0). The number of subsequent iterations at the following
	1057	timesteps is determined
	1058	with the parameter <a href="#nsor">nsor</a>.
[61]	1059	Usually <b>nsor</b> < <b>nsor_ini</b>,
	1060	since in each case
[5]	1061	subsequent calls to <a href="chapter_4.2.html#psolver">psolver</a>
	1062	use the solution of the previous call as initial value. Suitable
	1063	test runs should determine whether sufficient convergence of the
	1064	solution is obtained with the default value and if necessary the value
[61]	1065	of <b>nsor_ini</b> should be changed.</p> </td>
	1066	</tr> <tr> <td style="vertical-align: top;">
	1067	<p><a name="nx"></a><b>nx</b></p>
	1068	</td> <td style="vertical-align: top;">I</td>
	1069	<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
	1070	points in x-direction.  </p> <p>A value for this
	1071	parameter must be assigned. Since the lower
[5]	1072	array bound in PALM
	1073	starts with i = 0, the actual number of grid points is equal to <b>nx+1</b>.
	1074	In case of cyclic boundary conditions along x, the domain size is (<b>nx+1</b>)*
[61]	1075	<a href="#dx">dx</a>.</p> <p>For
	1076	parallel runs, in case of <a href="#grid_matching">grid_matching</a>
	1077	= <span style="font-style: italic;">'strict'</span>,
	1078	<b>nx+1</b> must
[5]	1079	be an integral multiple
	1080	of the processor numbers (see <a href="#npex">npex</a>
	1081	and <a href="#npey">npey</a>)
	1082	along x- as well as along y-direction (due to data
[61]	1083	transposition restrictions).</p> </td> </tr> <tr>
	1084	<td style="vertical-align: top;"> <p><a name="ny"></a><b>ny</b></p>
	1085	</td> <td style="vertical-align: top;">I</td>
	1086	<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
	1087	points in y-direction.  </p> <p>A value for this
	1088	parameter must be assigned. Since the lower
[5]	1089	array bound in PALM starts with i = 0, the actual number of grid points
[61]	1090	is equal to <b>ny+1</b>. In case of cyclic boundary
	1091	conditions along
[5]	1092	y, the domain size is (<b>ny+1</b>) * <a href="#dy">dy</a>.</p>
[61]	1093	<p>For parallel runs, in case of <a href="#grid_matching">grid_matching</a>
	1094	= <span style="font-style: italic;">'strict'</span>,
	1095	<b>ny+1</b> must
[5]	1096	be an integral multiple
	1097	of the processor numbers (see <a href="#npex">npex</a>
	1098	and <a href="#npey">npey</a>)
	1099	along y- as well as along x-direction (due to data
[61]	1100	transposition restrictions).</p> </td> </tr> <tr>
	1101	<td style="vertical-align: top;"> <p><a name="nz"></a><b>nz</b></p>
	1102	</td> <td style="vertical-align: top;">I</td>
	1103	<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
	1104	points in z-direction.  </p> <p>A value for this
	1105	parameter must be assigned. Since the lower
[5]	1106	array bound in PALM
	1107	starts with k = 0 and since one additional grid point is added at the
[61]	1108	top boundary (k = <b>nz+1</b>), the actual number of grid
	1109	points is <b>nz+2</b>.
	1110	However, the prognostic equations are only solved up to <b>nz</b>
	1111	(u,
[5]	1112	v)
[61]	1113	or up to <b>nz-1</b> (w, scalar quantities). The top
	1114	boundary for u
	1115	and v is at k = <b>nz+1</b> (u, v) while at k = <b>nz</b>
	1116	for all
	1117	other quantities.  </p> <p>For parallel
	1118	runs,  in case of <a href="#grid_matching">grid_matching</a>
	1119	= <span style="font-style: italic;">'strict'</span>,
	1120	<b>nz</b> must
[5]	1121	be an integral multiple of
	1122	the number of processors in x-direction (due to data transposition
[97]	1123	restrictions).</p> </td> </tr> <tr><td style="vertical-align: top;"><a name="ocean"></a><span style="font-weight: bold;">ocean</span></td><td style="vertical-align: top;">L</td><td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td><td style="vertical-align: top;">Parameter to switch on ocean runs.<br><br>By default PALM is configured to simulate atmospheric flows. However, starting from version 3.3, <span style="font-weight: bold;">ocean</span> = <span style="font-style: italic;">.T.</span> allows simulation of ocean turbulent flows. Setting this switch has several effects:<br><br><ul><li>An additional prognostic equation for salinity is solved.</li><li>Potential temperature in buoyancy and stability-related terms is replaced by potential density.</li><li>Potential
	1124	density is calculated from the equation of state for seawater after
	1125	each timestep, using the algorithm proposed by Jackett et al. (2006, J.
	1126	Atmos. Oceanic Technol., <span style="font-weight: bold;">23</span>, 1709-1728).<br>So far, only the initial hydrostatic pressure is entered into this equation.</li><li>z=0 (sea surface) is assumed at the model top (vertical grid index <span style="font-family: Courier New,Courier,monospace;">k=nzt</span> on the w-grid), with negative values of z indicating the depth.</li><li>Initial profiles are constructed (e.g. from <a href="#pt_vertical_gradient">pt_vertical_gradient</a> / <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>) starting from the sea surface, using surface values given by <a href="#pt_surface">pt_surface</a>, <a href="#sa_surface">sa_surface</a>, <a href="#ug_surface">ug_surface</a>, and <a href="#vg_surface">vg_surface</a>.</li><li>Zero salinity flux is used as default boundary condition at the bottom of the sea.</li><li>If switched on, random perturbations are by default imposed to the upper model domain from zu(nzt*2/3) to zu(nzt-3).</li></ul><br>Relevant parameters to be exclusively used for steering ocean runs are <a href="#bc_sa_t">bc_sa_t</a>, <a href="#bottom_salinityflux">bottom_salinityflux</a>, <a href="#sa_surface">sa_surface</a>, <a href="#sa_vertical_gradient">sa_vertical_gradient</a>, <a href="#sa_vertical_gradient_level">sa_vertical_gradient_level</a>, and <a href="#top_salinityflux">top_salinityflux</a>.<br><br>Section <a href="chapter_4.2.2.html">4.4.2</a> gives an example for appropriate settings of these and other parameters neccessary for ocean runs.<br><br><span style="font-weight: bold;">ocean</span> = <span style="font-style: italic;">.T.</span> does not allow settings of <a href="#timestep_scheme">timestep_scheme</a> = <span style="font-style: italic;">'leapfrog'</span> or <span style="font-style: italic;">'leapfrog+euler'</span> as well as <a href="#scalar_advec">scalar_advec</a> = <span style="font-style: italic;">'ups-scheme'</span>.<br><br><span style="font-weight: bold;">Current limitations:</span><br>Using
	1127	a vertical grid stretching is not recommended since it would still
	1128	stretch the grid towards the top boundary of the model (sea surface)
	1129	instead of the bottom boundary.</td></tr><tr> <td style="vertical-align: top;"> <p><a name="omega"></a><b>omega</b></p>
[61]	1130	</td> <td style="vertical-align: top;">R</td>
	1131	<td style="vertical-align: top;"><i>7.29212E-5</i></td>
	1132	<td style="vertical-align: top;"> <p>Angular
	1133	velocity of the rotating system (in rad s<sup>-1</sup>).
	1134	</p> <p>The angular velocity of the earth is set by
	1135	default. The
[5]	1136	values
[61]	1137	of the Coriolis parameters are calculated as:  </p> <ul>
	1138	<p>f = 2.0 * <b>omega</b> * sin(<a href="#phi">phi</a>)
	1139	<br>f* = 2.0 * <b>omega</b> * cos(<a href="#phi">phi</a>)</p>
	1140	</ul> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="outflow_damping_width"></a><b>outflow_damping_width</b></p>
	1141	</td> <td style="vertical-align: top;">I</td>
	1142	<td style="vertical-align: top;"><span style="font-style: italic;">MIN(20,
[5]	1143	nx/2</span> or <span style="font-style: italic;">ny/2)</span></td>
[61]	1144	<td style="vertical-align: top;">Width of
[5]	1145	the damping range in the vicinity of the outflow (gridpoints).<br>
[61]	1146	<br>
[5]	1147	When using non-cyclic lateral boundaries (see <a href="chapter_4.1.html#bc_lr">bc_lr</a>
	1148	or <a href="chapter_4.1.html#bc_ns">bc_ns</a>),
	1149	a smoothing has to be applied to the
	1150	velocity field in the vicinity of the outflow in order to suppress any
	1151	reflections of outgoing disturbances. This parameter controlls the
	1152	horizontal range to which the smoothing is applied. The range is given
	1153	in gridpoints counted from the respective outflow boundary. For further
	1154	details about the smoothing see parameter <a href="chapter_4.1.html#km_damp_max">km_damp_max</a>,
[61]	1155	which defines the magnitude of the damping.</td> </tr>
	1156	<tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_e"></a><b>overshoot_limit_e</b></p>
	1157	</td> <td style="vertical-align: top;">R</td>
	1158	<td style="vertical-align: top;"><i>0.0</i></td>
	1159	<td style="vertical-align: top;"> <p>Allowed limit
	1160	for the overshooting of subgrid-scale TKE in
[5]	1161	case that the upstream-spline scheme is switched on (in m<sup>2</sup>/s<sup>2</sup>).
[61]	1162	</p> <p>By deafult, if cut-off of overshoots is switched
	1163	on for the
[5]	1164	upstream-spline scheme (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>),
	1165	no overshoots are permitted at all. If <b>overshoot_limit_e</b>
	1166	is given a non-zero value, overshoots with the respective
	1167	amplitude (both upward and downward) are allowed.  </p>
[61]	1168	<p>Only positive values are allowed for <b>overshoot_limit_e</b>.</p>
	1169	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_pt"></a><b>overshoot_limit_pt</b></p>
	1170	</td> <td style="vertical-align: top;">R</td>
	1171	<td style="vertical-align: top;"><i>0.0</i></td>
	1172	<td style="vertical-align: top;"> <p>Allowed limit
	1173	for the overshooting of potential temperature in
[5]	1174	case that the upstream-spline scheme is switched on (in K).  </p>
[61]	1175	<p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.
	1176	</p> <p>Only positive values are allowed for <b>overshoot_limit_pt</b>.</p>
	1177	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_u"></a><b>overshoot_limit_u</b></p>
	1178	</td> <td style="vertical-align: top;">R</td>
	1179	<td style="vertical-align: top;"><i>0.0</i></td>
	1180	<td style="vertical-align: top;">Allowed limit for the
[5]	1181	overshooting of
	1182	the u-component of velocity in case that the upstream-spline scheme is
[61]	1183	switched on (in m/s). <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.
	1184	</p> <p>Only positive values are allowed for <b>overshoot_limit_u</b>.</p>
	1185	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_v"></a><b>overshoot_limit_v</b></p>
	1186	</td> <td style="vertical-align: top;">R</td>
	1187	<td style="vertical-align: top;"><i>0.0</i></td>
	1188	<td style="vertical-align: top;"> <p>Allowed limit
	1189	for the overshooting of the v-component of
[5]	1190	velocity in case that the upstream-spline scheme is switched on
[61]	1191	(in m/s).  </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.
