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1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
3<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"><title>PALM chapter 4.1</title></head>
4<body><h3><a name="chapter4.1"></a>4.1
5Initialization 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
15mixing length to the Prandtl-layer law.&nbsp; </p> <p>Usually
16the mixing length in LES models l<sub>LES</sub>
17depends (as in PALM) on the grid size and is possibly restricted
18further in case of stable stratification and near the lower wall (see
19parameter <a href="#wall_adjustment">wall_adjustment</a>).
20With <b>adjust_mixing_length</b> = <span style="font-style: italic;">.T.</span>
21the Prandtl' mixing length l<sub>PR</sub> = kappa * z/phi
22is calculated
23and the mixing length actually used in the model is set l = MIN (l<sub>LES</sub>,
24l<sub>PR</sub>). This usually gives a decrease of the
25mixing length at
26the bottom boundary and considers the fact that eddy sizes
27decrease in the vicinity of the wall.&nbsp; </p> <p style="font-style: normal;"><b>Warning:</b> So
28far, there is
29no good experience with <b>adjust_mixing_length</b> = <span style="font-style: italic;">.T.</span> !&nbsp; </p>
30<p>With <b>adjust_mixing_length</b> = <span style="font-style: italic;">.T.</span> and the
31Prandtl-layer being
32switched on (see <a href="#prandtl_layer">prandtl_layer</a>)
33<span style="font-style: italic;">'(u*)** 2+neumann'</span>
34should always be set as the lower boundary condition for the TKE (see <a href="#bc_e_b">bc_e_b</a>),
35otherwise the near-surface value of the TKE is not in agreement with
36the Prandtl-layer law (Prandtl-layer law and Prandtl-Kolmogorov-Ansatz
37should provide the same value for K<sub>m</sub>). A warning
38is given,
39if 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
44with respect to the horizontal (in degrees).&nbsp; </p> <p style="font-style: normal;">By means of <b>alpha_surface</b>
45the model domain can be inclined in x-direction with respect to the
46horizontal. In this way flows over inclined surfaces (e.g. drainage
47flows, gravity flows) can be simulated. In case of <b>alpha_surface
48</b>/= <span style="font-style: italic;">0</span>
49the buoyancy term
50appears both in
51the equation of motion of the u-component and of the w-component.<br>
52</p> <p style="font-style: normal;">An inclination
53is only possible in
54case of cyclic horizontal boundary conditions along x AND y (see <a href="#bc_lr">bc_lr</a>
55and <a href="#bc_ns">bc_ns</a>) and <a href="#topography">topography</a> = <span style="font-style: italic;">'flat'</span>. </p>
56<p>Runs with inclined surface still require additional
57user-defined code as well as modifications to the default code. Please
58ask the <a href="">PALM
59developer&nbsp; 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
63TKE.&nbsp; </p> <p><b>bc_e_b</b> may be
64set to&nbsp;<span style="font-style: italic;">'neumann'</span>
65or <span style="font-style: italic;">'(u*) ** 2+neumann'</span>.
67= <span style="font-style: italic;">'neumann'</span>
68yields to
69e(k=0)=e(k=1) (Neumann boundary condition), where e(k=1) is calculated
70via the prognostic TKE equation. Choice of <span style="font-style: italic;">'(u*)**2+neumann'</span>
71also yields to
72e(k=0)=e(k=1), but the TKE at the Prandtl-layer top (k=1) is calculated
73diagnostically by e(k=1)=(us/0.1)**2. However, this is only allowed if
74a Prandtl-layer is used (<a href="#prandtl_layer">prandtl_layer</a>).
75If this is not the case, a warning is given and <b>bc_e_b</b>
76is reset
77to <span style="font-style: italic;">'neumann'</span>.&nbsp;
78</p> <p style="font-style: normal;">At the top
79boundary a Neumann
80boundary 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
86condition along x (for all quantities).<br> <br>
87By default, a cyclic boundary condition is used along x.<br> <br>
88<span style="font-weight: bold;">bc_lr</span> may
89also be
90assigned the values <span style="font-style: italic;">'dirichlet/neumann'</span>
91(inflow from left, outflow to the right) or <span style="font-style: italic;">'neumann/dirichlet'</span>
92(inflow from
93right, outflow to the left). This requires the multi-grid method to be
94used for solving the Poisson equation for perturbation pressure (see <a href="">psolver</a>)
95and it also requires cyclic boundary conditions along y (see<br> <a href="#bc_ns">bc_ns</a>).<br> <br>
96In case of these non-cyclic lateral boundaries, a Dirichlet condition
97is used at the inflow for all quantities (initial vertical profiles -
98see <a href="#initializing_actions">initializing_actions</a>
99- are fixed during the run) except u, to which a Neumann (zero
100gradient) condition is applied. At the outflow, a Neumann (zero
101gradient) condition is used for all quantities except v, which is set
102to its horizontal average along the outflow (e.g. v(k,:,nx+1) =
103average_along_y( v(k,:,nx)), and except w, which is set to zero
104(Dirichlet condition). These conditions ensure the velocity field to be
105free of divergence at the inflow and at the outflow. For perturbation
106pressure Neumann (zero gradient) conditions are assumed both at the
107inflow and at the outflow.<br> <br>
108When using non-cyclic lateral boundaries, a filter is applied to the
109velocity field in the vicinity of the outflow in order to suppress any
110reflections of outgoing disturbances (see <a href="#km_damp_max">km_damp_max</a>
111and <a href="#outflow_damping_width">outflow_damping_width</a>).<br>
113In order to maintain a turbulent state of the flow, it may be
114neccessary to continuously impose perturbations on the horizontal
115velocity field in the vicinity of the inflow throughout the whole run.
116This can be switched on using <a href="">create_disturbances</a>.
117The horizontal range to which these perturbations are applied is
118controlled by the parameters <a href="#inflow_disturbance_begin">inflow_disturbance_begin</a>
119and <a href="#inflow_disturbance_end">inflow_disturbance_end</a>.
120The vertical range and the perturbation amplitude are given by <a href="">disturbance_level_b</a>,
121<a href="">disturbance_level_t</a>,
122and <a href="">disturbance_amplitude</a>.
123The time interval at which perturbations are to be imposed is set by <a href="">dt_disturb</a>.<br>
125In case of non-cyclic horizontal boundaries <a href="">call_psolver
126at_all_substeps</a> = .T. should be used.<br> <br> <span style="font-weight: bold;">Note:</span><br>
127Using non-cyclic lateral boundaries requires very sensitive adjustments
128of the inflow (vertical profiles) and the bottom boundary conditions,
129e.g. a surface heating should not be applied near the inflow boundary
130because this may significantly disturb the inflow. Please check the
131model results very carefully.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_ns"></a><b>bc_ns</b></p>
132</td> <td style="vertical-align: top;">C * 20</td>
133<td style="vertical-align: top;"><span style="font-style: italic;">'cyclic'</span></td>
134<td style="vertical-align: top;">Boundary
135condition along y (for all quantities).<br> <br>
136By default, a cyclic boundary condition is used along y.<br> <br>
137<span style="font-weight: bold;">bc_ns</span> may
138also be
139assigned the values <span style="font-style: italic;">'dirichlet/neumann'</span>
140(inflow from rear ("north"), outflow to the front ("south")) or <span style="font-style: italic;">'neumann/dirichlet'</span>
141(inflow from front ("south"), outflow to the rear ("north")). This
142requires the multi-grid
143method to be used for solving the Poisson equation for perturbation
144pressure (see <a href="chapter_4.2.html#psolver">psolver</a>)
145and it also requires cyclic boundary conditions along x (see<br> <a href="#bc_lr">bc_lr</a>).<br> <br>
146In case of these non-cyclic lateral boundaries, a Dirichlet condition
147is used at the inflow for all quantities (initial vertical profiles -
148see <a href="#initializing_actions">initializing_actions</a>
149- are fixed during the run) except v, to which a Neumann (zero
150gradient) condition is applied. At the outflow, a Neumann (zero
151gradient) condition is used for all quantities except u, which is set
152to its horizontal average along the outflow (e.g. u(k,ny+1,:) =
153average_along_x( u(k,ny,:)), and except w, which is set to zero
154(Dirichlet condition). These conditions ensure the velocity field to be
155free of divergence at the inflow and at the outflow. For perturbation
156pressure Neumann (zero gradient) conditions are assumed both at the
157inflow and at the outflow.<br> <br>
158For further details regarding non-cyclic lateral boundary conditions
159see <a href="#bc_lr">bc_lr</a>.</td> </tr>
160<tr> <td style="vertical-align: top;"> <p><a name="bc_p_b"></a><b>bc_p_b</b></p> </td>
161<td style="vertical-align: top;">C * 20</td> <td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
162<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
163perturbation pressure.&nbsp; </p> <p>Allowed values
164are <span style="font-style: italic;">'dirichlet'</span>,
165<span style="font-style: italic;">'neumann'</span>
166and <span style="font-style: italic;">'neumann+inhomo'</span>.&nbsp;
167<span style="font-style: italic;">'dirichlet'</span>
169p(k=0)=0.0,&nbsp; <span style="font-style: italic;">'neumann'</span>
170sets p(k=0)=p(k=1). <span style="font-style: italic;">'neumann+inhomo'</span>
171corresponds to an extended Neumann boundary condition where heat flux
172or temperature inhomogeneities near the
173surface (pt(k=1))&nbsp; are additionally regarded (see Shen and
175(1995, Q.J.R. Meteorol. Soc.,
1761209)). This condition is only permitted with the Prandtl-layer
177switched on (<a href="#prandtl_layer">prandtl_layer</a>),
178otherwise the run is terminated.&nbsp; </p> <p>Since
179at the bottom boundary of the model the vertical
181disappears (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>)
182dp/dz = 0 should
183be used, which leaves the vertical component w unchanged when the
184pressure solver is applied. Simultaneous use of the Neumann boundary
185conditions both at the bottom and at the top boundary (<a href="#bc_p_t">bc_p_t</a>)
186usually yields no consistent solution for the perturbation pressure and
187should be avoided.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_p_t"></a><b>bc_p_t</b></p>
188</td> <td style="vertical-align: top;">C * 20</td>
189<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
190<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
191perturbation pressure.&nbsp; </p> <p style="font-style: normal;">Allowed values are <span style="font-style: italic;">'dirichlet'</span>
192(p(k=nz+1)= 0.0) or <span style="font-style: italic;">'neumann'</span>
193(p(k=nz+1)=p(k=nz)).&nbsp; </p> <p>Simultaneous use
194of Neumann boundary conditions both at the
195top and bottom boundary (<a href="#bc_p_b">bc_p_b</a>)
196usually yields no consistent solution for the perturbation pressure and
197should be avoided. Since at the bottom boundary the Neumann
198condition&nbsp; is a good choice (see <a href="#bc_p_b">bc_p_b</a>),
199a Dirichlet condition should be set at the top boundary.</p> </td>
200</tr> <tr> <td style="vertical-align: top;">
201<p><a name="bc_pt_b"></a><b>bc_pt_b</b></p>
202</td> <td style="vertical-align: top;">C*20</td>
203<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
204<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
205potential temperature.&nbsp; </p> <p>Allowed values
206are <span style="font-style: italic;">'dirichlet'</span>
207(pt(k=0) = const. = <a href="#pt_surface">pt_surface</a>
208+ <a href="#pt_surface_initial_change">pt_surface_initial_change</a>;
209the user may change this value during the run using user-defined code)
210and <span style="font-style: italic;">'neumann'</span>
211(pt(k=0)=pt(k=1)).&nbsp; <br>
212When a constant surface sensible heat flux is used (<a href="#surface_heatflux">surface_heatflux</a>), <b>bc_pt_b</b>
213= <span style="font-style: italic;">'neumann'</span>
214must be used, because otherwise the resolved scale may contribute to
215the surface flux so that a constant value cannot be guaranteed.</p>
216</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pc_pt_t"></a><b>bc_pt_t</b></p>
217</td> <td style="vertical-align: top;">C * 20</td>
218<td style="vertical-align: top;"><span style="font-style: italic;">'initial gradient'</span></td>
219<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
220potential temperature.&nbsp; </p> <p>Allowed are the
221values <span style="font-style: italic;">'dirichlet' </span>(pt(k=nz+1)
222does not change during the run), <span style="font-style: italic;">'neumann'</span>
223(pt(k=nz+1)=pt(k=nz)), and <span style="font-style: italic;">'initial_gradient'</span>.