	1192	</p> <p>Only positive values are allowed for <b>overshoot_limit_v</b>.</p>
	1193	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_w"></a><b>overshoot_limit_w</b></p>
	1194	</td> <td style="vertical-align: top;">R</td>
	1195	<td style="vertical-align: top;"><i>0.0</i></td>
	1196	<td style="vertical-align: top;"> <p>Allowed limit
	1197	for the overshooting of the w-component of
[5]	1198	velocity in case that the upstream-spline scheme is switched on
[61]	1199	(in m/s).  </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.
	1200	</p> <p>Only positive values are permitted for <b>overshoot_limit_w</b>.</p>
	1201	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="passive_scalar"></a><b>passive_scalar</b></p>
	1202	</td> <td style="vertical-align: top;">L</td>
	1203	<td style="vertical-align: top;"><i>.F.</i></td>
	1204	<td style="vertical-align: top;"> <p>Parameter to
	1205	switch on the prognostic equation for a passive
	1206	scalar. <br> </p> <p>The initial vertical profile
	1207	of s can be set via parameters <a href="#s_surface">s_surface</a>,
	1208	<a href="#s_vertical_gradient">s_vertical_gradient</a>
[5]	1209	and  <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
	1210	Boundary conditions can be set via <a href="#s_surface_initial_change">s_surface_initial_change</a>
[61]	1211	and <a href="#surface_scalarflux">surface_scalarflux</a>.
	1212	</p> <p><b>Note:</b> <br>
	1213	With <span style="font-weight: bold;">passive_scalar</span>
	1214	switched
[75]	1215	on, the simultaneous use of humidity (see <a href="#humidity">humidity</a>)
[61]	1216	is impossible.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="phi"></a><b>phi</b></p>
	1217	</td> <td style="vertical-align: top;">R</td>
	1218	<td style="vertical-align: top;"><i>55.0</i></td>
	1219	<td style="vertical-align: top;"> <p>Geographical
	1220	latitude (in degrees).  </p> <p>The value of
	1221	this parameter determines the value of the
[5]	1222	Coriolis parameters f and f*, provided that the angular velocity (see <a href="#omega">omega</a>)
[61]	1223	is non-zero.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="prandtl_layer"></a><b>prandtl_layer</b></p>
	1224	</td> <td style="vertical-align: top;">L</td>
	1225	<td style="vertical-align: top;"><i>.T.</i></td>
	1226	<td style="vertical-align: top;"> <p>Parameter to
	1227	switch on a Prandtl layer.  </p> <p>By default,
	1228	a Prandtl layer is switched on at the bottom
[5]	1229	boundary between z = 0 and z = 0.5 * <a href="#dz">dz</a>
	1230	(the first computational grid point above ground for u, v and the
	1231	scalar quantities).
	1232	In this case, at the bottom boundary, free-slip conditions for u and v
	1233	(see <a href="#bc_uv_b">bc_uv_b</a>)
	1234	are not allowed. Likewise, laminar
	1235	simulations with constant eddy diffusivities (<a href="#km_constant">km_constant</a>)
[61]	1236	are forbidden.  </p> <p>With Prandtl-layer
	1237	switched off, the TKE boundary condition <a href="#bc_e_b">bc_e_b</a>
	1238	= '<i>(u)*2+neumann'</i> must not be used and is
	1239	automatically
	1240	changed to <i>'neumann'</i> if necessary.  Also,
	1241	the pressure
[5]	1242	boundary condition <a href="#bc_p_b">bc_p_b</a>
	1243	= <i>'neumann+inhomo'</i>  is not allowed. </p>
[61]	1244	<p>The roughness length is declared via the parameter <a href="#roughness_length">roughness_length</a>.</p>
	1245	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="precipitation"></a><b>precipitation</b></p>
	1246	</td> <td style="vertical-align: top;">L</td>
	1247	<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p>Parameter to switch
	1248	on the precipitation scheme.<br> </p> <p>For
	1249	precipitation processes PALM uses a simplified Kessler
[5]	1250	scheme. This scheme only considers the
	1251	so-called autoconversion, that means the generation of rain water by
	1252	coagulation of cloud drops among themselves. Precipitation begins and
	1253	is immediately removed from the flow as soon as the liquid water
[72]	1254	content exceeds the critical value of 0.5 g/kg.</p><p>The precipitation rate and amount can be output by assigning the runtime parameter <a href="chapter_4.2.html#data_output">data_output</a> = <span style="font-style: italic;">'prr'</span> or <span style="font-style: italic;">'pra'</span>, respectively. The time interval on which the precipitation amount is defined can be controlled via runtime parameter <a href="chapter_4.2.html#precipitation_amount_interval">precipitation_amount_interval</a>.</p> </td> </tr>
[61]	1255	<tr><td style="vertical-align: top;"><a name="pt_reference"></a><span style="font-weight: bold;">pt_reference</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">use horizontal average as
	1256	refrence</span></td><td style="vertical-align: top;">Reference
	1257	temperature to be used in all buoyancy terms (in K).<br><br>By
	1258	default, the instantaneous horizontal average over the total model
[97]	1259	domain is used.<br><br><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>), always a reference temperature is used in the buoyancy terms with a default value of <span style="font-weight: bold;">pt_reference</span> = <a href="#pt_surface">pt_surface</a>.</td></tr><tr> <td style="vertical-align: top;"> <p><a name="pt_surface"></a><b>pt_surface</b></p>
[61]	1260	</td> <td style="vertical-align: top;">R</td>
	1261	<td style="vertical-align: top;"><i>300.0</i></td>
	1262	<td style="vertical-align: top;"> <p>Surface
	1263	potential temperature (in K).  </p> <p>This
	1264	parameter assigns the value of the potential temperature
[97]	1265	<span style="font-weight: bold;">pt</span> at the surface (k=0)<b>.</b> Starting from this value,
[61]	1266	the
[5]	1267	initial vertical temperature profile is constructed with <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
[61]	1268	and <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level
	1269	</a>.
[97]	1270	This profile is also used for the 1d-model as a stationary profile.</p><p><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="#ocean">ocean</a>),
	1271	this parameter gives the temperature value at the sea surface, which is
	1272	at k=nzt. The profile is then constructed from the surface down to the
	1273	bottom of the model.</p>
[61]	1274	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_surface_initial_change"></a><b>pt_surface_initial</b>
	1275	<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
	1276	<td style="vertical-align: top;"> <p>Change in
	1277	surface temperature to be made at the beginning of
[5]	1278	the 3d run
[61]	1279	(in K).  </p> <p>If <b>pt_surface_initial_change</b>
	1280	is set to a non-zero
[5]	1281	value, the near surface sensible heat flux is not allowed to be given
	1282	simultaneously (see <a href="#surface_heatflux">surface_heatflux</a>).</p>
[61]	1283	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient"></a><b>pt_vertical_gradient</b></p>
	1284	</td> <td style="vertical-align: top;">R (10)</td>
	1285	<td style="vertical-align: top;"><i>10 * 0.0</i></td>
	1286	<td style="vertical-align: top;"> <p>Temperature
	1287	gradient(s) of the initial temperature profile (in
[5]	1288	K
[61]	1289	/ 100 m).  </p> <p>This temperature gradient
	1290	holds starting from the height
[5]	1291	level defined by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>
	1292	(precisely: for all uv levels k where zu(k) >
	1293	pt_vertical_gradient_level,
	1294	pt_init(k) is set: pt_init(k) = pt_init(k-1) + dzu(k) * <b>pt_vertical_gradient</b>)
	1295	up to the top boundary or up to the next height level defined
	1296	by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>.
	1297	A total of 10 different gradients for 11 height intervals (10 intervals
	1298	if <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>(1)
[61]	1299	= <i>0.0</i>) can be assigned. The surface temperature is
	1300	assigned via <a href="#pt_surface">pt_surface</a>.
	1301	</p> <p>Example:  </p> <ul> <p><b>pt_vertical_gradient</b>
	1302	= <i>1.0</i>, <i>0.5</i>,  <br>
	1303	<b>pt_vertical_gradient_level</b> = <i>500.0</i>,
	1304	<i>1000.0</i>,</p> </ul> <p>That
	1305	defines the temperature profile to be neutrally
[5]	1306	stratified
	1307	up to z = 500.0 m with a temperature given by <a href="#pt_surface">pt_surface</a>.
[61]	1308	For 500.0 m < z <= 1000.0 m the temperature gradient is
	1309	1.0 K /
[5]	1310	100 m and for z > 1000.0 m up to the top boundary it is
	1311	0.5 K / 100 m (it is assumed that the assigned height levels correspond
[97]	1312	with uv levels).</p><p><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>),
	1313	the profile is constructed like described above, but starting from the
	1314	sea surface (k=nzt) down to the bottom boundary of the model. Height
	1315	levels have then to be given as negative values, e.g. <span style="font-weight: bold;">pt_vertical_gradient_level</span> = <span style="font-style: italic;">-500.0</span>, <span style="font-style: italic;">-1000.0</span>.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient_level"></a><b>pt_vertical_gradient</b>
[61]	1316	<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>
	1317	<span style="font-style: italic;">0.0</span><br>
	1318	</p> </td> <td style="vertical-align: top;">
	1319	<p>Height level from which on the temperature gradient defined by
	1320	<a href="#pt_vertical_gradient">pt_vertical_gradient</a>
[97]	1321	is effective (in m).  </p> <p>The height levels have to be assigned in ascending order. The
[5]	1322	default values result in a neutral stratification regardless of the
	1323	values of <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
	1324	(unless the top boundary of the model is higher than 100000.0 m).
[97]	1325	For the piecewise construction of temperature profiles see <a href="#pt_vertical_gradient">pt_vertical_gradient</a>.</p><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>), the (negative) height levels have to be assigned in descending order.
[61]	1326	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface"></a><b>q_surface</b></p>
	1327	</td> <td style="vertical-align: top;">R</td>
	1328	<td style="vertical-align: top;"><i>0.0</i></td>
	1329	<td style="vertical-align: top;"> <p>Surface
	1330	specific humidity / total water content (kg/kg).  </p> <p>This
	1331	parameter assigns the value of the specific humidity q at
	1332	the surface (k=0).  Starting from this value, the initial
	1333	humidity
[5]	1334	profile is constructed with  <a href="#q_vertical_gradient">q_vertical_gradient</a>
	1335	and <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
	1336	This profile is also used for the 1d-model as a stationary profile.</p>
[61]	1337	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface_initial_change"></a><b>q_surface_initial</b>
	1338	<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R<br> </td> <td style="vertical-align: top;"><i>0.0</i></td>
	1339	<td style="vertical-align: top;"> <p>Change in
	1340	surface specific humidity / total water content to
[5]	1341	be made at the beginning
[61]	1342	of the 3d run (kg/kg).  </p> <p>If <b>q_surface_initial_change</b><i>
	1343	</i>is set to a
[5]	1344	non-zero value the
	1345	near surface latent heat flux (water flux) is not allowed to be given
	1346	simultaneously (see <a href="#surface_waterflux">surface_waterflux</a>).</p>
[61]	1347	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient"></a><b>q_vertical_gradient</b></p>
	1348	</td> <td style="vertical-align: top;">R (10)</td>
	1349	<td style="vertical-align: top;"><i>10 * 0.0</i></td>
	1350	<td style="vertical-align: top;"> <p>Humidity
	1351	gradient(s) of the initial humidity profile
	1352	(in 1/100 m).  </p> <p>This humidity gradient
	1353	holds starting from the height
[5]	1354	level  defined by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>
	1355	(precisely: for all uv levels k, where zu(k) >
	1356	q_vertical_gradient_level,
	1357	q_init(k) is set: q_init(k) = q_init(k-1) + dzu(k) * <b>q_vertical_gradient</b>)
	1358	up to the top boundary or up to the next height level defined
	1359	by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
	1360	A total of 10 different gradients for 11 height intervals (10 intervals
	1361	if <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>(1)
[61]	1362	= <i>0.0</i>) can be asigned. The surface humidity is
	1363	assigned
[5]	1364	via <a href="#q_surface">q_surface</a>. </p>
[61]	1365	<p>Example:  </p> <ul> <p><b>q_vertical_gradient</b>
	1366	= <i>0.001</i>, <i>0.0005</i>,  <br>
	1367	<b>q_vertical_gradient_level</b> = <i>500.0</i>,
	1368	<i>1000.0</i>,</p> </ul>
[5]	1369	That defines the humidity to be constant with height up to z =
	1370	500.0
	1371	m with a
	1372	value given by <a href="#q_surface">q_surface</a>.
[61]	1373	For 500.0 m < z <= 1000.0 m the humidity gradient is
	1374	0.001 / 100
[5]	1375	m and for z > 1000.0 m up to the top boundary it is
	1376	0.0005 / 100 m (it is assumed that the assigned height levels
	1377	correspond with uv
[61]	1378	levels). </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient_level"></a><b>q_vertical_gradient</b>
	1379	<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>
	1380	<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
[75]	1381	which on the humidity gradient defined by <a href="#q_vertical_gradient">q_vertical_gradient</a>
[61]	1382	is effective (in m).  </p> <p>The height levels
	1383	are to be assigned in ascending order. The
[5]	1384	default values result in a humidity constant with height regardless of
	1385	the values of <a href="#q_vertical_gradient">q_vertical_gradient</a>
	1386	(unless the top boundary of the model is higher than 100000.0 m). For
	1387	the piecewise construction of humidity profiles see <a href="#q_vertical_gradient">q_vertical_gradient</a>.</p>
[61]	1388	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="radiation"></a><b>radiation</b></p>
	1389	</td> <td style="vertical-align: top;">L</td>
	1390	<td style="vertical-align: top;"><i>.F.</i></td>
	1391	<td style="vertical-align: top;"> <p>Parameter to
	1392	switch on longwave radiation cooling at
	1393	cloud-tops.  </p> <p>Long-wave radiation
	1394	processes are parameterized by the
[5]	1395	effective emissivity, which considers only the absorption and emission
	1396	of long-wave radiation at cloud droplets. The radiation scheme can be
	1397	used only with <a href="#cloud_physics">cloud_physics</a>
[61]	1398	= .TRUE. .</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="random_generator"></a><b>random_generator</b></p>
	1399	</td> <td style="vertical-align: top;">C * 20</td>
	1400	<td style="vertical-align: top;"> <p><i>'numerical</i><br>
	1401	<i>recipes'</i></p> </td> <td style="vertical-align: top;"> <p>Random number
	1402	generator to be used for creating uniformly
	1403	distributed random numbers. <br> </p> <p>It is
	1404	used if random perturbations are to be imposed on the
[5]	1405	velocity field or on the surface heat flux field (see <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>
	1406	and <a href="chapter_4.2.html#random_heatflux">random_heatflux</a>).
	1407	By default, the "Numerical Recipes" random number generator is used.
	1408	This one provides exactly the same order of random numbers on all
	1409	different machines and should be used in particular for comparison runs.<br>
[61]	1410	<br>
[5]	1411	Besides, a system-specific generator is available ( <b>random_generator</b>
[61]	1412	= <i>'system-specific')</i> which should particularly be
	1413	used for runs
[5]	1414	on vector parallel computers (NEC), because the default generator
	1415	cannot be vectorized and therefore significantly drops down the code
[61]	1416	performance on these machines.<br> </p> <span style="font-weight: bold;">Note:</span><br>
[5]	1417	Results from two otherwise identical model runs will not be comparable
[61]	1418	one-to-one if they used different random number generators.</td> </tr>
	1419	<tr> <td style="vertical-align: top;"> <p><a name="random_heatflux"></a><b>random_heatflux</b></p>
	1420	</td> <td style="vertical-align: top;">L</td>
	1421	<td style="vertical-align: top;"><i>.F.</i></td>
	1422	<td style="vertical-align: top;"> <p>Parameter to
	1423	impose random perturbations on the internal two-dimensional near
	1424	surface heat flux field <span style="font-style: italic;">shf</span>.
	1425	<br> </p>If a near surface heat flux is used as bottom
	1426	boundary
[5]	1427	condition (see <a href="#surface_heatflux">surface_heatflux</a>),
	1428	it is by default assumed to be horizontally homogeneous. Random
[61]	1429	perturbations can be imposed on the internal
	1430	two-dimensional heat flux field <span style="font-style: italic;">shf</span> by assigning <b>random_heatflux</b>
	1431	= <i>.T.</i>. The disturbed heat flux field is calculated
	1432	by
[5]	1433	multiplying the
	1434	values at each mesh point with a normally distributed random number
	1435	with a mean value and standard deviation of 1. This is repeated after
[61]	1436	every timestep.<br> <br>
	1437	In case of a non-flat <a href="#topography">topography</a>, assigning
	1438	<b>random_heatflux</b>
	1439	= <i>.T.</i> imposes random perturbations on the
	1440	combined heat
	1441	flux field <span style="font-style: italic;">shf</span>
	1442	composed of <a href="#surface_heatflux">surface_heatflux</a>
	1443	at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
	1444	at the topography top face.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_max"></a><b>rif_max</b></p>
	1445	</td> <td style="vertical-align: top;">R</td>
	1446	<td style="vertical-align: top;"><i>1.0</i></td>
	1447	<td style="vertical-align: top;"> <p>Upper limit of
	1448	the flux-Richardson number.  </p> <p>With the
	1449	Prandtl layer switched on (see <a href="#prandtl_layer">prandtl_layer</a>),
	1450	flux-Richardson numbers (rif) are calculated for z=z<sub>p</sub>
	1451	(k=1)
[5]	1452	in the 3d-model (in the 1d model for all heights). Their values in
	1453	particular determine the
	1454	values of the friction velocity (1d- and 3d-model) and the values of
	1455	the eddy diffusivity (1d-model). With small wind velocities at the
	1456	Prandtl layer top or small vertical wind shears in the 1d-model, rif
[61]	1457	can take up unrealistic large values. They are limited by an upper (<span style="font-weight: bold;">rif_max</span>) and lower
	1458	limit (see <a href="#rif_min">rif_min</a>)
	1459	for the flux-Richardson number. The condition <b>rif_max</b>
	1460	> <b>rif_min</b>
	1461	must be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_min"></a><b>rif_min</b></p>
	1462	</td> <td style="vertical-align: top;">R</td>
	1463	<td style="vertical-align: top;"><i>- 5.0</i></td>
	1464	<td style="vertical-align: top;"> <p>Lower limit of
	1465	the flux-Richardson number.  </p> <p>For further
	1466	explanations see <a href="#rif_max">rif_max</a>.
	1467	The condition <b>rif_max</b> > <b>rif_min </b>must
	1468	be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="roughness_length"></a><b>roughness_length</b></p>
	1469	</td> <td style="vertical-align: top;">R</td>
	1470	<td style="vertical-align: top;"><i>0.1</i></td>
	1471	<td style="vertical-align: top;"> <p>Roughness
	1472	length (in m).  </p> <p>This parameter is
	1473	effective only in case that a Prandtl layer
[5]	1474	is switched
	1475	on (see <a href="#prandtl_layer">prandtl_layer</a>).</p>
[97]	1476	</td> </tr> <tr><td style="vertical-align: top;"><a name="sa_surface"></a><span style="font-weight: bold;">sa_surface</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">35.0</span></td><td style="vertical-align: top;"> <p>Surface salinity (in psu). </p>This parameter only comes into effect for ocean runs (see parameter <a href="chapter_4.1.html#ocean">ocean</a>).<p>This
	1477	parameter assigns the value of the salinity <span style="font-weight: bold;">sa</span> at the sea surface (k=nzt)<b>.</b> Starting from this value,
	1478	the
	1479	initial vertical salinity profile is constructed from the surface down to the bottom of the model (k=0) by using <a href="chapter_4.1.html#sa_vertical_gradient">sa_vertical_gradient</a>
	1480	and <a href="chapter_4.1.html#sa_vertical_gradient_level">sa_vertical_gradient_level
	1481	</a>.</p></td></tr><tr><td style="vertical-align: top;"><a name="sa_vertical_gradient"></a><span style="font-weight: bold;">sa_vertical_gradient</span></td><td style="vertical-align: top;">R(10)</td><td style="vertical-align: top;"><span style="font-style: italic;">10 * 0.0</span></td><td style="vertical-align: top;"><p>Salinity gradient(s) of the initial salinity profile (in psu
	1482	/ 100 m).  </p> <p>This parameter only comes into effect for ocean runs (see parameter <a href="chapter_4.1.html#ocean">ocean</a>).</p><p>This salinity gradient
	1483	holds starting from the height
	1484	level defined by <a href="chapter_4.1.html#sa_vertical_gradient_level">sa_vertical_gradient_level</a>
	1485	(precisely: for all uv levels k where zu(k) <
	1486	sa_vertical_gradient_level, sa_init(k) is set: sa_init(k) =
	1487	sa_init(k+1) - dzu(k+1) * <b>sa_vertical_gradient</b>) down to the bottom boundary or down to the next height level defined
	1488	by <a href="chapter_4.1.html#sa_vertical_gradient_level">sa_vertical_gradient_level</a>.
	1489	A total of 10 different gradients for 11 height intervals (10 intervals
	1490	if <a href="chapter_4.1.html#sa_vertical_gradient_level">sa_vertical_gradient_level</a>(1)
	1491	= <i>0.0</i>) can be assigned. The surface salinity at k=nzt is
	1492	assigned via <a href="chapter_4.1.html#sa_surface">sa_surface</a>.