224With the 'initial_gradient'-condition the value of the temperature
225gradient at the top is
226calculated from the initial
227temperature profile (see <a href="#pt_surface">pt_surface</a>,
228<a href="#pt_vertical_gradient">pt_vertical_gradient</a>)
229by bc_pt_t_val = (pt_init(k=nz+1) -
230pt_init(k=nz)) / dzu(nz+1).<br>
231Using this value (assumed constant during the
232run) the temperature boundary values are calculated as&nbsp; </p>
233<ul> <p style="font-style: normal;">pt(k=nz+1) =
234pt(k=nz) +
235bc_pt_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up to k=nz the prognostic
236equation for the temperature is solved).<br>
237When a constant sensible heat flux is used at the top boundary (<a href="chapter_4.1.html#top_heatflux">top_heatflux</a>),
238<b>bc_pt_t</b> = <span style="font-style: italic;">'neumann'</span>
239must be used, because otherwise the resolved scale may contribute to
240the top flux so that a constant value cannot be guaranteed.</p> </td>
241</tr> <tr> <td style="vertical-align: top;">
242<p><a name="bc_q_b"></a><b>bc_q_b</b></p>
243</td> <td style="vertical-align: top;">C * 20</td>
244<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
245<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
246specific humidity / total water content.&nbsp; </p> <p>Allowed
247values are <span style="font-style: italic;">'dirichlet'</span>
248(q(k=0) = const. = <a href="#q_surface">q_surface</a>
249+ <a href="#q_surface_initial_change">q_surface_initial_change</a>;
250the user may change this value during the run using user-defined code)
251and <span style="font-style: italic;">'neumann'</span>
252(q(k=0)=q(k=1)).&nbsp; <br>
253When a constant surface latent heat flux is used (<a href="#surface_waterflux">surface_waterflux</a>), <b>bc_q_b</b>
254= <span style="font-style: italic;">'neumann'</span>
255must be used, because otherwise the resolved scale may contribute to
256the surface flux so that a constant value cannot be guaranteed.</p>
257</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_q_t"></a><b>bc_q_t</b></p>
258</td> <td style="vertical-align: top;"><span style="font-style: italic;">C
259* 20</span></td> <td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
260<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
261specific humidity / total water content.&nbsp; </p> <p>Allowed
262are the values <span style="font-style: italic;">'dirichlet'</span>
263(q(k=nz) and q(k=nz+1) do
264not change during the run) and <span style="font-style: italic;">'neumann'</span>.
265With the Neumann boundary
266condition the value of the humidity gradient at the top is calculated
267from the
268initial humidity profile (see <a href="#q_surface">q_surface</a>,
269<a href="#q_vertical_gradient">q_vertical_gradient</a>)
270by: bc_q_t_val = ( q_init(k=nz) - q_init(k=nz-1)) / dzu(nz).<br>
271Using this value (assumed constant during the run) the humidity
272boundary values
273are calculated as&nbsp; </p> <ul> <p style="font-style: normal;">q(k=nz+1) =q(k=nz) +
274bc_q_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up tp k=nz the prognostic
275equation for q is solved). </p> </td> </tr> <tr>
276<td style="vertical-align: top;"> <p><a name="bc_s_b"></a><b>bc_s_b</b></p> </td>
277<td style="vertical-align: top;">C * 20</td> <td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
278<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
279scalar concentration.&nbsp; </p> <p>Allowed values
280are <span style="font-style: italic;">'dirichlet'</span>
281(s(k=0) = const. = <a href="#s_surface">s_surface</a>
282+ <a href="#s_surface_initial_change">s_surface_initial_change</a>;
283the user may change this value during the run using user-defined code)
284and <span style="font-style: italic;">'neumann'</span>
285(s(k=0) =
286s(k=1)).&nbsp; <br>
287When a constant surface concentration flux is used (<a href="#surface_scalarflux">surface_scalarflux</a>), <b>bc_s_b</b>
288= <span style="font-style: italic;">'neumann'</span>
289must be used, because otherwise the resolved scale may contribute to
290the surface flux so that a constant value cannot be guaranteed.</p>
291</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_s_t"></a><b>bc_s_t</b></p>
292</td> <td style="vertical-align: top;">C * 20</td>
293<td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
294<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
295scalar concentration.&nbsp; </p> <p>Allowed are the
296values <span style="font-style: italic;">'dirichlet'</span>
297(s(k=nz) and s(k=nz+1) do
298not change during the run) and <span style="font-style: italic;">'neumann'</span>.
299With the Neumann boundary
300condition the value of the scalar concentration gradient at the top is
302from the initial scalar concentration profile (see <a href="#s_surface">s_surface</a>, <a href="#s_vertical_gradient">s_vertical_gradient</a>)
303by: bc_s_t_val = (s_init(k=nz) - s_init(k=nz-1)) / dzu(nz).<br>
304Using this value (assumed constant during the run) the concentration
305boundary values
306are calculated as </p> <ul> <p style="font-style: normal;">s(k=nz+1) = s(k=nz) +
307bc_s_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up to k=nz the prognostic
308equation for the scalar concentration is
309solved).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_uv_b"></a><b>bc_uv_b</b></p>
310</td> <td style="vertical-align: top;">C * 20</td>
311<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
312<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
313horizontal velocity components u and v.&nbsp; </p> <p>Allowed
314values are <span style="font-style: italic;">'dirichlet' </span>and
315<span style="font-style: italic;">'neumann'</span>. <b>bc_uv_b</b>
316= <span style="font-style: italic;">'dirichlet'</span>
317yields the
318no-slip condition with u=v=0 at the bottom. Due to the staggered grid
319u(k=0) and v(k=0) are located at z = - 0,5 * <a href="#dz">dz</a>
320(below the bottom), while u(k=1) and v(k=1) are located at z = +0,5 *
321dz. u=v=0 at the bottom is guaranteed using mirror boundary
322condition:&nbsp; </p> <ul> <p style="font-style: normal;">u(k=0) = - u(k=1) and v(k=0) = -
323v(k=1)</p> </ul> <p style="font-style: normal;">The
324Neumann boundary condition
325yields the free-slip condition with u(k=0) = u(k=1) and v(k=0) =
327With Prandtl - layer switched on, the free-slip condition is not
328allowed (otherwise the run will be terminated)<font color="#000000">.</font></p>
329</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_uv_t"></a><b>bc_uv_t</b></p>
330</td> <td style="vertical-align: top;">C * 20</td>
331<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
332<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
333horizontal velocity components u and v.&nbsp; </p> <p>Allowed
334values are <span style="font-style: italic;">'dirichlet'</span>
335and <span style="font-style: italic;">'neumann'</span>.
337Dirichlet condition yields u(k=nz+1) = ug(nz+1) and v(k=nz+1) =
339Neumann condition yields the free-slip condition with u(k=nz+1) =
340u(k=nz) and v(k=nz+1) = v(k=nz) (up to k=nz the prognostic equations
341for the velocities are solved).</p> </td> </tr> <tr>
342<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_height"></a>building_height</span></td>
343<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">50.0</span></td> <td>Height
344of a single building in m.<br> <br> <span style="font-weight: bold;">building_height</span> must
345be less than the height of the model domain. This parameter requires
346the use of&nbsp;<a href="#topography">topography</a>
347= <span style="font-style: italic;">'single_building'</span>.</td>
348</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_length_x"></a>building_length_x</span></td>
349<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
350building in m.<br> <br>
351Currently, <span style="font-weight: bold;">building_length_x</span>
352must be at least <span style="font-style: italic;">3
353*&nbsp;</span><a style="font-style: italic;" href="#dx">dx</a> and no more than <span style="font-style: italic;">(&nbsp;</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>
354</span><span style="font-style: italic;">- <a href="#building_wall_left">building_wall_left</a></span>.
355This parameter requires the use of&nbsp;<a href="#topography">topography</a>
356= <span style="font-style: italic;">'single_building'</span>.</td>
357</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_length_y"></a>building_length_y</span></td>
358<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">50.0</span></td> <td>Depth
359of a single building in m.<br> <br>
360Currently, <span style="font-weight: bold;">building_length_y</span>
361must be at least <span style="font-style: italic;">3
362*&nbsp;</span><a style="font-style: italic;" href="#dy">dy</a> and no more than <span style="font-style: italic;">(&nbsp;</span><a style="font-style: italic;" href="#ny">ny</a><span style="font-style: italic;"> - 1 )&nbsp;</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
363the use of&nbsp;<a href="#topography">topography</a>
364= <span style="font-style: italic;">'single_building'</span>.</td>
365</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_wall_left"></a>building_wall_left</span></td>
366<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">building centered in x-direction</span></td>
367<td>x-coordinate of the left building wall (distance between the
368left building wall and the left border of the model domain) in m.<br>
370Currently, <span style="font-weight: bold;">building_wall_left</span>
371must be at least <span style="font-style: italic;">1
372*&nbsp;</span><a style="font-style: italic;" href="#dx">dx</a> and less than <span style="font-style: italic;">( <a href="#nx">nx</a>&nbsp;
373- 1 ) * <a href="#dx">dx</a> -&nbsp; <a href="#building_length_x">building_length_x</a></span>.
374This parameter requires the use of&nbsp;<a href="#topography">topography</a>
375= <span style="font-style: italic;">'single_building'</span>.<br>
377The default value&nbsp;<span style="font-weight: bold;">building_wall_left</span>
378= <span style="font-style: italic;">( ( <a href="#nx">nx</a>&nbsp;+
3791 ) * <a href="#dx">dx</a> -&nbsp; <a href="#building_length_x">building_length_x</a> ) / 2</span>
380centers the building in x-direction. </td> </tr> <tr>
381<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_wall_south"></a>building_wall_south</span></td>
382<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>
383<td>y-coordinate of the South building wall (distance between the
384South building wall and the South border of the model domain) in m.<br>
386Currently, <span style="font-weight: bold;">building_wall_south</span>
387must be at least <span style="font-style: italic;">1
388*&nbsp;</span><a style="font-style: italic;" href="#dy">dy</a> and less than <span style="font-style: italic;">( <a href="#ny">ny</a>&nbsp;
389- 1 ) * <a href="#dy">dy</a> -&nbsp; <a href="#building_length_y">building_length_y</a></span>.
390This parameter requires the use of&nbsp;<a href="#topography">topography</a>
391= <span style="font-style: italic;">'single_building'</span>.<br>
393The default value&nbsp;<span style="font-weight: bold;">building_wall_south</span>
394= <span style="font-style: italic;">( ( <a href="#ny">ny</a>&nbsp;+
3951 ) * <a href="#dy">dy</a> -&nbsp; <a href="#building_length_y">building_length_y</a> ) / 2</span>
396centers the building in y-direction. </td> </tr> <tr>
397<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="cloud_droplets"></a>cloud_droplets</span><br>
398</td> <td style="vertical-align: top;">L<br> </td>
399<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span><br> </td>
400<td style="vertical-align: top;">Parameter to switch on
401usage of cloud droplets.<br> <br>
402Cloud droplets require to use the particle package (<span style="font-weight: bold;">mrun</span>-option <span style="font-family: monospace;">-p particles</span>),
403so in this case a particle corresponds to a droplet. The droplet
404features (number of droplets, initial radius, etc.) can be steered with
405the&nbsp; respective particle parameters (see e.g. <a href="#chapter_4.2.html#radius">radius</a>).