	1493	</p> <p>Example:  </p> <ul><p><b>sa_vertical_gradient</b>
	1494	= <i>1.0</i>, <i>0.5</i>,  <br>
	1495	<b>sa_vertical_gradient_level</b> = <i>-500.0</i>,
	1496	-<i>1000.0</i>,</p></ul> <p>That
	1497	defines the salinity to be constant down to z = -500.0 m with a salinity given by <a href="chapter_4.1.html#sa_surface">sa_surface</a>.
	1498	For -500.0 m < z <= -1000.0 m the salinity gradient is
	1499	1.0 psu /
	1500	100 m and for z < -1000.0 m down to the bottom boundary it is
	1501	0.5 psu / 100 m (it is assumed that the assigned height levels correspond
	1502	with uv levels).</p></td></tr><tr><td style="vertical-align: top;"><a name="sa_vertical_gradient_level"></a><span style="font-weight: bold;">sa_vertical_gradient_level</span></td><td style="vertical-align: top;">R(10)</td><td style="vertical-align: top;"><span style="font-style: italic;">10 * 0.0</span></td><td style="vertical-align: top;"><p>Height level from which on the salinity gradient defined by <a href="chapter_4.1.html#sa_vertical_gradient">sa_vertical_gradient</a>
	1503	is effective (in m).  </p> <p>This parameter only comes into effect for ocean runs (see parameter <a href="chapter_4.1.html#ocean">ocean</a>).</p><p>The height levels have to be assigned in descending order. The
	1504	default values result in a constant salinity profile regardless of the
	1505	values of <a href="chapter_4.1.html#sa_vertical_gradient">sa_vertical_gradient</a>
	1506	(unless the bottom boundary of the model is lower than -100000.0 m).
	1507	For the piecewise construction of salinity profiles see <a href="chapter_4.1.html#sa_vertical_gradient">sa_vertical_gradient</a>.</p></td></tr><tr> <td style="vertical-align: top;"> <p><a name="scalar_advec"></a><b>scalar_advec</b></p>
[61]	1508	</td> <td style="vertical-align: top;">C * 10</td>
	1509	<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
	1510	<td style="vertical-align: top;"> <p>Advection
	1511	scheme to be used for the scalar quantities.  </p> <p>The
	1512	user can choose between the following schemes:<br> </p> <p><span style="font-style: italic;">'pw-scheme'</span><br>
	1513	</p> <div style="margin-left: 40px;">The scheme of
	1514	Piascek and
[5]	1515	Williams (1970, J. Comp. Phys., 6,
	1516	392-405) with central differences in the form C3 is used.<br>
	1517	If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
[61]	1518	= <span style="font-style: italic;">'leapfrog+euler'</span>
	1519	the
[5]	1520	advection scheme is - for the Euler-timestep - automatically switched
[61]	1521	to an upstream-scheme. <br> </div> <br> <p><span style="font-style: italic;">'bc-scheme'</span><br>
	1522	</p> <div style="margin-left: 40px;">The Bott
	1523	scheme modified by
[5]	1524	Chlond (1994, Mon.
	1525	Wea. Rev., 122, 111-125). This is a conservative monotonous scheme with
	1526	very small numerical diffusion and therefore very good conservation of
	1527	scalar flow features. The scheme however, is computationally very
	1528	expensive both because it is expensive itself and because it does (so
	1529	far) not allow specific code optimizations (e.g. cache optimization).
	1530	Choice of this
	1531	scheme forces the Euler timestep scheme to be used for the scalar
	1532	quantities. For output of horizontally averaged
	1533	profiles of the resolved / total heat flux, <a href="chapter_4.2.html#data_output_pr">data_output_pr</a>
[61]	1534	= <i>'wptBC'</i> / <i>'wptBC' </i>should
	1535	be used, instead of the
[5]	1536	standard profiles (<span style="font-style: italic;">'wpt'</span>
[61]	1537	and <span style="font-style: italic;">'wpt'</span>)
	1538	because these are
[5]	1539	too inaccurate with this scheme. However, for subdomain analysis (see <a href="#statistic_regions">statistic_regions</a>)
	1540	exactly the reverse holds: here <i>'wptBC'</i> and <i>'wptBC'</i>
[61]	1541	show very large errors and should not be used.<br> <br>
[5]	1542	This scheme is not allowed for non-cyclic lateral boundary conditions
	1543	(see <a href="#bc_lr">bc_lr</a>
[61]	1544	and <a href="#bc_ns">bc_ns</a>).<br> <br>
	1545	</div> <span style="font-style: italic;">'ups-scheme'</span><br>
	1546	<p style="margin-left: 40px;">The upstream-spline-scheme
	1547	is used
[5]	1548	(see Mahrer and Pielke,
	1549	1978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piascek
	1550	Williams scheme, this is characterized by much better numerical
	1551	features (less numerical diffusion, better preservation of flux
	1552	structures, e.g. vortices), but computationally it is much more
	1553	expensive. In
	1554	addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
[61]	1555	= <span style="font-style: italic;">'</span><i>euler'</i>),
	1556	i.e. the
[5]	1557	timestep accuracy is only first order. For this reason the advection of
	1558	momentum (see <a href="#momentum_advec">momentum_advec</a>)
	1559	should then also be carried out with the upstream-spline scheme,
	1560	because otherwise the momentum would
	1561	be subject to large numerical diffusion due to the upstream
[61]	1562	scheme.  </p> <p style="margin-left: 40px;">Since
	1563	the cubic splines used tend
[5]	1564	to overshoot under
	1565	certain circumstances, this effect must be adjusted by suitable
	1566	filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
[61]	1567	<a href="#long_filter_factor">long_filter_factor</a>,
	1568	<a href="#ups_limit_pt">ups_limit_pt</a>, <a href="#ups_limit_u">ups_limit_u</a>, <a href="#ups_limit_v">ups_limit_v</a>, <a href="#ups_limit_w">ups_limit_w</a>).
[5]	1569	This is always neccesssary for runs with stable stratification,
	1570	even if this stratification appears only in parts of the model
[61]	1571	domain.  </p> <p style="margin-left: 40px;">With
	1572	stable stratification the
[5]	1573	upstream-upline scheme also produces gravity waves with large
	1574	amplitude, which must be
	1575	suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
[61]	1576	</p> <p style="margin-left: 40px;"><span style="font-weight: bold;">Important: </span>The
[5]	1577	upstream-spline scheme is not implemented for humidity and passive
[75]	1578	scalars (see <a href="#humidity">humidity</a>
[5]	1579	and <a href="#passive_scalar">passive_scalar</a>)
	1580	and requires the use of a 2d-domain-decomposition. The last conditions
	1581	severely restricts code optimization on several machines leading to
	1582	very long execution times! This scheme is also not allowed for
	1583	non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
[61]	1584	and <a href="#bc_ns">bc_ns</a>).</p><br>A
	1585	differing advection scheme can be choosed for the subgrid-scale TKE
	1586	using parameter <a href="chapter_4.1.html#use_upstream_for_tke">use_upstream_for_tke</a>.</td>
	1587	</tr> <tr> <td style="vertical-align: top;">
	1588	<p><a name="statistic_regions"></a><b>statistic_regions</b></p>
	1589	</td> <td style="vertical-align: top;">I</td>
	1590	<td style="vertical-align: top;"><i>0</i></td>
	1591	<td style="vertical-align: top;"> <p>Number of
	1592	additional user-defined subdomains for which
[5]	1593	statistical analysis
[61]	1594	and corresponding output (profiles, time series) shall be
	1595	made.  </p> <p>By default, vertical profiles and
	1596	other statistical quantities
[5]	1597	are calculated as horizontal and/or volume average of the total model
	1598	domain. Beyond that, these calculations can also be carried out for
[61]	1599	subdomains which can be defined using the field <a href="chapter_3.5.3.html">rmask </a>within the
	1600	user-defined software
[5]	1601	(see <a href="chapter_3.5.3.html">chapter
	1602	3.5.3</a>). The number of these subdomains is determined with the
[61]	1603	parameter <b>statistic_regions</b>. Maximum 9 additional
	1604	subdomains
[5]	1605	are allowed. The parameter <a href="chapter_4.3.html#region">region</a>
	1606	can be used to assigned names (identifier) to these subdomains which
	1607	are then used in the headers
[61]	1608	of the output files and plots.</p><p>If the default NetCDF
	1609	output format is selected (see parameter <a href="chapter_4.2.html#data_output_format">data_output_format</a>),
	1610	data for the total domain and all defined subdomains are output to the
	1611	same file(s) (<a href="chapter_3.4.html#DATA_1D_PR_NETCDF">DATA_1D_PR_NETCDF</a>,
	1612	<a href="chapter_3.4.html#DATA_1D_TS_NETCDF">DATA_1D_TS_NETCDF</a>).
	1613	In case of <span style="font-weight: bold;">statistic_regions</span>
	1614	> <span style="font-style: italic;">0</span>,
[5]	1615	data on the file for the different domains can be distinguished by a
	1616	suffix which is appended to the quantity names. Suffix 0 means data for
[61]	1617	the total domain, suffix 1 means data for subdomain 1, etc.</p><p>In
	1618	case of <span style="font-weight: bold;">data_output_format</span>
	1619	= <span style="font-style: italic;">'profil'</span>,
	1620	individual local files for profiles (<a href="chapter_3.4.html#PLOT1D_DATA">PLOT1D_DATA</a>) are
	1621	created for each subdomain. The individual subdomain files differ by
	1622	their name (the
[5]	1623	number of the respective subdomain is attached, e.g.
[48]	1624	PLOT1D_DATA_1). In this case the name of the file with the data of
	1625	the total domain is PLOT1D_DATA_0. If no subdomains
[61]	1626	are declared (<b>statistic_regions</b> = <i>0</i>),
	1627	the name
[48]	1628	PLOT1D_DATA is used (this must be considered in the
[61]	1629	respective file connection statements of the <span style="font-weight: bold;">mrun</span> configuration
	1630	file).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_heatflux"></a><b>surface_heatflux</b></p>
	1631	</td> <td style="vertical-align: top;">R</td>
	1632	<td style="vertical-align: top;"><span style="font-style: italic;">no prescribed<br>
	1633	heatflux<br> </span></td> <td style="vertical-align: top;"> <p>Kinematic sensible
	1634	heat flux at the bottom surface (in K m/s).  </p> <p>If
	1635	a value is assigned to this parameter, the internal two-dimensional
	1636	surface heat flux field <span style="font-style: italic;">shf</span>
	1637	is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span> as
	1638	bottom (horizontally homogeneous) boundary condition for the
[5]	1639	temperature equation. This additionally requires that a Neumann
	1640	condition must be used for the potential temperature (see <a href="#bc_pt_b">bc_pt_b</a>),
	1641	because otherwise the resolved scale may contribute to
	1642	the surface flux so that a constant value cannot be guaranteed. Also,
	1643	changes of the
	1644	surface temperature (see <a href="#pt_surface_initial_change">pt_surface_initial_change</a>)
	1645	are not allowed. The parameter <a href="#random_heatflux">random_heatflux</a>
[61]	1646	can be used to impose random perturbations on the (homogeneous) surface
	1647	heat
[5]	1648	flux field <span style="font-style: italic;">shf</span>. </p>
[61]	1649	<p>
	1650	In case of a non-flat <a href="#topography">topography</a>, the
	1651	internal two-dimensional surface heat
	1652	flux field <span style="font-style: italic;">shf</span>
	1653	is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span>
	1654	at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
	1655	at the topography top face. The parameter<a href="#random_heatflux"> random_heatflux</a>
	1656	can be used to impose random perturbations on this combined surface
	1657	heat
	1658	flux field <span style="font-style: italic;">shf</span>.
	1659	</p> <p>If no surface heat flux is assigned, <span style="font-style: italic;">shf</span> is calculated
	1660	at each timestep by u<sub></sub> theta<sub>*</sub>
	1661	(of course only with <a href="#prandtl_layer">prandtl_layer</a>
	1662	switched on). Here, u<sub>*</sub>
	1663	and theta<sub>*</sub> are calculated from the Prandtl law
	1664	assuming
[5]	1665	logarithmic wind and temperature
	1666	profiles between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_pt_b">bc_pt_b</a>)
[61]	1667	must be used as bottom boundary condition for the potential temperature.</p><p>See
	1668	also <a href="#top_heatflux">top_heatflux</a>.</p>
	1669	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_pressure"></a><b>surface_pressure</b></p>
	1670	</td> <td style="vertical-align: top;">R</td>
	1671	<td style="vertical-align: top;"><i>1013.25</i></td>
	1672	<td style="vertical-align: top;"> <p>Atmospheric
	1673	pressure at the surface (in hPa).  </p>
[5]	1674	Starting from this surface value, the vertical pressure
	1675	profile is calculated once at the beginning of the run assuming a
	1676	neutrally stratified
	1677	atmosphere. This is needed for
	1678	converting between the liquid water potential temperature and the
	1679	potential temperature (see <a href="#cloud_physics">cloud_physics</a><span style="text-decoration: underline;"></span>).</td>
[61]	1680	</tr> <tr> <td style="vertical-align: top;">
	1681	<p><a name="surface_scalarflux"></a><b>surface_scalarflux</b></p>
	1682	</td> <td style="vertical-align: top;">R</td>
	1683	<td style="vertical-align: top;"><i>0.0</i></td>
	1684	<td style="vertical-align: top;"> <p>Scalar flux at
	1685	the surface (in kg/(m<sup>2</sup> s)).  </p>
	1686	<p>If a non-zero value is assigned to this parameter, the
[5]	1687	respective scalar flux value is used
	1688	as bottom (horizontally homogeneous) boundary condition for the scalar
[61]	1689	concentration equation. This additionally requires that a
	1690	Neumann
[5]	1691	condition must be used for the scalar concentration (see <a href="#bc_s_b">bc_s_b</a>),
	1692	because otherwise the resolved scale may contribute to
	1693	the surface flux so that a constant value cannot be guaranteed. Also,
	1694	changes of the
	1695	surface scalar concentration (see <a href="#s_surface_initial_change">s_surface_initial_change</a>)
[61]	1696	are not allowed. <br> </p> <p>If no surface scalar
	1697	flux is assigned (<b>surface_scalarflux</b>
[5]	1698	= <i>0.0</i>),
	1699	it is calculated at each timestep by u<sub></sub> s<sub>*</sub>
	1700	(of course only with Prandtl layer switched on). Here, s<sub>*</sub>
	1701	is calculated from the Prandtl law assuming a logarithmic scalar
	1702	concentration
	1703	profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_s_b">bc_s_b</a>)
	1704	must be used as bottom boundary condition for the scalar concentration.</p>
[61]	1705	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_waterflux"></a><b>surface_waterflux</b></p>
	1706	</td> <td style="vertical-align: top;">R</td>
	1707	<td style="vertical-align: top;"><i>0.0</i></td>
	1708	<td style="vertical-align: top;"> <p>Kinematic
	1709	water flux near the surface (in m/s).  </p> <p>If
	1710	a non-zero value is assigned to this parameter, the
[5]	1711	respective water flux value is used
	1712	as bottom (horizontally homogeneous) boundary condition for the
	1713	humidity equation. This additionally requires that a Neumann
	1714	condition must be used for the specific humidity / total water content
	1715	(see <a href="#bc_q_b">bc_q_b</a>),
	1716	because otherwise the resolved scale may contribute to
	1717	the surface flux so that a constant value cannot be guaranteed. Also,
	1718	changes of the
	1719	surface humidity (see <a href="#q_surface_initial_change">q_surface_initial_change</a>)
[61]	1720	are not allowed.<br> </p> <p>If no surface water
	1721	flux is assigned (<b>surface_waterflux</b>
[5]	1722	= <i>0.0</i>),
	1723	it is calculated at each timestep by u<sub></sub> q<sub>*</sub>
	1724	(of course only with Prandtl layer switched on). Here, q<sub>*</sub>
	1725	is calculated from the Prandtl law assuming a logarithmic temperature
	1726	profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_q_b">bc_q_b</a>)
	1727	must be used as the bottom boundary condition for the humidity.</p>
[61]	1728	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_surface"></a><b>s_surface</b></p>
	1729	</td> <td style="vertical-align: top;">R</td>
	1730	<td style="vertical-align: top;"><i>0.0</i></td>
	1731	<td style="vertical-align: top;"> <p>Surface value
	1732	of the passive scalar (in kg/m<sup>3</sup>). <br>
	1733	</p>
[5]	1734	This parameter assigns the value of the passive scalar s at
	1735	the surface (k=0)<b>.</b> Starting from this value, the
	1736	initial vertical scalar concentration profile is constructed with<a href="#s_vertical_gradient">
	1737	s_vertical_gradient</a> and <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.</td>
[61]	1738	</tr> <tr> <td style="vertical-align: top;">
	1739	<p><a name="s_surface_initial_change"></a><b>s_surface_initial</b>
	1740	<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><i>0.0</i></td>
	1741	<td style="vertical-align: top;"> <p>Change in
	1742	surface scalar concentration to be made at the
[5]	1743	beginning of the 3d run (in kg/m<sup>3</sup>).  </p>
[61]	1744	<p>If <b>s_surface_initial_change</b><i> </i>is
	1745	set to a
[5]	1746	non-zero
	1747	value, the near surface scalar flux is not allowed to be given
	1748	simultaneously (see <a href="#surface_scalarflux">surface_scalarflux</a>).</p>
[61]	1749	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient"></a><b>s_vertical_gradient</b></p>
	1750	</td> <td style="vertical-align: top;">R (10)</td>
	1751	<td style="vertical-align: top;"><i>10 * 0</i><i>.0</i></td>
	1752	<td style="vertical-align: top;"> <p>Scalar
	1753	concentration gradient(s) of the initial scalar
[5]	1754	concentration profile (in kg/m<sup>3 </sup>/
[61]	1755	100 m).  </p> <p>The scalar gradient holds
	1756	starting from the height level
[5]	1757	defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level
[61]	1758	</a>(precisely: for all uv levels k, where zu(k) >
[5]	1759	s_vertical_gradient_level, s_init(k) is set: s_init(k) = s_init(k-1) +
[61]	1760	dzu(k) * <b>s_vertical_gradient</b>) up to the top
	1761	boundary or up to
[5]	1762	the next height level defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
	1763	A total of 10 different gradients for 11 height intervals (10 intervals
	1764	if <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>(1)
[61]	1765	= <i>0.0</i>) can be assigned. The surface scalar value is
	1766	assigned
	1767	via <a href="#s_surface">s_surface</a>.<br> </p>
	1768	<p>Example:  </p> <ul> <p><b>s_vertical_gradient</b>
	1769	= <i>0.1</i>, <i>0.05</i>,  <br>
	1770	<b>s_vertical_gradient_level</b> = <i>500.0</i>,
	1771	<i>1000.0</i>,</p> </ul> <p>That
	1772	defines the scalar concentration to be constant with
[5]	1773	height up to z = 500.0 m with a value given by <a href="#s_surface">s_surface</a>.
	1774	For 500.0 m < z <= 1000.0 m the scalar gradient is 0.1
[61]	1775	kg/m<sup>3 </sup>/ 100 m and for z > 1000.0 m up to
	1776	the top
	1777	boundary it is 0.05 kg/m<sup>3 </sup>/ 100 m (it is
	1778	assumed that the
[5]	1779	assigned height levels
	1780	correspond with uv
[61]	1781	levels).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient_level"></a><b>s_vertical_gradient_</b>
	1782	<br> <b>level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>
	1783	<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
	1784	which on the scalar gradient defined by <a href="#s_vertical_gradient">s_vertical_gradient</a>
	1785	is effective (in m).  </p> <p>The height levels
	1786	are to be assigned in ascending order. The
[5]	1787	default values result in a scalar concentration constant with height
	1788	regardless of the values of <a href="#s_vertical_gradient">s_vertical_gradient</a>
	1789	(unless the top boundary of the model is higher than 100000.0 m). For
	1790	the
	1791	piecewise construction of scalar concentration profiles see <a href="#s_vertical_gradient">s_vertical_gradient</a>.</p>
[61]	1792	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="timestep_scheme"></a><b>timestep_scheme</b></p>
	1793	</td> <td style="vertical-align: top;">C * 20</td>
	1794	<td style="vertical-align: top;"> <p><i>'runge</i><br>
	1795	<i>kutta-3'</i></p> </td> <td style="vertical-align: top;"> <p>Time step scheme to
	1796	be used for the integration of the prognostic
	1797	variables.  </p> <p>The user can choose between
	1798	the following schemes:<br> </p> <p><span style="font-style: italic;">'runge-kutta-3'</span><br>
	1799	</p> <div style="margin-left: 40px;">Third order
	1800	Runge-Kutta scheme.<br>
[5]	1801	This scheme requires the use of <a href="#momentum_advec">momentum_advec</a>
	1802	= <a href="#scalar_advec">scalar_advec</a>
[61]	1803	= '<i>pw-scheme'</i>. Please refer to the <a href="../tec/numerik.heiko/zeitschrittverfahren.pdf">documentation
	1804	on PALM's time integration schemes (28p., in German)</a>
	1805	fur further details.<br> </div> <p><span style="font-style: italic;">'runge-kutta-2'</span><br>
	1806	</p> <div style="margin-left: 40px;">Second order
	1807	Runge-Kutta scheme.<br>
[5]	1808	For special features see <b>timestep_scheme</b> = '<i>runge-kutta-3'</i>.<br>
[61]	1809	</div> <br> <span style="font-style: italic;"><span style="font-style: italic;">'leapfrog'</span><br>
	1810	<br> </span> <div style="margin-left: 40px;">Second
	1811	order leapfrog scheme.<br>
[5]	1812	Although this scheme requires a constant timestep (because it is
	1813	centered in time),  is even applied in case of changes in
	1814	timestep. Therefore, only small
	1815	changes of the timestep are allowed (see <a href="#dt">dt</a>).