406The real number of initial droplets in a grid cell is equal to the
407initial 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>
408<span lang="en-GB"><font face="Thorndale, serif">and
409</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>)
410times the <a href="#initial_weighting_factor">initial_weighting_factor</a>.<br>
412In case of using cloud droplets, the default condensation scheme in
413PALM cannot be used, i.e. <a href="#cloud_physics">cloud_physics</a>
414must be set <span style="font-style: italic;">.F.</span>.<br>
415</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="cloud_physics"></a><b>cloud_physics</b></p>
416</td> <td style="vertical-align: top;">L<br> </td>
417<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p>Parameter to switch
418on the condensation scheme.&nbsp; </p>
419For <b>cloud_physics =</b> <span style="font-style: italic;">.TRUE.</span>, equations
420for the
421liquid water&nbsp;
422content and the liquid water potential temperature are solved instead
423of those for specific humidity and potential temperature. Note
424that a grid volume is assumed to be either completely saturated or
426unsaturated (0%-or-100%-scheme). A simple precipitation scheme can
427additionally be switched on with parameter <a href="#precipitation">precipitation</a>.
428Also cloud-top cooling by longwave radiation can be utilized (see <a href="#radiation">radiation</a>)<br> <b><br>
429cloud_physics =</b> <span style="font-style: italic;">.TRUE.
430</span>requires <a href="#moisture">moisture</a>
431=<span style="font-style: italic;"> .TRUE.</span> .<br>
432Detailed information about the condensation scheme is given in the
433description of the <a href="">cloud
434physics module</a> (pdf-file, only in German).<br> <br>
435This condensation scheme is not allowed if cloud droplets are simulated
436explicitly (see <a href="#cloud_droplets">cloud_droplets</a>).<br>
437</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="conserve_volume_flow"></a>conserve_volume_flow</span></td>
438<td style="vertical-align: top;">L</td> <td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td>Conservation
439of volume flow in x- and y-direction.<br> <br> <span style="font-weight: bold;">conserve_volume_flow</span>
440= <span style="font-style: italic;">.TRUE.</span>
441guarantees that the volume flow through the xz- or yz-cross-section of
442the total model domain remains constant (equal to the initial value at
443t=0) throughout the run.<br>
444</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="cut_spline_overshoot"></a><b>cut_spline_overshoot</b></p>
445</td> <td style="vertical-align: top;">L</td>
446<td style="vertical-align: top;"><span style="font-style: italic;">.T.</span></td> <td style="vertical-align: top;"> <p>Cuts off of
447so-called overshoots, which can occur with the
448upstream-spline scheme.&nbsp; </p> <p><font color="#000000">The cubic splines tend to overshoot in
449case of discontinuous changes of variables between neighbouring grid
450points.</font><font color="#ff0000"> </font><font color="#000000">This
451may lead to errors in calculating the advection tendency.</font>
453of <b>cut_spline_overshoot</b> = <i>.TRUE.</i>
454(switched on by
456allows variable values not to exceed an interval defined by the
457respective adjacent grid points. This interval can be adjusted
458seperately for every prognostic variable (see initialization parameters
459<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>,
460etc.). This might be necessary in case that the
461default interval has a non-tolerable effect on the model
462results.&nbsp; </p> <p>Overshoots may also be removed
463using the parameters <a href="#ups_limit_e">ups_limit_e</a>,
464<a href="#ups_limit_pt">ups_limit_pt</a>,
465etc. as well as by applying a long-filter (see <a href="#long_filter_factor">long_filter_factor</a>).</p>
466</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="damp_level_1d"></a><b>damp_level_1d</b></p>
467</td> <td style="vertical-align: top;">R</td>
468<td style="vertical-align: top;"><span style="font-style: italic;">zu(nz+1)</span></td>
469<td style="vertical-align: top;"> <p>Height where
470the damping layer begins in the 1d-model
471(in m).&nbsp; </p> <p>This parameter is used to
472switch on a damping layer for the
4731d-model, which is generally needed for the damping of inertia
474oscillations. Damping is done by gradually increasing the value
475of the eddy diffusivities about 10% per vertical grid level
476(starting with the value at the height given by <b>damp_level_1d</b>,
477or possibly from the next grid pint above), i.e. K<sub>m</sub>(k+1)
4791.1 * K<sub>m</sub>(k).
480The values of K<sub>m</sub> are limited to 10 m**2/s at
481maximum.&nbsp; <br>
482This parameter only comes into effect if the 1d-model is switched on
484the initialization of the 3d-model using <a href="#initializing_actions">initializing_actions</a>
485= <span style="font-style: italic;">'set_1d-model_profiles'</span>.
486<br> </p> </td> </tr> <tr> <td style="vertical-align: top;"><a name="dissipation_1d"></a><span style="font-weight: bold;">dissipation_1d</span><br>
487</td> <td style="vertical-align: top;">C*20<br>
488</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>
489<td style="vertical-align: top;">Calculation method for
490the energy dissipation term in the TKE equation of the 1d-model.<br>
492By default the dissipation is calculated as in the 3d-model using diss
493= (0.19 + 0.74 * l / l_grid) * e**1.5 / l.<br> <br>
494Setting <span style="font-weight: bold;">dissipation_1d</span>
495= <span style="font-style: italic;">'detering'</span>
496forces the dissipation to be calculated as diss = 0.064 * e**1.5 / l.<br>
497</td> </tr>
498<tr> <td style="vertical-align: top;"> <p><a name="dt"></a><b>dt</b></p> </td>
499<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">variable</span></td>
500<td style="vertical-align: top;"> <p>Time step for
501the 3d-model (in s).&nbsp; </p> <p>By default, (i.e.
502if a Runge-Kutta scheme is used, see <a href="#timestep_scheme">timestep_scheme</a>)
503the value of the time step is calculating after each time step
504(following the time step criteria) and
505used for the next step.</p> <p>If the user assigns <b>dt</b>
506a value, then the time step is
507fixed to this value throughout the whole run (whether it fulfills the
508time step
509criteria or not). However, changes are allowed for restart runs,
510because <b>dt</b> can also be used as a <a href="chapter_4.2.html#dt_laufparameter">run
511parameter</a>.&nbsp; </p> <p>In case that the
512calculated time step meets the condition<br> </p> <ul>
513<p><b>dt</b> &lt; 0.00001 * <a href="chapter_4.2.html#dt_max">dt_max</a> (with dt_max
514= 20.0)</p> </ul> <p>the simulation will be
515aborted. Such situations usually arise
516in case of any numerical problem / instability which causes a
517non-realistic increase of the wind speed.&nbsp; </p> <p>A
518small time step due to a large mean horizontal windspeed
519speed may be enlarged by using a coordinate transformation (see <a href="#galilei_transformation">galilei_transformation</a>),
520in order to spare CPU time.<br> </p> <p>If the
521leapfrog timestep scheme is used (see <a href="#timestep_scheme">timestep_scheme</a>)
522a temporary time step value dt_new is calculated first, with dt_new = <a href="chapter_4.2.html#fcl_factor">cfl_factor</a>
523* dt_crit where dt_crit is the maximum timestep allowed by the CFL and
524diffusion condition. Next it is examined whether dt_new exceeds or
525falls below the
526value of the previous timestep by at
527least +5 % / -2%. If it is smaller, <span style="font-weight: bold;">dt</span>
528= dt_new is immediately used for the next timestep. If it is larger,
529then <span style="font-weight: bold;">dt </span>=
5301.02 * dt_prev
531(previous timestep) is used as the new timestep, however the time
532step is only increased if the last change of the time step is dated
533back at
534least 30 iterations. If dt_new is located in the interval mentioned
535above, then dt
536does not change at all. By doing so, permanent time step changes as
537well as large
538sudden changes (increases) in the time step are avoided.</p> </td>
539</tr> <tr> <td style="vertical-align: top;">
540<p><a name="dt_pr_1d"></a><b>dt_pr_1d</b></p>
541</td> <td style="vertical-align: top;">R</td>
542<td style="vertical-align: top;"><span style="font-style: italic;">9999999.9</span></td>
543<td style="vertical-align: top;"> <p>Temporal
544interval of vertical profile output of the 1D-model
545(in s).&nbsp; </p> <p>Data are written in ASCII
546format to file <a href="chapter_3.4.html#LIST_PROFIL_1D">LIST_PROFIL_1D</a>.
547This parameter is only in effect if the 1d-model has been switched on
548for the
549initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
550= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
551</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="dt_run_control_1d"></a><b>dt_run_control_1d</b></p>
552</td> <td style="vertical-align: top;">R</td>
553<td style="vertical-align: top;"><span style="font-style: italic;">60.0</span></td> <td style="vertical-align: top;"> <p>Temporal interval of
554runtime control output of the 1d-model
555(in s).&nbsp; </p> <p>Data are written in ASCII
556format to file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.
557This parameter is only in effect if the 1d-model is switched on for the
558initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
559= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
560</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="dx"></a><b>dx</b></p>
561</td> <td style="vertical-align: top;">R</td>
562<td style="vertical-align: top;"><span style="font-style: italic;">1.0</span></td> <td style="vertical-align: top;"> <p>Horizontal grid
563spacing along the x-direction (in m).&nbsp; </p> <p>Along
564x-direction only a constant grid spacing is allowed.</p> </td>
565</tr> <tr> <td style="vertical-align: top;">
566<p><a name="dy"></a><b>dy</b></p>
567</td> <td style="vertical-align: top;">R</td>
568<td style="vertical-align: top;"><span style="font-style: italic;">1.0</span></td> <td style="vertical-align: top;"> <p>Horizontal grid
569spacing along the x-direction (in m).&nbsp; </p> <p>Along
570x-direction only a constant grid spacing is allowed.</p> </td>
571</tr> <tr> <td style="vertical-align: top;">
572<p><a name="dz"></a><b>dz</b></p>
573</td> <td style="vertical-align: top;">R</td>
574<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Vertical grid
575spacing (in m).&nbsp; </p> <p>This parameter must be
576assigned by the user, because no
577default value is given.<br> </p> <p>By default, the
578model uses constant grid spacing along z-direction, but it can be
579stretched using the parameters <a href="#dz_stretch_level">dz_stretch_level</a>
580and <a href="#dz_stretch_factor">dz_stretch_factor</a>.
581In case of stretching, a maximum allowed grid spacing can be given by <a href="#dz_max">dz_max</a>.<br> </p> <p>Assuming
582a constant <span style="font-weight: bold;">dz</span>,
583the scalar levels (zu) are calculated directly by:&nbsp; </p>
584<ul> <p>zu(0) = - dz * 0.5&nbsp; <br>
585zu(1) = dz * 0.5</p> </ul> <p>The w-levels lie
586half between them:&nbsp; </p> <ul> <p>zw(k) =
587( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
588<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
589spacing (in m).<br><br>If the vertical grid is stretched
590(see <a href="#dz_stretch_factor">dz_stretch_factor</a>
591and <a href="#dz_stretch_level">dz_stretch_level</a>),
592<span style="font-weight: bold;">dz_max</span> can
593be used to limit the vertical grid spacing.</td></tr><tr>
594<td style="vertical-align: top;"> <p><a name="dz_stretch_factor"></a><b>dz_stretch_factor</b></p>
595</td> <td style="vertical-align: top;">R</td>
596<td style="vertical-align: top;"><span style="font-style: italic;">1.08</span></td> <td style="vertical-align: top;"> <p>Stretch factor for a
597vertically stretched grid (see <a href="#dz_stretch_level">dz_stretch_level</a>).&nbsp;
598</p> <p>The stretch factor should not exceed a value of
599approx. 1.10 -
6001.12, otherwise the discretization errors due to the stretched grid not
601negligible any more. (refer Kalnay de Rivas)</p> </td> </tr>
602<tr> <td style="vertical-align: top;"> <p><a name="dz_stretch_level"></a><b>dz_stretch_level</b></p>
603</td> <td style="vertical-align: top;">R</td>
604<td style="vertical-align: top;"><span style="font-style: italic;">100000.0</span><br> </td>
605<td style="vertical-align: top;"> <p>Height level
606above which the grid is to be stretched
607vertically (in m).&nbsp; </p> <p>The vertical grid
608spacings <a href="#dz">dz</a>
609above this level are calculated as&nbsp; </p> <ul> <p><b>dz</b>(k+1)
610= <b>dz</b>(k) * <a href="#dz_stretch_factor">dz_stretch_factor</a></p>
611</ul> <p>and used as spacings for the scalar levels (zu).