	1816	However, an Euler timestep is always used as the first timestep of an
	1817	initiali run. When using the Bott-Chlond scheme for scalar advection
	1818	(see <a href="#scalar_advec">scalar_advec</a>),
	1819	the prognostic equation for potential temperature will be calculated
	1820	with the Euler scheme, although the leapfrog scheme is switched
	1821	on.  <br>
	1822	The leapfrog scheme must not be used together with the upstream-spline
	1823	scheme for calculating the advection (see <a href="#scalar_advec">scalar_advec</a>
	1824	= '<i>ups-scheme'</i> and <a href="#momentum_advec">momentum_advec</a>
[61]	1825	= '<i>ups-scheme'</i>).<br> </div> <br>
	1826	<span style="font-style: italic;">'</span><span style="font-style: italic;"><span style="font-style: italic;">leapfrog+euler'</span><br>
	1827	<br> </span> <div style="margin-left: 40px;">The
	1828	leapfrog scheme is used, but
[5]	1829	after each change of a timestep an Euler timestep is carried out.
	1830	Although this method is theoretically correct (because the pure
	1831	leapfrog method does not allow timestep changes), the divergence of the
	1832	velocity field (after applying the pressure solver) may be
	1833	significantly larger than with <span style="font-style: italic;">'leapfrog'</span>.<br>
[61]	1834	</div> <br> <span style="font-style: italic;">'euler'</span><br>
	1835	<br> <div style="margin-left: 40px;">First order
	1836	Euler scheme.  <br>
[5]	1837	The Euler scheme must be used when treating the advection terms with
	1838	the upstream-spline scheme (see <a href="#scalar_advec">scalar_advec</a>
[61]	1839	= <span style="font-style: italic;">'ups-scheme'</span>
	1840	and <a href="#momentum_advec">momentum_advec</a>
[5]	1841	= <span style="font-style: italic;">'ups-scheme'</span>).</div>
[61]	1842	<br><br>A differing timestep scheme can be choosed for the
	1843	subgrid-scale TKE using parameter <a href="#use_upstream_for_tke">use_upstream_for_tke</a>.<br>
	1844	</td> </tr> <tr> <td style="text-align: left; vertical-align: top;"><span style="font-weight: bold;"><a name="topography"></a></span><span style="font-weight: bold;">topography</span></td>
	1845	<td style="vertical-align: top;">C * 40</td> <td style="vertical-align: top;"><span style="font-style: italic;">'flat'</span></td> <td>
	1846	<p>Topography mode.  </p> <p>The user can
	1847	choose between the following modes:<br> </p> <p><span style="font-style: italic;">'flat'</span><br> </p>
	1848	<div style="margin-left: 40px;">Flat surface.</div> <p><span style="font-style: italic;">'single_building'</span><br>
	1849	</p> <div style="margin-left: 40px;">Flow
	1850	around a single rectangular building mounted on a flat surface.<br>
[5]	1851	The building size and location can be specified with the parameters <a href="#building_height">building_height</a>, <a href="#building_length_x">building_length_x</a>, <a href="#building_length_y">building_length_y</a>, <a href="#building_wall_left">building_wall_left</a> and <a href="#building_wall_south">building_wall_south</a>.</div>
[61]	1852	<span style="font-style: italic;"></span> <p><span style="font-style: italic;">'read_from_file'</span><br>
	1853	</p> <div style="margin-left: 40px;">Flow around
	1854	arbitrary topography.<br>
	1855	This mode requires the input file <a href="chapter_3.4.html#TOPOGRAPHY_DATA">TOPOGRAPHY_DATA</a><font color="#000000">. This file contains </font><font color="#000000"><font color="#000000">the </font></font><font color="#000000">arbitrary topography </font><font color="#000000"><font color="#000000">height
	1856	information</font></font><font color="#000000">
	1857	in m. These data <span style="font-style: italic;"></span>must
	1858	exactly match the horizontal grid.</font> </div> <span style="font-style: italic;"><br> </span><font color="#000000">
	1859	Alternatively, the user may add code to the user interface subroutine <a href="chapter_3.5.1.html#user_init_grid">user_init_grid</a>
	1860	to allow further topography modes.<br> <br>
	1861	All non-flat <span style="font-weight: bold;">topography</span>
	1862	modes </font>require the use of <a href="#momentum_advec">momentum_advec</a>
[5]	1863	= <a href="#scalar_advec">scalar_advec</a>
[61]	1864	= '<i>pw-scheme'</i>, <a href="chapter_4.2.html#psolver">psolver</a>
	1865	= <i>'poisfft'</i> or '<i>poisfft_hybrid'</i>,
	1866	<i> </i><a href="#alpha_surface">alpha_surface</a>
	1867	= 0.0, <a href="#bc_lr">bc_lr</a> = <a href="#bc_ns">bc_ns</a> = <span style="font-style: italic;">'cyclic'</span>, <a style="" href="#galilei_transformation">galilei_transformation</a>
[75]	1868	= <span style="font-style: italic;">.F.</span>, <a href="#cloud_physics">cloud_physics </a> = <span style="font-style: italic;">.F.</span>,  <a href="#cloud_droplets">cloud_droplets</a> = <span style="font-style: italic;">.F.</span>,  <a href="#humidity">humidity</a> = <span style="font-style: italic;">.F.</span>, and <a href="#prandtl_layer">prandtl_layer</a> = .T..<br>
[61]	1869	<font color="#000000"><br>
	1870	Note that an inclined model domain requires the use of <span style="font-weight: bold;">topography</span> = <span style="font-style: italic;">'flat'</span> and a
	1871	nonzero </font><a href="#alpha_surface">alpha_surface</a>.</td>
	1872	</tr> <tr><td style="vertical-align: top;"><a name="top_heatflux"></a><span style="font-weight: bold;">top_heatflux</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">no prescribed<br>
	1873	heatflux</span></td><td style="vertical-align: top;"><p>Kinematic
	1874	sensible heat flux at the top boundary (in K m/s).  </p>
	1875	<p>If a value is assigned to this parameter, the internal
	1876	two-dimensional surface heat flux field <span style="font-family: monospace;">tswst</span> is
	1877	initialized with the value of <span style="font-weight: bold;">top_heatflux</span> as
	1878	top (horizontally homogeneous) boundary condition for the
[40]	1879	temperature equation. This additionally requires that a Neumann
	1880	condition must be used for the potential temperature (see <a href="chapter_4.1.html#bc_pt_t">bc_pt_t</a>),
	1881	because otherwise the resolved scale may contribute to
[103]	1882	the top flux so that a constant flux value cannot be guaranteed.<span style="font-style: italic;"></span> </p>
[61]	1883	<p><span style="font-weight: bold;">Note:</span><br>The
	1884	application of a top heat flux additionally requires the setting of
	1885	initial parameter <a href="#use_top_fluxes">use_top_fluxes</a>
	1886	= .T..<span style="font-style: italic;"></span><span style="font-weight: bold;"></span> </p><p>No
	1887	Prandtl-layer is available at the top boundary so far.</p><p>See
	1888	also <a href="#surface_heatflux">surface_heatflux</a>.</p>
[103]	1889	</td></tr><tr><td style="vertical-align: top;"><a name="top_momentumflux_u"></a><span style="font-weight: bold;">top_momentumflux_u</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">no prescribed momentumflux</span></td><td style="vertical-align: top;">Momentum flux along x at the top boundary (in m2/s2).<br><p>If a value is assigned to this parameter, the internal
	1890	two-dimensional u-momentum flux field <span style="font-family: monospace;">uswst</span> is
	1891	initialized with the value of <span style="font-weight: bold;">top_momentumflux_u</span> as
	1892	top (horizontally homogeneous) boundary condition for the u-momentum equation.</p><p><span style="font-weight: bold;">Notes:</span><br>The
	1893	application of a top momentum flux additionally requires the setting of
	1894	initial parameter <a href="chapter_4.1.html#use_top_fluxes">use_top_fluxes</a>
	1895	= .T.. Setting of <span style="font-weight: bold;">top_momentumflux_u</span> requires setting of <a href="#top_momentumflux_v">top_momentumflux_v</a> also.</p><p>A Neumann
	1896	condition should be used for the u velocity component (see <a href="chapter_4.1.html#bc_uv_t">bc_uv_t</a>),
	1897	because otherwise the resolved scale may contribute to
	1898	the top flux so that a constant flux value cannot be guaranteed.<span style="font-style: italic;"></span> </p>
	1899	<span style="font-weight: bold;"></span><p>No
	1900	Prandtl-layer is available at the top boundary so far.</p></td></tr><tr><td style="vertical-align: top;"><a name="top_momentumflux_v"></a><span style="font-weight: bold;">top_momentumflux_v</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">no prescribed momentumflux</span></td><td style="vertical-align: top;">Momentum flux along y at the top boundary (in m2/s2).<br><p>If a value is assigned to this parameter, the internal
	1901	two-dimensional v-momentum flux field <span style="font-family: monospace;">vswst</span> is
	1902	initialized with the value of <span style="font-weight: bold;">top_momentumflux_v</span> as
	1903	top (horizontally homogeneous) boundary condition for the v-momentum equation.</p><p><span style="font-weight: bold;">Notes:</span><br>The
	1904	application of a top momentum flux additionally requires the setting of
	1905	initial parameter <a href="chapter_4.1.html#use_top_fluxes">use_top_fluxes</a>
	1906	= .T.. Setting of <span style="font-weight: bold;">top_momentumflux_v</span> requires setting of <a href="chapter_4.1.html#top_momentumflux_u">top_momentumflux_u</a> also.</p><p>A Neumann
	1907	condition should be used for the v velocity component (see <a href="chapter_4.1.html#bc_uv_t">bc_uv_t</a>),
	1908	because otherwise the resolved scale may contribute to
	1909	the top flux so that a constant flux value cannot be guaranteed.<span style="font-style: italic;"></span> </p>
	1910	<span style="font-weight: bold;"></span><p>No
	1911	Prandtl-layer is available at the top boundary so far.</p></td></tr><tr><td style="vertical-align: top;"><a name="top_salinityflux"></a><span style="font-weight: bold;">top_salinityflux</span></td><td style="vertical-align: top;">R</td><td style="vertical-align: top;"><span style="font-style: italic;">no prescribed<br>
[97]	1912	salinityflux</span></td><td style="vertical-align: top;"><p>Kinematic
	1913	salinity flux at the top boundary, i.e. the sea surface (in psu m/s).  </p>
	1914	<p>This parameter only comes into effect for ocean runs (see parameter <a href="chapter_4.1.html#ocean">ocean</a>).</p><p>If a value is assigned to this parameter, the internal
	1915	two-dimensional surface heat flux field <span style="font-family: monospace;">saswst</span> is
	1916	initialized with the value of <span style="font-weight: bold;">top_salinityflux</span> as
	1917	top (horizontally homogeneous) boundary condition for the salinity equation. This additionally requires that a Neumann
	1918	condition must be used for the salinity (see <a href="chapter_4.1.html#bc_sa_t">bc_sa_t</a>),
	1919	because otherwise the resolved scale may contribute to
[103]	1920	the top flux so that a constant flux value cannot be guaranteed.<span style="font-style: italic;"></span> </p>
[97]	1921	<p><span style="font-weight: bold;">Note:</span><br>The
	1922	application of a salinity flux at the model top additionally requires the setting of
	1923	initial parameter <a href="chapter_4.1.html#use_top_fluxes">use_top_fluxes</a>
	1924	= .T..<span style="font-style: italic;"></span><span style="font-weight: bold;"></span> </p><p>See
	1925	also <a href="chapter_4.1.html#bottom_salinityflux">bottom_salinityflux</a>.</p></td></tr><tr> <td style="vertical-align: top;">
[61]	1926	<p><a name="ug_surface"></a><span style="font-weight: bold;">ug_surface</span></p>
	1927	</td> <td style="vertical-align: top;">R<br> </td>
	1928	<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
	1929	<td style="vertical-align: top;">u-component of the
	1930	geostrophic
	1931	wind at the surface (in m/s).<br> <br>
[5]	1932	This parameter assigns the value of the u-component of the geostrophic
	1933	wind (ug) at the surface (k=0). Starting from this value, the initial
	1934	vertical profile of the <br>
[61]	1935	u-component of the geostrophic wind is constructed with <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
	1936	and <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
	1937	The
[5]	1938	profile constructed in that way is used for creating the initial
	1939	vertical velocity profile of the 3d-model. Either it is applied, as it
	1940	has been specified by the user (<a href="#initializing_actions">initializing_actions</a>
	1941	= 'set_constant_profiles') or it is used for calculating a stationary
	1942	boundary layer wind profile (<a href="#initializing_actions">initializing_actions</a>
[61]	1943	= 'set_1d-model_profiles'). If ug is constant with height (i.e. ug(k)=<span style="font-weight: bold;">ug_surface</span>)
	1944	and  has a large
[5]	1945	value, it is recommended to use a Galilei-transformation of the
	1946	coordinate system, if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
[97]	1947	in order to obtain larger time steps.<br><br><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>),
	1948	this parameter gives the velocity value at the sea surface, which is
	1949	at k=nzt. The profile is then constructed from the surface down to the
	1950	bottom of the model.<br> </td> </tr>
[61]	1951	<tr> <td style="vertical-align: top;"> <p><a name="ug_vertical_gradient"></a><span style="font-weight: bold;">ug_vertical_gradient</span></p>
	1952	</td> <td style="vertical-align: top;">R(10)<br>
	1953	</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
	1954	* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
	1955	profile of the  u-component of the geostrophic wind (in
	1956	1/100s).<br> <br>
[5]	1957	The gradient holds starting from the height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
	1958	(precisely: for all uv levels k where zu(k) > <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>,
[61]	1959	ug(k) is set: ug(k) = ug(k-1) + dzu(k) * <span style="font-weight: bold;">ug_vertical_gradient</span>)
	1960	up to the top
	1961	boundary or up to the next height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
	1962	A
[5]	1963	total of 10 different gradients for 11 height intervals (10
	1964	intervals  if <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>(1)
[97]	1965	= 0.0) can be assigned. The surface geostrophic wind is assigned by <a href="#ug_surface">ug_surface</a>.<br><br><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>),
	1966	the profile is constructed like described above, but starting from the
	1967	sea surface (k=nzt) down to the bottom boundary of the model. Height
	1968	levels have then to be given as negative values, e.g. <span style="font-weight: bold;">ug_vertical_gradient_level</span> = <span style="font-style: italic;">-500.0</span>, <span style="font-style: italic;">-1000.0</span>.<br> </td>
[61]	1969	</tr> <tr> <td style="vertical-align: top;">
	1970	<p><a name="ug_vertical_gradient_level"></a><span style="font-weight: bold;">ug_vertical_gradient_level</span></p>
	1971	</td> <td style="vertical-align: top;">R(10)<br>
	1972	</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
	1973	* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
[5]	1974	gradient defined by <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
[61]	1975	is effective (in m).<br> <br>
[97]	1976	The height levels have to be assigned in ascending order. For the
[5]	1977	piecewise construction of a profile of the u-component of the
[97]	1978	geostrophic wind component (ug) see <a href="#ug_vertical_gradient">ug_vertical_gradient</a>.<br><br><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>), the (negative) height levels have to be assigned in descending order.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_e"></a><b>ups_limit_e</b></p>
[61]	1979	</td> <td style="vertical-align: top;">R</td>
	1980	<td style="vertical-align: top;"><i>0.0</i></td>
	1981	<td style="vertical-align: top;"> <p>Subgrid-scale
	1982	turbulent kinetic energy difference used as
[5]	1983	criterion for applying the upstream scheme when upstream-spline
	1984	advection is switched on (in m<sup>2</sup>/s<sup>2</sup>).
[61]	1985	</p> <p>This variable steers the appropriate
	1986	treatment of the
[5]	1987	advection of the subgrid-scale turbulent kinetic energy in case that
	1988	the uptream-spline scheme is used . For further information see <a href="#ups_limit_pt">ups_limit_pt</a>.  </p>
[61]	1989	<p>Only positive values are allowed for <b>ups_limit_e</b>.
	1990	</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_pt"></a><b>ups_limit_pt</b></p>
	1991	</td> <td style="vertical-align: top;">R</td>
	1992	<td style="vertical-align: top;"><i>0.0</i></td>
	1993	<td style="vertical-align: top;"> <p>Temperature
	1994	difference used as criterion for applying
	1995	the upstream scheme when upstream-spline advection  is
	1996	switched on
	1997	(in K).  </p> <p>This criterion is used if the
	1998	upstream-spline scheme is
[5]	1999	switched on (see <a href="#scalar_advec">scalar_advec</a>).<br>
	2000	If, for a given gridpoint, the absolute temperature difference with
	2001	respect to the upstream
	2002	grid point is smaller than the value given for <b>ups_limit_pt</b>,
	2003	the upstream scheme is used for this gridpoint (by default, the
	2004	upstream-spline scheme is always used). Reason: in case of a very small
	2005	upstream gradient, the advection should cause only a very small
	2006	tendency. However, in such situations the upstream-spline scheme may
	2007	give wrong tendencies at a
	2008	grid point due to spline overshooting, if simultaneously the downstream
	2009	gradient is very large. In such cases it may be more reasonable to use
	2010	the upstream scheme. The numerical diffusion caused by the upstream
	2011	schme remains small as long as the upstream gradients are small.<br>
[61]	2012	</p> <p>The percentage of grid points for which the
	2013	upstream
[5]	2014	scheme is actually used, can be output as a time series with respect to
	2015	the
[61]	2016	three directions in space with run parameter (see <a href="chapter_4.2.html#dt_dots">dt_dots</a>, the
	2017	timeseries names in the NetCDF file are <i>'splptx'</i>, <i>'splpty'</i>,
	2018	<i>'splptz'</i>). The percentage
	2019	of gridpoints  should stay below a certain limit, however, it
	2020	is
[5]	2021	not possible to give
	2022	a general limit, since it depends on the respective flow.  </p>
[61]	2023	<p>Only positive values are permitted for <b>ups_limit_pt</b>.<br>
	2024	</p>
[5]	2025	A more effective control of
[61]	2026	the “overshoots” can be achieved with parameter <a href="#cut_spline_overshoot">cut_spline_overshoot</a>.
	2027	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_u"></a><b>ups_limit_u</b></p>
	2028	</td> <td style="vertical-align: top;">R</td>
	2029	<td style="vertical-align: top;"><i>0.0</i></td>
	2030	<td style="vertical-align: top;"> <p>Velocity
	2031	difference (u-component) used as criterion for
[5]	2032	applying the upstream scheme
	2033	when upstream-spline advection is switched on (in m/s).  </p>
[61]	2034	<p>This variable steers the appropriate treatment of the
[5]	2035	advection of the u-velocity-component in case that the upstream-spline
	2036	scheme is used. For further
[61]	2037	information see <a href="#ups_limit_pt">ups_limit_pt</a>.
	2038	</p> <p>Only positive values are permitted for <b>ups_limit_u</b>.</p>
	2039	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_v"></a><b>ups_limit_v</b></p>
	2040	</td> <td style="vertical-align: top;">R</td>
	2041	<td style="vertical-align: top;"><i>0.0</i></td>
	2042	<td style="vertical-align: top;"> <p>Velocity
	2043	difference (v-component) used as criterion for
[5]	2044	applying the upstream scheme
	2045	when upstream-spline advection is switched on (in m/s).  </p>
[61]	2046	<p>This variable steers the appropriate treatment of the
[5]	2047	advection of the v-velocity-component in case that the upstream-spline
	2048	scheme is used. For further
[61]	2049	information see <a href="#ups_limit_pt">ups_limit_pt</a>.
	2050	</p> <p>Only positive values are permitted for <b>ups_limit_v</b>.</p>
	2051	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_w"></a><b>ups_limit_w</b></p>
	2052	</td> <td style="vertical-align: top;">R</td>
	2053	<td style="vertical-align: top;"><i>0.0</i></td>
	2054	<td style="vertical-align: top;"> <p>Velocity
	2055	difference (w-component) used as criterion for
[5]	2056	applying the upstream scheme
	2057	when upstream-spline advection is switched on (in m/s).  </p>
[61]	2058	<p>This variable steers the appropriate treatment of the
[5]	2059	advection of the w-velocity-component in case that the upstream-spline
	2060	scheme is used. For further
[61]	2061	information see <a href="#ups_limit_pt">ups_limit_pt</a>.
	2062	</p> <p>Only positive values are permitted for <b>ups_limit_w</b>.</p>
	2063	</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="use_surface_fluxes"></a><b>use_surface_fluxes</b></p>
	2064	</td> <td style="vertical-align: top;">L</td>
	2065	<td style="vertical-align: top;"><i>.F.</i></td>
	2066	<td style="vertical-align: top;"> <p>Parameter to
	2067	steer the treatment of the subgrid-scale vertical
	2068	fluxes within the diffusion terms at k=1 (bottom boundary).<br> </p>
	2069	<p>By default, the near-surface subgrid-scale fluxes are
[5]	2070	parameterized (like in the remaining model domain) using the gradient
	2071	approach. If <b>use_surface_fluxes</b>
[61]	2072	= <i>.TRUE.</i>, the user-assigned surface fluxes are used
	2073	instead
	2074	(see <a href="#surface_heatflux">surface_heatflux</a>,
	2075	<a href="#surface_waterflux">surface_waterflux</a>
	2076	and <a href="#surface_scalarflux">surface_scalarflux</a>)
	2077	<span style="font-weight: bold;">or</span> the
	2078	surface fluxes are
[5]	2079	calculated via the Prandtl layer relation (depends on the bottom
[61]	2080	boundary conditions, see <a href="#bc_pt_b">bc_pt_b</a>,
	2081	<a href="#bc_q_b">bc_q_b</a>
	2082	and <a href="#bc_s_b">bc_s_b</a>).<br> </p>
	2083	<p><b>use_surface_fluxes</b>
	2084	is automatically set <i>.TRUE.</i>, if a Prandtl layer is
	2085	used (see <a href="#prandtl_layer">prandtl_layer</a>).