613w-levels are then defined as:&nbsp; </p> <ul> <p>zw(k)
614= ( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
615<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="e_min"></a>e_min</span></td>
616<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">0.0</span></td> <td>Minimum
617subgrid-scale TKE in m<sup>2</sup>s<sup>-2</sup>.<br>
619option&nbsp;adds artificial viscosity to the flow by ensuring that
621subgrid-scale TKE does not fall below the minimum threshold <span style="font-weight: bold;">e_min</span>.</td> </tr>
622<tr> <td style="vertical-align: top;"> <p><a name="end_time_1d"></a><b>end_time_1d</b></p>
623</td> <td style="vertical-align: top;">R</td>
624<td style="vertical-align: top;"><span style="font-style: italic;">864000.0</span><br> </td>
625<td style="vertical-align: top;"> <p>Time to be
626simulated for the 1d-model (in s).&nbsp; </p> <p>The
627default value corresponds to a simulated time of 10 days.
628Usually, after such a period the inertia oscillations have completely
629decayed and the solution of the 1d-model can be regarded as stationary
630(see <a href="#damp_level_1d">damp_level_1d</a>).
631This parameter is only in effect if the 1d-model is switched on for the
632initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
633= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
634</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="fft_method"></a><b>fft_method</b></p>
635</td> <td style="vertical-align: top;">C * 20</td>
636<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>
637<td style="vertical-align: top;"> <p>FFT-method to
638be used.<br> </p> <p><br>
639The fast fourier transformation (FFT) is used for solving the
640perturbation pressure equation with a direct method (see <a href="chapter_4.2.html#psolver">psolver</a>)
641and for calculating power spectra (see optional software packages,
642section <a href="chapter_4.2.html#spectra_package">4.2</a>).</p>
644By default, system-specific, optimized routines from external
645vendor libraries are used. However, these are available only on certain
646computers and there are more or less severe restrictions concerning the
647number of gridpoints to be used with them.<br> </p> <p>There
648are two other PALM internal methods available on every
649machine (their respective source code is part of the PALM source code):</p>
650<p>1.: The <span style="font-weight: bold;">Temperton</span>-method
651from Clive Temperton (ECWMF) which is computationally very fast and
652switched on with <b>fft_method</b> = <span style="font-style: italic;">'temperton-algorithm'</span>.
653The number of horizontal gridpoints (nx+1, ny+1) to be used with this
654method must be composed of prime factors 2, 3 and 5.<br> </p>
6552.: The <span style="font-weight: bold;">Singleton</span>-method
656which is very slow but has no restrictions concerning the number of
657gridpoints to be used with, switched on with <b>fft_method</b>
658= <span style="font-style: italic;">'singleton-algorithm'</span>.
659</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="galilei_transformation"></a><b>galilei_transformation</b></p>
660</td> <td style="vertical-align: top;">L</td>
661<td style="vertical-align: top;"><i>.F.</i></td>
662<td style="vertical-align: top;">Application of a
663Galilei-transformation to the
665system of the model.<br><p>With <b>galilei_transformation</b>
666= <i>.T.,</i> a so-called
667Galilei-transformation is switched on which ensures that the coordinate
668system of the model is moved along with the geostrophical wind.
669Alternatively, the model domain can be moved along with the averaged
670horizontal wind (see <a href="#use_ug_for_galilei_tr">use_ug_for_galilei_tr</a>,
671this can and will naturally change in time). With this method,
672numerical inaccuracies of the Piascek - Williams - scheme (concerns in
673particular the momentum advection) are minimized. Beyond that, in the
674majority of cases the lower relative velocities in the moved system
675permit a larger time step (<a href="#dt">dt</a>).
676Switching the transformation on is only worthwhile if the geostrophical
677wind (ug, vg)
678and the averaged horizontal wind clearly deviate from the value 0. In
679each case, the distance the coordinate system has been moved is written
680to the file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.&nbsp;
681</p> <p>Non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
682and <a href="#bc_ns">bc_ns</a>), the specification
683of a gestrophic
684wind that is not constant with height
685as well as e.g. stationary inhomogeneities at the bottom boundary do
686not allow the use of this transformation.</p> </td> </tr>
687<tr> <td style="vertical-align: top;"> <p><a name="grid_matching"></a><b>grid_matching</b></p>
688</td> <td style="vertical-align: top;">C * 6</td>
689<td style="vertical-align: top;"><span style="font-style: italic;">'match'</span></td> <td style="vertical-align: top;">Variable to adjust the
691sizes in parallel runs.<br> <br>
692For <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>,
693the subdomains are forced to have an identical
694size on all processors. In this case the processor numbers in the
695respective directions of the virtual processor net must fulfill certain
696divisor conditions concerning the grid point numbers in the three
697directions (see <a href="#nx">nx</a>, <a href="#ny">ny</a>
698and <a href="#nz">nz</a>).
699Advantage of this method is that all PEs bear the same computational
700load.<br> <br>
701There is no such restriction by default, because then smaller
702subdomains are allowed on those processors which
703form the right and/or north boundary of the virtual processor grid. On
704all other processors the subdomains are of same size. Whether smaller
705subdomains are actually used, depends on the number of processors and
706the grid point numbers used. Information about the respective settings
707are 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>
709When using a multi-grid method for solving the Poisson equation (see <a href="">psolver</a>)
710only <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>
711is allowed.<br> <br> <b>Note:</b><br>
712In some cases for small processor numbers there may be a very bad load
713balancing among the
714processors which may reduce the performance of the code.</td> </tr>
715<tr> <td style="vertical-align: top;"><a name="inflow_disturbance_begin"></a><b>inflow_disturbance_<br>
716begin</b></td> <td style="vertical-align: top;">I</td>
717<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>
718<td style="vertical-align: top;">Lower
719limit of the horizontal range for which random perturbations are to be
720imposed on the horizontal velocity field (gridpoints).<br> <br>
721If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
722or <a href="#bc_ns">bc_ns</a>),
723this parameter gives the gridpoint number (counted horizontally from
724the inflow)&nbsp; from which on perturbations are imposed on the
725horizontal velocity field. Perturbations must be switched on with
726parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
727</tr> <tr> <td style="vertical-align: top;"><a name="inflow_disturbance_end"></a><b>inflow_disturbance_<br>
728end</b></td> <td style="vertical-align: top;">I</td>
729<td style="vertical-align: top;"><span style="font-style: italic;">MIN(100,</span><br style="font-style: italic;"> <span style="font-style: italic;">3/4*nx or</span><br style="font-style: italic;"> <span style="font-style: italic;">3/4*ny)</span></td> <td style="vertical-align: top;">Upper
730limit of the horizontal range for which random perturbations are
731to be imposed on the horizontal velocity field (gridpoints).<br> <br>
732If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
733or <a href="#bc_ns">bc_ns</a>),
734this parameter gives the gridpoint number (counted horizontally from
735the inflow)&nbsp; unto which perturbations are imposed on the
737velocity field. Perturbations must be switched on with parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
738</tr> <tr> <td style="vertical-align: top;">
739<p><a name="initializing_actions"></a><b>initializing_actions</b></p>
740</td> <td style="vertical-align: top;">C * 100</td>
741<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p style="font-style: normal;">Initialization actions
742to be carried out.&nbsp; </p> <p style="font-style: normal;">This parameter does not have a
743default value and therefore must be assigned with each model run. For
744restart runs <b>initializing_actions</b> = <span style="font-style: italic;">'read_restart_data'</span>
745must be set. For the initial run of a job chain the following values
746are allowed:&nbsp; </p> <p style="font-style: normal;"><span style="font-style: italic;">'set_constant_profiles'</span>
747</p> <ul> <p>A horizontal wind profile consisting
748of linear sections (see <a href="#ug_surface">ug_surface</a>,
749<a href="#ug_vertical_gradient">ug_vertical_gradient</a>,
750<a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
751and <a href="#vg_surface">vg_surface</a>, <a href="#vg_vertical_gradient">vg_vertical_gradient</a>,
752<a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
753respectively) as well as a vertical temperature (humidity) profile
754consisting of
755linear sections (see <a href="#pt_surface">pt_surface</a>,
756<a href="#pt_vertical_gradient">pt_vertical_gradient</a>,
757<a href="#q_surface">q_surface</a>
758and <a href="#q_vertical_gradient">q_vertical_gradient</a>)
759are assumed as initial profiles. The subgrid-scale TKE is set to 0 but K<sub>m</sub>
760and K<sub>h</sub> are set to very small values because
761otherwise no TKE
762would be generated.</p> </ul> <p style="font-style: italic;">'set_1d-model_profiles' </p>
763<ul> <p>The arrays of the 3d-model are initialized with
765(stationary) solution of the 1d-model. These are the variables e, kh,
766km, u, v and with Prandtl layer switched on rif, us, usws, vsws. The
767temperature (humidity) profile consisting of linear sections is set as
768for 'set_constant_profiles' and assumed as constant in time within the
7691d-model. For steering of the 1d-model a set of parameters with suffix
770"_1d" (e.g. <a href="#end_time_1d">end_time_1d</a>,
771<a href="#damp_level_1d">damp_level_1d</a>)
772is available.</p> </ul> <p><span style="font-style: italic;">'by_user'</span></p><p style="margin-left: 40px;">The initialization of the arrays
773of the 3d-model is under complete control of the user and has to be
774done in routine <a href="chapter_3.5.1.html#user_init_3d_model">user_init_3d_model</a>
775of the user-interface.<span style="font-style: italic;"></span></p><p><span style="font-style: italic;">'initialize_vortex'</span>
776</p> <div style="margin-left: 40px;">The initial
777velocity field of the
7783d-model corresponds to a
779Rankine-vortex with vertical axis. This setting may be used to test
780advection 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>)
781are necessary. In order not to distort the vortex, an initial
782horizontal wind profile constant
783with height is necessary (to be set by <b>initializing_actions</b>
784= <span style="font-style: italic;">'set_constant_profiles'</span>)
785and some other conditions have to be met (neutral stratification,
786diffusion must be
787switched off, see <a href="#km_constant">km_constant</a>).
788The center of the vortex is located at jc = (nx+1)/2. It
789extends from k = 0 to k = nz+1. Its radius is 8 * <a href="#dx">dx</a>
790and the exponentially decaying part ranges to 32 * <a href="#dx">dx</a>
791(see init_rankine.f90). </div> <p><span style="font-style: italic;">'initialize_ptanom'</span>
792</p> <ul> <p>A 2d-Gauss-like shape disturbance
793(x,y) is added to the
794initial temperature field with radius 10.0 * <a href="#dx">dx</a>
795and center at jc = (nx+1)/2. This may be used for tests of scalar
796advection schemes
797(see <a href="#scalar_advec">scalar_advec</a>).
798Such tests require a horizontal wind profile constant with hight and
800switched off (see <span style="font-style: italic;">'initialize_vortex'</span>).
801Additionally, the buoyancy term
802must be switched of in the equation of motion&nbsp; for w (this
803requires the user to comment out the call of <span style="font-family: monospace;">buoyancy</span> in the
804source code of <span style="font-family: monospace;">prognostic_equations.f90</span>).</p>
805</ul> <p style="font-style: normal;">Values may be
806combined, e.g. <b>initializing_actions</b> = <span style="font-style: italic;">'set_constant_profiles
807initialize_vortex'</span>, but the values of <span style="font-style: italic;">'set_constant_profiles'</span>,
808<span style="font-style: italic;">'set_1d-model_profiles'</span>
809, and <span style="font-style: italic;">'by_user'</span>
810must not be given at the same time.</p> <p style="font-style: italic;"> </p> </td> </tr>
811<tr> <td style="vertical-align: top;"> <p><a name="km_constant"></a><b>km_constant</b></p>
812</td> <td style="vertical-align: top;">R</td>
813<td style="vertical-align: top;"><i>variable<br>
814(computed from TKE)</i></td> <td style="vertical-align: top;"> <p>Constant eddy
815diffusivities are used (laminar
816simulations).&nbsp; </p> <p>If this parameter is
817specified, both in the 1d and in the
8183d-model constant values for the eddy diffusivities are used in
819space and time with K<sub>m</sub> = <b>km_constant</b>
820and K<sub>h</sub> = K<sub>m</sub> / <a href="chapter_4.2.html#prandtl_number">prandtl_number</a>.