	2086	</p> <p>The user may prescribe the surface fluxes at the
	2087	bottom
	2088	boundary without using a Prandtl layer by setting <span style="font-weight: bold;">use_surface_fluxes</span> =
	2089	<span style="font-style: italic;">.T.</span> and <span style="font-weight: bold;">prandtl_layer</span> = <span style="font-style: italic;">.F.</span>. If , in this
	2090	case, the
	2091	momentum flux (u<sub>*</sub><sup>2</sup>)
	2092	should also be prescribed,
[5]	2093	the user must assign an appropriate value within the user-defined code.</p>
[61]	2094	</td> </tr> <tr><td style="vertical-align: top;"><a name="use_top_fluxes"></a><span style="font-weight: bold;">use_top_fluxes</span></td><td style="vertical-align: top;">L</td><td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td><td style="vertical-align: top;"> <p>Parameter to steer
	2095	the treatment of the subgrid-scale vertical
	2096	fluxes within the diffusion terms at k=nz (top boundary).</p><p>By
	2097	default, the fluxes at nz are calculated using the gradient approach.
	2098	If <b>use_top_fluxes</b>
	2099	= <i>.TRUE.</i>, the user-assigned top fluxes are used
	2100	instead
[103]	2101	(see <a href="chapter_4.1.html#top_heatflux">top_heatflux</a>, <a href="#top_momentumflux_u">top_momentumflux_u</a>, <a href="#top_momentumflux_v">top_momentumflux_v</a>, <a href="#top_salinityflux">top_salinityflux</a>).</p><p>Currently, no value for the latent heatflux can be assigned. In case of <span style="font-weight: bold;">use_top_fluxes</span> = <span style="font-style: italic;">.TRUE.</span>, the latent
[61]	2102	heat flux at the top will be automatically set to zero.</p></td></tr><tr>
	2103	<td style="vertical-align: top;"> <p><a name="use_ug_for_galilei_tr"></a><b>use_ug_for_galilei_tr</b></p>
	2104	</td> <td style="vertical-align: top;">L</td>
	2105	<td style="vertical-align: top;"><i>.T.</i></td>
	2106	<td style="vertical-align: top;"> <p>Switch to
	2107	determine the translation velocity in case that a
	2108	Galilean transformation is used.<br> </p> <p>In
	2109	case of a Galilean transformation (see <a href="#galilei_transformation">galilei_transformation</a>),
	2110	<b>use_ug_for_galilei_tr</b>
[5]	2111	= <i>.T.</i>  ensures
	2112	that the coordinate system is translated with the geostrophic windspeed.<br>
[61]	2113	</p> <p>Alternatively, with <b>use_ug_for_galilei_tr</b>
	2114	= <i>.F</i>.,
[5]	2115	the
	2116	geostrophic wind can be replaced as translation speed by the (volume)
	2117	averaged velocity. However, in this case the user must be aware of fast
	2118	growing gravity waves, so this
[61]	2119	choice is usually not recommended!</p> </td> </tr> <tr><td align="left" valign="top"><a name="use_upstream_for_tke"></a><span style="font-weight: bold;">use_upstream_for_tke</span></td><td align="left" valign="top">L</td><td align="left" valign="top"><span style="font-style: italic;">.F.</span></td><td align="left" valign="top">Parameter to choose the
	2120	advection/timestep scheme to be used for the subgrid-scale TKE.<br><br>By
[5]	2121	default, the advection scheme and the timestep scheme to be used for
[61]	2122	the subgrid-scale TKE are set by the initialization parameters <a href="#scalar_advec">scalar_advec</a> and <a href="#timestep_scheme">timestep_scheme</a>,
	2123	respectively. <span style="font-weight: bold;">use_upstream_for_tke</span>
	2124	= <span style="font-style: italic;">.T.</span>
[5]	2125	forces the Euler-scheme and the upstream-scheme to be used as timestep
	2126	scheme and advection scheme, respectively. By these methods, the strong
	2127	(artificial) near-surface vertical gradients of the subgrid-scale TKE
	2128	are significantly reduced. This is required when subgrid-scale
	2129	velocities are used for advection of particles (see particle package
	2130	parameter <a href="chapter_4.2.html#use_sgs_for_particles">use_sgs_for_particles</a>).</td></tr><tr>
[61]	2131	<td style="vertical-align: top;"> <p><a name="vg_surface"></a><span style="font-weight: bold;">vg_surface</span></p>
	2132	</td> <td style="vertical-align: top;">R<br> </td>
	2133	<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
	2134	<td style="vertical-align: top;">v-component of the
	2135	geostrophic
	2136	wind at the surface (in m/s).<br> <br>
[5]	2137	This parameter assigns the value of the v-component of the geostrophic
	2138	wind (vg) at the surface (k=0). Starting from this value, the initial
	2139	vertical profile of the <br>
[61]	2140	v-component of the geostrophic wind is constructed with <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
	2141	and <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
	2142	The
[5]	2143	profile
	2144	constructed in that way is used for creating the initial vertical
	2145	velocity profile of the 3d-model. Either it is applied, as it has been
	2146	specified by the user (<a href="#initializing_actions">initializing_actions</a>
	2147	= 'set_constant_profiles')
	2148	or it is used for calculating a stationary boundary layer wind profile
[61]	2149	(<a href="#initializing_actions">initializing_actions</a>
	2150	=
[5]	2151	'set_1d-model_profiles'). If vg is constant
	2152	with height (i.e. vg(k)=<span style="font-weight: bold;">vg_surface</span>)
	2153	and  has a large value, it is
	2154	recommended to use a Galilei-transformation of the coordinate system,
	2155	if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
	2156	in order to obtain larger
[97]	2157	time steps.<br><br><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>),
	2158	this parameter gives the velocity value at the sea surface, which is
	2159	at k=nzt. The profile is then constructed from the surface down to the
	2160	bottom of the model.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="vg_vertical_gradient"></a><span style="font-weight: bold;">vg_vertical_gradient</span></p>
[61]	2161	</td> <td style="vertical-align: top;">R(10)<br>
	2162	</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
	2163	* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
	2164	profile of the  v-component of the geostrophic wind (in
	2165	1/100s).<br> <br>
[5]	2166	The gradient holds starting from the height level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>
	2167	(precisely: for all uv levels k where zu(k)
	2168	> <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
	2169	vg(k) is set: vg(k) = vg(k-1) + dzu(k)
[61]	2170	* <span style="font-weight: bold;">vg_vertical_gradient</span>)
	2171	up to
[5]	2172	the top boundary or up to the next height
	2173	level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
	2174	A total of 10 different
[61]	2175	gradients for 11 height intervals (10 intervals  if <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>(1)
	2176	=
[5]	2177	0.0) can be assigned. The surface
[97]	2178	geostrophic wind is assigned by <a href="#vg_surface">vg_surface</a>.<br><br><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>),
	2179	the profile is constructed like described above, but starting from the
	2180	sea surface (k=nzt) down to the bottom boundary of the model. Height
	2181	levels have then to be given as negative values, e.g. <span style="font-weight: bold;">vg_vertical_gradient_level</span> = <span style="font-style: italic;">-500.0</span>, <span style="font-style: italic;">-1000.0</span>.</td>
[61]	2182	</tr> <tr> <td style="vertical-align: top;">
	2183	<p><a name="vg_vertical_gradient_level"></a><span style="font-weight: bold;">vg_vertical_gradient_level</span></p>
	2184	</td> <td style="vertical-align: top;">R(10)<br>
	2185	</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
	2186	* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
[5]	2187	gradient defined by <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
[61]	2188	is effective (in m).<br> <br>
[97]	2189	The height levels have to be assigned in ascending order. For the
[5]	2190	piecewise construction of a profile of the v-component of the
[97]	2191	geostrophic wind component (vg) see <a href="#vg_vertical_gradient">vg_vertical_gradient</a>.<br><br><span style="font-weight: bold;">Attention:</span><br>In case of ocean runs (see <a href="chapter_4.1.html#ocean">ocean</a>), the (negative) height levels have to be assigned in descending order.</td>
[61]	2192	</tr> <tr> <td style="vertical-align: top;">
	2193	<p><a name="wall_adjustment"></a><b>wall_adjustment</b></p>
	2194	</td> <td style="vertical-align: top;">L</td>
	2195	<td style="vertical-align: top;"><i>.T.</i></td>
	2196	<td style="vertical-align: top;"> <p>Parameter to
	2197	restrict the mixing length in the vicinity of the
[5]	2198	bottom
[61]	2199	boundary.  </p> <p>With <b>wall_adjustment</b>
	2200	= <i>.TRUE., </i>the mixing
[5]	2201	length is limited to a maximum of  1.8 * z. This condition
	2202	typically affects only the
[61]	2203	first grid points above the bottom boundary.</p> </td> </tr>
	2204	<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="wall_heatflux"></a>wall_heatflux</span></td>
	2205	<td style="vertical-align: top;">R(5)</td> <td style="vertical-align: top;"><span style="font-style: italic;">5 * 0.0</span></td> <td>Prescribed
	2206	kinematic sensible heat flux in W m<sup>-2</sup>
	2207	at the five topography faces:<br> <br> <div style="margin-left: 40px;"><span style="font-weight: bold;">wall_heatflux(0)
	2208	</span>top face<br> <span style="font-weight: bold;">wall_heatflux(1)
	2209	</span>left face<br> <span style="font-weight: bold;">wall_heatflux(2)
	2210	</span>right face<br> <span style="font-weight: bold;">wall_heatflux(3)
	2211	</span>south face<br> <span style="font-weight: bold;">wall_heatflux(4)
	2212	</span>north face</div> <br>
	2213	This parameter applies only in case of a non-flat <a href="#topography">topography</a>. The
	2214	parameter <a href="#random_heatflux">random_heatflux</a>
	2215	can be used to impose random perturbations on the internal
	2216	two-dimensional surface heat
	2217	flux field <span style="font-style: italic;">shf</span>
	2218	that is composed of <a href="#surface_heatflux">surface_heatflux</a>
	2219	at the bottom surface and <span style="font-weight: bold;">wall_heatflux(0)</span>
	2220	at the topography top face. </td> </tr> </tbody>
	2221	</table><br>
	2222	<p style="line-height: 100%;"><br><font color="#000080"><font color="#000080"><a href="chapter_4.0.html"><font color="#000080"><img name="Grafik1" src="left.gif" align="bottom" border="2" height="32" width="32"></font></a><a href="index.html"><font color="#000080"><img name="Grafik2" src="up.gif" align="bottom" border="2" height="32" width="32"></font></a><a href="chapter_4.2.html"><font color="#000080"><img name="Grafik3" src="right.gif" align="bottom" border="2" height="32" width="32"></font></a></font></font></p>
	2223	<p style="line-height: 100%;"><i>Last
	2224	change: </i> $Id: chapter_4.1.html 103 2007-07-30 10:49:46Z raasch $ </p>
	2225	<br><br>
[5]	2226	</body></html>

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