821The prognostic equation for the subgrid-scale TKE is switched off.
822Constant eddy diffusivities are only allowed with the Prandtl layer (<a href="#prandtl_layer">prandtl_layer</a>)
823switched off.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="km_damp_max"></a><b>km_damp_max</b></p>
824</td> <td style="vertical-align: top;">R</td>
825<td style="vertical-align: top;"><span style="font-style: italic;">0.5*(dx
826or dy)</span></td> <td style="vertical-align: top;">Maximum
827diffusivity used for filtering the velocity field in the vicinity of
828the outflow (in m<sup>2</sup>/s).<br> <br>
829When using non-cyclic lateral boundaries (see <a href="#bc_lr">bc_lr</a>
830or <a href="#bc_ns">bc_ns</a>),
831a smoothing has to be applied to the
832velocity field in the vicinity of the outflow in order to suppress any
833reflections of outgoing disturbances. Smoothing is done by increasing
834the eddy diffusivity along the horizontal direction which is
835perpendicular to the outflow boundary. Only velocity components
836parallel to the outflow boundary are filtered (e.g. v and w, if the
837outflow is along x). Damping is applied from the bottom to the top of
838the domain.<br> <br>
839The horizontal range of the smoothing is controlled by <a href="#outflow_damping_width">outflow_damping_width</a>
840which defines the number of gridpoints (counted from the outflow
841boundary) from where on the smoothing is applied. Starting from that
842point, the eddy diffusivity is linearly increased (from zero to its
843maximum value given by <span style="font-weight: bold;">km_damp_max</span>)
844until half of the damping range width, from where it remains constant
845up to the outflow boundary. If at a certain grid point the eddy
846diffusivity calculated from the flow field is larger than as described
847above, it is used instead.<br> <br>
848The default value of <span style="font-weight: bold;">km_damp_max</span>
849has been empirically proven to be sufficient.</td> </tr> <tr>
850<td style="vertical-align: top;"> <p><a name="long_filter_factor"></a><b>long_filter_factor</b></p>
851</td> <td style="vertical-align: top;">R</td>
852<td style="vertical-align: top;"><i>0.0</i></td>
853<td style="vertical-align: top;"> <p>Filter factor
854for the so-called Long-filter.<br> </p> <p><br>
855This filter very efficiently
856eliminates 2-delta-waves sometimes cauesed by the upstream-spline
857scheme (see Mahrer and
858Pielke, 1978: Mon. Wea. Rev., 106, 818-830). It works in all three
859directions in space. A value of <b>long_filter_factor</b>
860= <i>0.01</i>
861sufficiently removes the small-scale waves without affecting the
862longer waves.<br> </p> <p>By default, the filter is
863switched off (= <i>0.0</i>).
864It is exclusively applied to the tendencies calculated by the
865upstream-spline scheme (see <a href="#momentum_advec">momentum_advec</a>
866and <a href="#scalar_advec">scalar_advec</a>),
867not to the prognostic variables themselves. At the bottom and top
868boundary of the model domain the filter effect for vertical
8692-delta-waves is reduced. There, the amplitude of these waves is only
870reduced by approx. 50%, otherwise by nearly 100%.&nbsp; <br>
871Filter factors with values &gt; <i>0.01</i> also
872reduce the amplitudes
873of waves with wavelengths longer than 2-delta (see the paper by Mahrer
875Pielke, 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
876default, the optimization method depends on the host on which PALM is
877running. On machines with vector-type CPUs, single 3d-loops are used to
878calculate each tendency term of each prognostic equation, while on all
879other machines, all prognostic equations are solved within one big loop
880over 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>
881<td style="vertical-align: top;"><a name="mixing_length_1d"></a><span style="font-weight: bold;">mixing_length_1d</span><br>
882</td> <td style="vertical-align: top;">C*20<br>
883</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>
884<td style="vertical-align: top;">Mixing length used in the
8851d-model.<br> <br>
886By default the mixing length is calculated as in the 3d-model (i.e. it
887depends on the grid spacing).<br> <br>
888By setting <span style="font-weight: bold;">mixing_length_1d</span>
889= <span style="font-style: italic;">'blackadar'</span>,
890the so-called Blackadar mixing length is used (l = kappa * z / ( 1 +
891kappa * z / lambda ) with the limiting value lambda = 2.7E-4 * u_g / f).<br>
892</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="moisture"></a><b>moisture</b></p>
893</td> <td style="vertical-align: top;">L</td>
894<td style="vertical-align: top;"><i>.F.</i></td>
895<td style="vertical-align: top;"> <p>Parameter to
896switch on the prognostic equation for specific
897humidity q.<br> </p> <p>The initial vertical
898profile 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>
899and <a href="chapter_4.1.html#q_vertical_gradient_level">q_vertical_gradient_level</a>.&nbsp;
900Boundary conditions can be set via <a href="chapter_4.1.html#q_surface_initial_change">q_surface_initial_change</a>
901and <a href="chapter_4.1.html#surface_waterflux">surface_waterflux</a>.<br>
903If the condensation scheme is switched on (<a href="chapter_4.1.html#cloud_physics">cloud_physics</a>
904= .TRUE.), q becomes the total liquid water content (sum of specific
905humidity and liquid water content).</td> </tr>
906<tr> <td style="vertical-align: top;"> <p><a name="momentum_advec"></a><b>momentum_advec</b></p>
907</td> <td style="vertical-align: top;">C * 10</td>
908<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
909<td style="vertical-align: top;"> <p>Advection
910scheme to be used for the momentum equations.<br> <br>
911The user can choose between the following schemes:<br>
912&nbsp;<br> <br> <span style="font-style: italic;">'pw-scheme'</span><br>
913</p> <div style="margin-left: 40px;">The scheme of
914Piascek and
915Williams (1970, J. Comp. Phys., 6,
916392-405) with central differences in the form C3 is used.<br>
917If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
918= <span style="font-style: italic;">'leapfrog+euler'</span>
920advection scheme is - for the Euler-timestep - automatically switched
921to an upstream-scheme.<br> </div> <p> </p> <p><span style="font-style: italic;">'ups-scheme'</span><br>
922</p> <div style="margin-left: 40px;">The
923upstream-spline scheme is
925(see Mahrer and Pielke,
9261978: Mon. Wea. Rev., 106, 818-830). In opposite to the
927Piascek-Williams scheme, this is characterized by much better numerical
928features (less numerical diffusion, better preservation of flow
929structures, e.g. vortices), but computationally it is much more
930expensive. In
931addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
932= <span style="font-style: italic;">'</span><i>euler'</i>),
933i.e. the
934timestep accuracy is only of first order.
935For this reason the advection of scalar variables (see <a href="#scalar_advec">scalar_advec</a>)
936should then also be carried out with the upstream-spline scheme,
937because otherwise the scalar variables would
938be subject to large numerical diffusion due to the upstream
939scheme.&nbsp; </div> <p style="margin-left: 40px;">Since
940the cubic splines used tend
941to overshoot under
942certain circumstances, this effect must be adjusted by suitable
943filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
944<a href="#long_filter_factor">long_filter_factor</a>,
945<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>).
946This is always neccessary for runs with stable stratification,
947even if this stratification appears only in parts of the model domain.<br>
948</p> <div style="margin-left: 40px;">With stable
949stratification the
950upstream-spline scheme also
951produces gravity waves with large amplitude, which must be
952suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
953<br> <span style="font-weight: bold;">Important: </span>The&nbsp;
954upstream-spline scheme is not implemented for humidity and passive
955scalars (see <a href="#moisture">moisture</a>
956and <a href="#passive_scalar">passive_scalar</a>)
957and requires the use of a 2d-domain-decomposition. The last conditions
958severely restricts code optimization on several machines leading to
959very long execution times! The scheme is also not allowed for
960non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
961and <a href="#bc_ns">bc_ns</a>).</div> </td>
962</tr> <tr> <td style="vertical-align: top;"><a name="netcdf_precision"></a><span style="font-weight: bold;">netcdf_precision</span><br>
963</td> <td style="vertical-align: top;">C*20<br>
964(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>
965<td style="vertical-align: top;">Defines the accuracy of
966the NetCDF output.<br> <br>
967By default, all NetCDF output data (see <a href="chapter_4.2.html#data_output_format">data_output_format</a>)
968have single precision&nbsp; (4 byte) accuracy. Double precision (8
969byte) can be choosen alternatively.<br>
970Accuracy for the different output data (cross sections, 3d-volume data,
971spectra, etc.) can be set independently.<br> <span style="font-style: italic;">'&lt;out&gt;_NF90_REAL4'</span>
972(single precision) or <span style="font-style: italic;">'&lt;out&gt;_NF90_REAL8'</span>
973(double precision) are the two principally allowed values for <span style="font-weight: bold;">netcdf_precision</span>,
974where the string <span style="font-style: italic;">'&lt;out&gt;'
975</span>can be chosen out of the following list:<br> <br>
976<table style="text-align: left; width: 284px; height: 234px;" border="1" cellpadding="2" cellspacing="2"> <tbody>
977<tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xy'</span><br> </td>
978<td style="vertical-align: top;">horizontal cross section<br>
979</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xz'</span><br> </td>
980<td style="vertical-align: top;">vertical (xz) cross
981section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'yz'</span><br> </td>
982<td style="vertical-align: top;">vertical (yz) cross
983section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'2d'</span><br> </td>
984<td style="vertical-align: top;">all cross sections<br>
985</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'3d'</span><br> </td>
986<td style="vertical-align: top;">volume data<br> </td>
987</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'pr'</span><br> </td>
988<td style="vertical-align: top;">vertical profiles<br>
989</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'ts'</span><br> </td>
990<td style="vertical-align: top;">time series, particle
991time series<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'sp'</span><br> </td>
992<td style="vertical-align: top;">spectra<br> </td>
993</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'prt'</span><br> </td>
994<td style="vertical-align: top;">particles<br> </td>
995</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'all'</span><br> </td>
996<td style="vertical-align: top;">all output quantities<br>
997</td> </tr> </tbody> </table> <br> <span style="font-weight: bold;">Example:</span><br>
998If all cross section data and the particle data shall be output in
999double 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>
1000has to be assigned.<br> </td> </tr>
1001<tr> <td style="vertical-align: top;"> <p><a name="npex"></a><b>npex</b></p> </td>
1002<td style="vertical-align: top;">I</td> <td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
1003along x-direction of the virtual
1005net.&nbsp; </p> <p>For parallel runs, the total
1006number of processors to be used
1007is given by
1008the <span style="font-weight: bold;">mrun</span>
1009option <a href="">-X</a>.
1010By default, depending on the type of the parallel computer, PALM
1011generates a 1d processor
1012net (domain decomposition along x, <span style="font-weight: bold;">npey</span>
1013= <span style="font-style: italic;">1</span>) or a
10142d-net (this is
1015favored on machines with fast communication network). In case of a
10162d-net, it is tried to make it more or less square-shaped. If, for
1017example, 16 processors are assigned (-X 16), a 4 * 4 processor net is
1018generated (<span style="font-weight: bold;">npex</span>
1019= <span style="font-style: italic;">4</span>, <span style="font-weight: bold;">npey</span>
1020= <span style="font-style: italic;">4</span>).
1021This choice is optimal for square total domains (<a href="#nx">nx</a>
1022= <a href="#ny">ny</a>),
1023since then the number of ghost points at the lateral boundarys of
1024the subdomains is minimal. If <span style="font-weight: bold;">nx</span>
1025nd <span style="font-weight: bold;">ny</span>
1026differ extremely, the
1027processor net should be manually adjusted using adequate values for <span style="font-weight: bold;">npex</span> and <span style="font-weight: bold;">npey</span>.&nbsp; </p>
1028<p><b>Important:</b> The value of <span style="font-weight: bold;">npex</span> * <span style="font-weight: bold;">npey</span> must exactly
1029correspond to the
1030value assigned by the <span style="font-weight: bold;">mrun</span>-option
1032Otherwise the model run will abort with a corresponding error
1033message.&nbsp; <br>
1034Additionally, the specification of <span style="font-weight: bold;">npex</span>
1035and <span style="font-weight: bold;">npey</span>
1036may of course
1037override the default setting for the domain decomposition (1d or 2d)
1038which may have a significant (negative) effect on the code performance.
1039</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="npey"></a><b>npey</b></p>
1040</td> <td style="vertical-align: top;">I</td>
1041<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
1042along y-direction of the virtual
1044net.&nbsp; </p> <p>For further information see <a href="#npex">npex</a>.</p> </td> </tr>
1045<tr> <td style="vertical-align: top;"> <p><a name="nsor_ini"></a><b>nsor_ini</b></p>
1046</td> <td style="vertical-align: top;">I</td>
1047<td style="vertical-align: top;"><i>100</i></td>
1048<td style="vertical-align: top;"> <p>Initial number
1049of iterations with the SOR algorithm.&nbsp; </p> <p>This
1050parameter is only effective if the SOR algorithm was
1051selected as the pressure solver scheme (<a href="chapter_4.2.html#psolver">psolver</a>
1052= <span style="font-style: italic;">'sor'</span>)
1053and specifies the
1054number of initial iterations of the SOR
1055scheme (at t = 0). The number of subsequent iterations at the following
1056timesteps is determined
1057with the parameter <a href="#nsor">nsor</a>.
1058Usually <b>nsor</b> &lt; <b>nsor_ini</b>,
1059since in each case
1060subsequent calls to <a href="chapter_4.2.html#psolver">psolver</a>
1061use the solution of the previous call as initial value. Suitable
1062test runs should determine whether sufficient convergence of the
1063solution is obtained with the default value and if necessary the value
1064of <b>nsor_ini</b> should be changed.</p> </td>
1065</tr> <tr> <td style="vertical-align: top;">
1066<p><a name="nx"></a><b>nx</b></p>
1067</td> <td style="vertical-align: top;">I</td>
1068<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1069points in x-direction.&nbsp; </p> <p>A value for this
1070parameter must be assigned. Since the lower
1071array bound in PALM
1072starts with i = 0, the actual number of grid points is equal to <b>nx+1</b>.
1073In case of cyclic boundary conditions along x, the domain size is (<b>nx+1</b>)*
1074<a href="#dx">dx</a>.</p> <p>For
1075parallel runs, in case of <a href="#grid_matching">grid_matching</a>
1076= <span style="font-style: italic;">'strict'</span>,
1077<b>nx+1</b> must
1078be an integral multiple
1079of the processor numbers (see <a href="#npex">npex</a>
1080and <a href="#npey">npey</a>)
1081along x- as well as along y-direction (due to data
1082transposition restrictions).</p> </td> </tr> <tr>
1083<td style="vertical-align: top;"> <p><a name="ny"></a><b>ny</b></p>
1084</td> <td style="vertical-align: top;">I</td>
1085<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1086points in y-direction.&nbsp; </p> <p>A value for this
1087parameter must be assigned. Since the lower
1088array bound in PALM starts with i = 0, the actual number of grid points
1089is equal to <b>ny+1</b>. In case of cyclic boundary
1090conditions along
1091y, the domain size is (<b>ny+1</b>) * <a href="#dy">dy</a>.</p>
1092<p>For parallel runs, in case of <a href="#grid_matching">grid_matching</a>
1093= <span style="font-style: italic;">'strict'</span>,
1094<b>ny+1</b> must
1095be an integral multiple
1096of the processor numbers (see <a href="#npex">npex</a>
1097and <a href="#npey">npey</a>)&nbsp;
1098along y- as well as along x-direction (due to data
1099transposition restrictions).</p> </td> </tr> <tr>
1100<td style="vertical-align: top;"> <p><a name="nz"></a><b>nz</b></p>
1101</td> <td style="vertical-align: top;">I</td>
1102<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1103points in z-direction.&nbsp; </p> <p>A value for this
1104parameter must be assigned. Since the lower
1105array bound in PALM
1106starts with k = 0 and since one additional grid point is added at the
1107top boundary (k = <b>nz+1</b>), the actual number of grid
1108points is <b>nz+2</b>.
1109However, the prognostic equations are only solved up to <b>nz</b>
1112or up to <b>nz-1</b> (w, scalar quantities). The top
1113boundary for u
1114and v is at k = <b>nz+1</b> (u, v) while at k = <b>nz</b>
1115for all
1116other quantities.&nbsp; </p> <p>For parallel
1117runs,&nbsp; in case of <a href="#grid_matching">grid_matching</a>
1118= <span style="font-style: italic;">'strict'</span>,
1119<b>nz</b> must
1120be an integral multiple of
1121the number of processors in x-direction (due to data transposition
1122restrictions).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="omega"></a><b>omega</b></p>
1123</td> <td style="vertical-align: top;">R</td>
1124<td style="vertical-align: top;"><i>7.29212E-5</i></td>
1125<td style="vertical-align: top;"> <p>Angular
1126velocity of the rotating system (in rad s<sup>-1</sup>).&nbsp;
1127</p> <p>The angular velocity of the earth is set by
1128default. The
1130of the Coriolis parameters are calculated as:&nbsp; </p> <ul>
1131<p>f = 2.0 * <b>omega</b> * sin(<a href="#phi">phi</a>)&nbsp;
1132<br>f* = 2.0 * <b>omega</b> * cos(<a href="#phi">phi</a>)</p>
1133</ul> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="outflow_damping_width"></a><b>outflow_damping_width</b></p>
1134</td> <td style="vertical-align: top;">I</td>
1135<td style="vertical-align: top;"><span style="font-style: italic;">MIN(20,
1136nx/2</span> or <span style="font-style: italic;">ny/2)</span></td>
1137<td style="vertical-align: top;">Width of
1138the damping range in the vicinity of the outflow (gridpoints).<br>
1140When using non-cyclic lateral boundaries (see <a href="chapter_4.1.html#bc_lr">bc_lr</a>
1141or <a href="chapter_4.1.html#bc_ns">bc_ns</a>),
1142a smoothing has to be applied to the
1143velocity field in the vicinity of the outflow in order to suppress any
1144reflections of outgoing disturbances. This parameter controlls the
1145horizontal range to which the smoothing is applied. The range is given
1146in gridpoints counted from the respective outflow boundary. For further
1147details about the smoothing see parameter <a href="chapter_4.1.html#km_damp_max">km_damp_max</a>,
1148which defines the magnitude of the damping.</td> </tr>
1149<tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_e"></a><b>overshoot_limit_e</b></p>
1150</td> <td style="vertical-align: top;">R</td>
1151<td style="vertical-align: top;"><i>0.0</i></td>
1152<td style="vertical-align: top;"> <p>Allowed limit
1153for the overshooting of subgrid-scale TKE in
1154case that the upstream-spline scheme is switched on (in m<sup>2</sup>/s<sup>2</sup>).&nbsp;
1155</p> <p>By deafult, if cut-off of overshoots is switched
1156on for the
1157upstream-spline scheme (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>),
1158no overshoots are permitted at all. If <b>overshoot_limit_e</b>
1159is given a non-zero value, overshoots with the respective
1160amplitude (both upward and downward) are allowed.&nbsp; </p>
1161<p>Only positive values are allowed for <b>overshoot_limit_e</b>.</p>
1162</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_pt"></a><b>overshoot_limit_pt</b></p>
1163</td> <td style="vertical-align: top;">R</td>
1164<td style="vertical-align: top;"><i>0.0</i></td>
1165<td style="vertical-align: top;"> <p>Allowed limit
1166for the overshooting of potential temperature in
1167case that the upstream-spline scheme is switched on (in K).&nbsp; </p>
1168<p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1169</p> <p>Only positive values are allowed for <b>overshoot_limit_pt</b>.</p>
1170</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_u"></a><b>overshoot_limit_u</b></p>
1171</td> <td style="vertical-align: top;">R</td>
1172<td style="vertical-align: top;"><i>0.0</i></td>
1173<td style="vertical-align: top;">Allowed limit for the
1174overshooting of
1175the u-component of velocity in case that the upstream-spline scheme is
1176switched on (in m/s). <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1177</p> <p>Only positive values are allowed for <b>overshoot_limit_u</b>.</p>
1178</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_v"></a><b>overshoot_limit_v</b></p>
1179</td> <td style="vertical-align: top;">R</td>
1180<td style="vertical-align: top;"><i>0.0</i></td>
1181<td style="vertical-align: top;"> <p>Allowed limit
1182for the overshooting of the v-component of
1183velocity in case that the upstream-spline scheme is switched on
1184(in m/s).&nbsp; </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1185</p> <p>Only positive values are allowed for <b>overshoot_limit_v</b>.</p>
1186</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_w"></a><b>overshoot_limit_w</b></p>
1187</td> <td style="vertical-align: top;">R</td>
1188<td style="vertical-align: top;"><i>0.0</i></td>
1189<td style="vertical-align: top;"> <p>Allowed limit
1190for the overshooting of the w-component of
1191velocity in case that the upstream-spline scheme is switched on
1192(in m/s).&nbsp; </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1193</p> <p>Only positive values are permitted for <b>overshoot_limit_w</b>.</p>
1194</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="passive_scalar"></a><b>passive_scalar</b></p>
1195</td> <td style="vertical-align: top;">L</td>
1196<td style="vertical-align: top;"><i>.F.</i></td>
1197<td style="vertical-align: top;"> <p>Parameter to
1198switch on the prognostic equation for a passive
1199scalar. <br> </p> <p>The initial vertical profile
1200of s can be set via parameters <a href="#s_surface">s_surface</a>,
1201<a href="#s_vertical_gradient">s_vertical_gradient</a>
1202and&nbsp; <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
1203Boundary conditions can be set via <a href="#s_surface_initial_change">s_surface_initial_change</a>
1204and <a href="#surface_scalarflux">surface_scalarflux</a>.&nbsp;
1205</p> <p><b>Note:</b> <br>
1206With <span style="font-weight: bold;">passive_scalar</span>
1208on, the simultaneous use of humidity (see <a href="#moisture">moisture</a>)
1209is impossible.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="phi"></a><b>phi</b></p>
1210</td> <td style="vertical-align: top;">R</td>
1211<td style="vertical-align: top;"><i>55.0</i></td>
1212<td style="vertical-align: top;"> <p>Geographical
1213latitude (in degrees).&nbsp; </p> <p>The value of
1214this parameter determines the value of the
1215Coriolis parameters f and f*, provided that the angular velocity (see <a href="#omega">omega</a>)
1216is non-zero.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="prandtl_layer"></a><b>prandtl_layer</b></p>
1217</td> <td style="vertical-align: top;">L</td>
1218<td style="vertical-align: top;"><i>.T.</i></td>
1219<td style="vertical-align: top;"> <p>Parameter to
1220switch on a Prandtl layer.&nbsp; </p> <p>By default,
1221a Prandtl layer is switched on at the bottom
1222boundary between z = 0 and z = 0.5 * <a href="#dz">dz</a>
1223(the first computational grid point above ground for u, v and the
1224scalar quantities).
1225In this case, at the bottom boundary, free-slip conditions for u and v
1226(see <a href="#bc_uv_b">bc_uv_b</a>)
1227are not allowed. Likewise, laminar
1228simulations with constant eddy diffusivities (<a href="#km_constant">km_constant</a>)
1229are forbidden.&nbsp; </p> <p>With Prandtl-layer
1230switched off, the TKE boundary condition <a href="#bc_e_b">bc_e_b</a>
1231= '<i>(u*)**2+neumann'</i> must not be used and is
1233changed to <i>'neumann'</i> if necessary.&nbsp; Also,
1234the pressure
1235boundary condition <a href="#bc_p_b">bc_p_b</a>
1236= <i>'neumann+inhomo'</i>&nbsp; is not allowed. </p>
1237<p>The roughness length is declared via the parameter <a href="#roughness_length">roughness_length</a>.</p>
1238</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="precipitation"></a><b>precipitation</b></p>
1239</td> <td style="vertical-align: top;">L</td>
1240<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p>Parameter to switch
1241on the precipitation scheme.<br> </p> <p>For
1242precipitation processes PALM uses a simplified Kessler
1243scheme. This scheme only considers the
1244so-called autoconversion, that means the generation of rain water by
1245coagulation of cloud drops among themselves. Precipitation begins and
1246is immediately removed from the flow as soon as the liquid water
1247content 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>
1248<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
1249refrence</span></td><td style="vertical-align: top;">Reference
1250temperature to be used in all buoyancy terms (in K).<br><br>By
1251default, the instantaneous horizontal average over the total model
1252domain is used.</td></tr><tr> <td style="vertical-align: top;"> <p><a name="pt_surface"></a><b>pt_surface</b></p>
1253</td> <td style="vertical-align: top;">R</td>
1254<td style="vertical-align: top;"><i>300.0</i></td>
1255<td style="vertical-align: top;"> <p>Surface
1256potential temperature (in K).&nbsp; </p> <p>This
1257parameter assigns the value of the potential temperature
1258pt at the surface (k=0)<b>.</b> Starting from this value,
1260initial vertical temperature profile is constructed with <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1261and <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level
1263This profile is also used for the 1d-model as a stationary profile.</p>
1264</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_surface_initial_change"></a><b>pt_surface_initial</b>
1265<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>
1266<td style="vertical-align: top;"> <p>Change in
1267surface temperature to be made at the beginning of
1268the 3d run
1269(in K).&nbsp; </p> <p>If <b>pt_surface_initial_change</b>
1270is set to a non-zero
1271value, the near surface sensible heat flux is not allowed to be given
1272simultaneously (see <a href="#surface_heatflux">surface_heatflux</a>).</p>
1273</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient"></a><b>pt_vertical_gradient</b></p>
1274</td> <td style="vertical-align: top;">R (10)</td>
1275<td style="vertical-align: top;"><i>10 * 0.0</i></td>
1276<td style="vertical-align: top;"> <p>Temperature
1277gradient(s) of the initial temperature profile (in
1279/ 100 m).&nbsp; </p> <p>This temperature gradient
1280holds starting from the height&nbsp;
1281level defined by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>
1282(precisely: for all uv levels k where zu(k) &gt;
1284pt_init(k) is set: pt_init(k) = pt_init(k-1) + dzu(k) * <b>pt_vertical_gradient</b>)
1285up to the top boundary or up to the next height level defined
1286by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>.
1287A total of 10 different gradients for 11 height intervals (10 intervals
1288if <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>(1)
1289= <i>0.0</i>) can be assigned. The surface temperature is
1290assigned via <a href="#pt_surface">pt_surface</a>.&nbsp;
1291</p> <p>Example:&nbsp; </p> <ul> <p><b>pt_vertical_gradient</b>
1292= <i>1.0</i>, <i>0.5</i>,&nbsp; <br>
1293<b>pt_vertical_gradient_level</b> = <i>500.0</i>,
1294<i>1000.0</i>,</p> </ul> <p>That
1295defines the temperature profile to be neutrally
1297up to z = 500.0 m with a temperature given by <a href="#pt_surface">pt_surface</a>.
1298For 500.0 m &lt; z &lt;= 1000.0 m the temperature gradient is
12991.0 K /
1300100 m and for z &gt; 1000.0 m up to the top boundary it is
13010.5 K / 100 m (it is assumed that the assigned height levels correspond
1302with uv levels). </p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient_level"></a><b>pt_vertical_gradient</b>
1303<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>&nbsp;
1304<span style="font-style: italic;">0.0</span><br>
1305</p> </td> <td style="vertical-align: top;">
1306<p>Height level from which on the temperature gradient defined by
1307<a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1308is effective (in m).&nbsp; </p> <p>The height levels
1309are to be assigned in ascending order. The
1310default values result in a neutral stratification regardless of the
1311values of <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1312(unless the top boundary of the model is higher than 100000.0 m).
1313For the piecewise construction of temperature profiles see <a href="#pt_vertical_gradient">pt_vertical_gradient</a>.</p>
1314</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface"></a><b>q_surface</b></p>
1315</td> <td style="vertical-align: top;">R</td>
1316<td style="vertical-align: top;"><i>0.0</i></td>
1317<td style="vertical-align: top;"> <p>Surface
1318specific humidity / total water content (kg/kg).&nbsp; </p> <p>This
1319parameter assigns the value of the specific humidity q at
1320the surface (k=0).&nbsp; Starting from this value, the initial
1322profile is constructed with&nbsp; <a href="#q_vertical_gradient">q_vertical_gradient</a>
1323and <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
1324This profile is also used for the 1d-model as a stationary profile.</p>
1325</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface_initial_change"></a><b>q_surface_initial</b>
1326<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R<br> </td> <td style="vertical-align: top;"><i>0.0</i></td>
1327<td style="vertical-align: top;"> <p>Change in
1328surface specific humidity / total water content to
1329be made at the beginning
1330of the 3d run (kg/kg).&nbsp; </p> <p>If <b>q_surface_initial_change</b><i>
1331</i>is set to a
1332non-zero value the
1333near surface latent heat flux (water flux) is not allowed to be given
1334simultaneously (see <a href="#surface_waterflux">surface_waterflux</a>).</p>
1335</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient"></a><b>q_vertical_gradient</b></p>
1336</td> <td style="vertical-align: top;">R (10)</td>
1337<td style="vertical-align: top;"><i>10 * 0.0</i></td>
1338<td style="vertical-align: top;"> <p>Humidity
1339gradient(s) of the initial humidity profile
1340(in 1/100 m).&nbsp; </p> <p>This humidity gradient
1341holds starting from the height
1342level&nbsp; defined by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>
1343(precisely: for all uv levels k, where zu(k) &gt;
1345q_init(k) is set: q_init(k) = q_init(k-1) + dzu(k) * <b>q_vertical_gradient</b>)
1346up to the top boundary or up to the next height level defined
1347by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
1348A total of 10 different gradients for 11 height intervals (10 intervals
1349if <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>(1)
1350= <i>0.0</i>) can be asigned. The surface humidity is
1352via <a href="#q_surface">q_surface</a>. </p>
1353<p>Example:&nbsp; </p> <ul> <p><b>q_vertical_gradient</b>
1354= <i>0.001</i>, <i>0.0005</i>,&nbsp; <br>
1355<b>q_vertical_gradient_level</b> = <i>500.0</i>,
1356<i>1000.0</i>,</p> </ul>
1357That defines the humidity to be constant with height up to z =
1359m with a
1360value given by <a href="#q_surface">q_surface</a>.
1361For 500.0 m &lt; z &lt;= 1000.0 m the humidity gradient is
13620.001 / 100
1363m and for z &gt; 1000.0 m up to the top boundary it is
13640.0005 / 100 m (it is assumed that the assigned height levels
1365correspond with uv
1366levels). </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient_level"></a><b>q_vertical_gradient</b>
1367<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>&nbsp;
1368<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
1369which on the moisture gradient defined by <a href="#q_vertical_gradient">q_vertical_gradient</a>
1370is effective (in m).&nbsp; </p> <p>The height levels
1371are to be assigned in ascending order. The
1372default values result in a humidity constant with height regardless of
1373the values of <a href="#q_vertical_gradient">q_vertical_gradient</a>
1374(unless the top boundary of the model is higher than 100000.0 m). For
1375the piecewise construction of humidity profiles see <a href="#q_vertical_gradient">q_vertical_gradient</a>.</p>
1376</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="radiation"></a><b>radiation</b></p>
1377</td> <td style="vertical-align: top;">L</td>
1378<td style="vertical-align: top;"><i>.F.</i></td>
1379<td style="vertical-align: top;"> <p>Parameter to
1380switch on longwave radiation cooling at
1381cloud-tops.&nbsp; </p> <p>Long-wave radiation
1382processes are parameterized by the
1383effective emissivity, which considers only the absorption and emission
1384of long-wave radiation at cloud droplets. The radiation scheme can be
1385used only with <a href="#cloud_physics">cloud_physics</a>
1386= .TRUE. .</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="random_generator"></a><b>random_generator</b></p>
1387</td> <td style="vertical-align: top;">C * 20</td>
1388<td style="vertical-align: top;"> <p><i>'numerical</i><br>
1389<i>recipes'</i></p> </td> <td style="vertical-align: top;"> <p>Random number
1390generator to be used for creating uniformly
1391distributed random numbers. <br> </p> <p>It is
1392used if random perturbations are to be imposed on the
1393velocity field or on the surface heat flux field (see <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>
1394and <a href="chapter_4.2.html#random_heatflux">random_heatflux</a>).
1395By default, the "Numerical Recipes" random number generator is used.
1396This one provides exactly the same order of random numbers on all
1397different machines and should be used in particular for comparison runs.<br>
1399Besides, a system-specific generator is available ( <b>random_generator</b>
1400= <i>'system-specific')</i> which should particularly be
1401used for runs
1402on vector parallel computers (NEC), because the default generator
1403cannot be vectorized and therefore significantly drops down the code
1404performance on these machines.<br> </p> <span style="font-weight: bold;">Note:</span><br>
1405Results from two otherwise identical model runs will not be comparable
1406one-to-one if they used different random number generators.</td> </tr>
1407<tr> <td style="vertical-align: top;"> <p><a name="random_heatflux"></a><b>random_heatflux</b></p>
1408</td> <td style="vertical-align: top;">L</td>
1409<td style="vertical-align: top;"><i>.F.</i></td>
1410<td style="vertical-align: top;"> <p>Parameter to
1411impose random perturbations on the internal two-dimensional near
1412surface heat flux field <span style="font-style: italic;">shf</span>.
1413<br> </p>If a near surface heat flux is used as bottom
1415condition (see <a href="#surface_heatflux">surface_heatflux</a>),
1416it is by default assumed to be horizontally homogeneous. Random
1417perturbations can be imposed on the internal
1418two-dimensional&nbsp;heat flux field <span style="font-style: italic;">shf</span> by assigning <b>random_heatflux</b>
1419= <i>.T.</i>. The disturbed heat flux field is calculated
1421multiplying the
1422values at each mesh point with a normally distributed random number
1423with a mean value and standard deviation of 1. This is repeated after
1424every timestep.<br> <br>
1425In case of a non-flat <a href="#topography">topography</a>,&nbsp;assigning
1427= <i>.T.</i> imposes random perturbations on the
1429flux field <span style="font-style: italic;">shf</span>
1430composed of <a href="#surface_heatflux">surface_heatflux</a>
1431at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
1432at the topography top face.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_max"></a><b>rif_max</b></p>
1433</td> <td style="vertical-align: top;">R</td>
1434<td style="vertical-align: top;"><i>1.0</i></td>
1435<td style="vertical-align: top;"> <p>Upper limit of
1436the flux-Richardson number.&nbsp; </p> <p>With the
1437Prandtl layer switched on (see <a href="#prandtl_layer">prandtl_layer</a>),
1438flux-Richardson numbers (rif) are calculated for z=z<sub>p</sub>
1440in the 3d-model (in the 1d model for all heights). Their values in
1441particular determine the
1442values of the friction velocity (1d- and 3d-model) and the values of
1443the eddy diffusivity (1d-model). With small wind velocities at the
1444Prandtl layer top or small vertical wind shears in the 1d-model, rif
1445can take up unrealistic large values. They are limited by an upper (<span style="font-weight: bold;">rif_max</span>) and lower
1446limit (see <a href="#rif_min">rif_min</a>)
1447for the flux-Richardson number. The condition <b>rif_max</b>
1448&gt; <b>rif_min</b>
1449must be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_min"></a><b>rif_min</b></p>
1450</td> <td style="vertical-align: top;">R</td>
1451<td style="vertical-align: top;"><i>- 5.0</i></td>
1452<td style="vertical-align: top;"> <p>Lower limit of
1453the flux-Richardson number.&nbsp; </p> <p>For further
1454explanations see <a href="#rif_max">rif_max</a>.
1455The condition <b>rif_max</b> &gt; <b>rif_min </b>must
1456be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="roughness_length"></a><b>roughness_length</b></p>
1457</td> <td style="vertical-align: top;">R</td>
1458<td style="vertical-align: top;"><i>0.1</i></td>
1459<td style="vertical-align: top;"> <p>Roughness
1460length (in m).&nbsp; </p> <p>This parameter is
1461effective only in case that a Prandtl layer
1462is switched
1463on (see <a href="#prandtl_layer">prandtl_layer</a>).</p>
1464</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="scalar_advec"></a><b>scalar_advec</b></p>
1465</td> <td style="vertical-align: top;">C * 10</td>
1466<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
1467<td style="vertical-align: top;"> <p>Advection
1468scheme to be used for the scalar quantities.&nbsp; </p> <p>The
1469user can choose between the following schemes:<br> </p> <p><span style="font-style: italic;">'pw-scheme'</span><br>
1470</p> <div style="margin-left: 40px;">The scheme of
1471Piascek and
1472Williams (1970, J. Comp. Phys., 6,
1473392-405) with central differences in the form C3 is used.<br>
1474If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
1475= <span style="font-style: italic;">'leapfrog+euler'</span>
1477advection scheme is - for the Euler-timestep - automatically switched
1478to an upstream-scheme. <br> </div> <br> <p><span style="font-style: italic;">'bc-scheme'</span><br>
1479</p> <div style="margin-left: 40px;">The Bott
1480scheme modified by
1481Chlond (1994, Mon.
1482Wea. Rev., 122, 111-125). This is a conservative monotonous scheme with
1483very small numerical diffusion and therefore very good conservation of
1484scalar flow features. The scheme however, is computationally very
1485expensive both because it is expensive itself and because it does (so
1486far) not allow specific code optimizations (e.g. cache optimization).
1487Choice of this
1488scheme forces the Euler timestep scheme to be used for the scalar
1489quantities. For output of horizontally averaged
1490profiles of the resolved / total heat flux, <a href="chapter_4.2.html#data_output_pr">data_output_pr</a>
1491= <i>'w*pt*BC'</i> / <i>'wptBC' </i>should
1492be used, instead of the
1493standard profiles (<span style="font-style: italic;">'w*pt*'</span>
1494and <span style="font-style: italic;">'wpt'</span>)
1495because these are
1496too inaccurate with this scheme. However, for subdomain analysis (see <a href="#statistic_regions">statistic_regions</a>)
1497exactly the reverse holds: here <i>'w*pt*BC'</i> and <i>'wptBC'</i>
1498show very large errors and should not be used.<br> <br>
1499This scheme is not allowed for non-cyclic lateral boundary conditions
1500(see <a href="#bc_lr">bc_lr</a>
1501and <a href="#bc_ns">bc_ns</a>).<br> <br>
1502</div> <span style="font-style: italic;">'ups-scheme'</span><br>
1503<p style="margin-left: 40px;">The upstream-spline-scheme
1504is used
1505(see Mahrer and Pielke,
15061978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piascek
1507Williams scheme, this is characterized by much better numerical
1508features (less numerical diffusion, better preservation of flux
1509structures, e.g. vortices), but computationally it is much more
1510expensive. In
1511addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
1512= <span style="font-style: italic;">'</span><i>euler'</i>),
1513i.e. the
1514timestep accuracy is only first order. For this reason the advection of
1515momentum (see <a href="#momentum_advec">momentum_advec</a>)
1516should then also be carried out with the upstream-spline scheme,
1517because otherwise the momentum would
1518be subject to large numerical diffusion due to the upstream
1519scheme.&nbsp; </p> <p style="margin-left: 40px;">Since
1520the cubic splines used tend
1521to overshoot under
1522certain circumstances, this effect must be adjusted by suitable
1523filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
1524<a href="#long_filter_factor">long_filter_factor</a>,
1525<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>).
1526This is always neccesssary for runs with stable stratification,
1527even if this stratification appears only in parts of the model
1528domain.&nbsp; </p> <p style="margin-left: 40px;">With
1529stable stratification the
1530upstream-upline scheme also produces gravity waves with large
1531amplitude, which must be
1532suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
1533</p> <p style="margin-left: 40px;"><span style="font-weight: bold;">Important: </span>The&nbsp;
1534upstream-spline scheme is not implemented for humidity and passive
1535scalars (see <a href="#moisture">moisture</a>
1536and <a href="#passive_scalar">passive_scalar</a>)
1537and requires the use of a 2d-domain-decomposition. The last conditions
1538severely restricts code optimization on several machines leading to
1539very long execution times! This scheme is also not allowed for
1540non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
1541and <a href="#bc_ns">bc_ns</a>).</p><br>A
1542differing advection scheme can be choosed for the subgrid-scale TKE
1543using parameter <a href="chapter_4.1.html#use_upstream_for_tke">use_upstream_for_tke</a>.</td>
1544</tr> <tr> <td style="vertical-align: top;">
1545<p><a name="statistic_regions"></a><b>statistic_regions</b></p>
1546</td> <td style="vertical-align: top;">I</td>
1547<td style="vertical-align: top;"><i>0</i></td>
1548<td style="vertical-align: top;"> <p>Number of
1549additional user-defined subdomains for which
1550statistical analysis
1551and corresponding output (profiles, time series) shall be
1552made.&nbsp; </p> <p>By default, vertical profiles and
1553other statistical quantities
1554are calculated as horizontal and/or volume average of the total model
1555domain. Beyond that, these calculations can also be carried out for
1556subdomains which can be defined using the field <a href="chapter_3.5.3.html">rmask </a>within the
1557user-defined software
1558(see <a href="chapter_3.5.3.html">chapter
15593.5.3</a>). The number of these subdomains is determined with the
1560parameter <b>statistic_regions</b>. Maximum 9 additional
1562are allowed. The parameter <a href="chapter_4.3.html#region">region</a>
1563can be used to assigned names (identifier) to these subdomains which
1564are then used in the headers
1565of the output files and plots.</p><p>If the default NetCDF
1566output format is selected (see parameter <a href="chapter_4.2.html#data_output_format">data_output_format</a>),
1567data for the total domain and all defined subdomains are output to the
1568same file(s) (<a href="chapter_3.4.html#DATA_1D_PR_NETCDF">DATA_1D_PR_NETCDF</a>,
1569<a href="chapter_3.4.html#DATA_1D_TS_NETCDF">DATA_1D_TS_NETCDF</a>).
1570In case of <span style="font-weight: bold;">statistic_regions</span>
1571&gt; <span style="font-style: italic;">0</span>,
1572data on the file for the different domains can be distinguished by a
1573suffix which is appended to the quantity names. Suffix 0 means data for
1574the total domain, suffix 1 means data for subdomain 1, etc.</p><p>In
1575case of <span style="font-weight: bold;">data_output_format</span>
1576= <span style="font-style: italic;">'profil'</span>,
1577individual local files for profiles (<a href="chapter_3.4.html#PLOT1D_DATA">PLOT1D_DATA</a>)&nbsp;are
1578created for each subdomain. The individual subdomain files differ by
1579their name (the
1580number of the respective subdomain is attached, e.g.
1581PLOT1D_DATA_1). In this case the name of the file with the data of
1582the total domain is PLOT1D_DATA_0. If no subdomains
1583are declared (<b>statistic_regions</b> = <i>0</i>),
1584the name
1585PLOT1D_DATA is used (this must be considered in the
1586respective file connection statements of the <span style="font-weight: bold;">mrun</span> configuration
1587file).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_heatflux"></a><b>surface_heatflux</b></p>
1588</td> <td style="vertical-align: top;">R</td>
1589<td style="vertical-align: top;"><span style="font-style: italic;">no prescribed<br>
1590heatflux<br> </span></td> <td style="vertical-align: top;"> <p>Kinematic sensible
1591heat flux at the bottom surface (in K m/s).&nbsp; </p> <p>If
1592a value is assigned to this parameter, the internal two-dimensional
1593surface heat flux field <span style="font-style: italic;">shf</span>
1594is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span>&nbsp;as
1595bottom (horizontally homogeneous) boundary condition for the
1596temperature equation. This additionally requires that a Neumann
1597condition must be used for the potential temperature (see <a href="#bc_pt_b">bc_pt_b</a>),
1598because otherwise the resolved scale may contribute to
1599the surface flux so that a constant value cannot be guaranteed. Also,
1600changes of the
1601surface temperature (see <a href="#pt_surface_initial_change">pt_surface_initial_change</a>)
1602are not allowed. The parameter <a href="#random_heatflux">random_heatflux</a>
1603can be used to impose random perturbations on the (homogeneous) surface
1605flux field <span style="font-style: italic;">shf</span>.&nbsp;</p>
1607In case of a non-flat <a href="#topography">topography</a>,&nbsp;the
1608internal two-dimensional&nbsp;surface heat
1609flux field <span style="font-style: italic;">shf</span>
1610is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span>
1611at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
1612at the topography top face.&nbsp;The parameter<a href="#random_heatflux"> random_heatflux</a>
1613can be used to impose random perturbations on this combined surface
1615flux field <span style="font-style: italic;">shf</span>.&nbsp;
1616</p> <p>If no surface heat flux is assigned, <span style="font-style: italic;">shf</span> is calculated
1617at each timestep by u<sub>*</sub> * theta<sub>*</sub>
1618(of course only with <a href="#prandtl_layer">prandtl_layer</a>
1619switched on). Here, u<sub>*</sub>
1620and theta<sub>*</sub> are calculated from the Prandtl law
1622logarithmic wind and temperature
1623profiles between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_pt_b">bc_pt_b</a>)
1624must be used as bottom boundary condition for the potential temperature.</p><p>See
1625also <a href="#top_heatflux">top_heatflux</a>.</p>
1626</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_pressure"></a><b>surface_pressure</b></p>
1627</td> <td style="vertical-align: top;">R</td>
1628<td style="vertical-align: top;"><i>1013.25</i></td>
1629<td style="vertical-align: top;"> <p>Atmospheric
1630pressure at the surface (in hPa).&nbsp; </p>
1631Starting from this surface value, the vertical pressure
1632profile is calculated once at the beginning of the run assuming a
1633neutrally stratified
1634atmosphere. This is needed for
1635converting between the liquid water potential temperature and the
1636potential temperature (see <a href="#cloud_physics">cloud_physics</a><span style="text-decoration: underline;"></span>).</td>
1637</tr> <tr> <td style="vertical-align: top;">
1638<p><a name="surface_scalarflux"></a><b>surface_scalarflux</b></p>
1639</td> <td style="vertical-align: top;">R</td>
1640<td style="vertical-align: top;"><i>0.0</i></td>
1641<td style="vertical-align: top;"> <p>Scalar flux at
1642the surface (in kg/(m<sup>2</sup> s)).&nbsp; </p>
1643<p>If a non-zero value is assigned to this parameter, the
1644respective scalar flux value is used
1645as bottom (horizontally homogeneous) boundary condition for the scalar
1646concentration equation.&nbsp;This additionally requires that a
1648condition must be used for the scalar concentration&nbsp;(see <a href="#bc_s_b">bc_s_b</a>),
1649because otherwise the resolved scale may contribute to
1650the surface flux so that a constant value cannot be guaranteed. Also,
1651changes of the
1652surface scalar concentration (see <a href="#s_surface_initial_change">s_surface_initial_change</a>)
1653are not allowed. <br> </p> <p>If no surface scalar
1654flux is assigned (<b>surface_scalarflux</b>
1655= <i>0.0</i>),
1656it is calculated at each timestep by u<sub>*</sub> * s<sub>*</sub>
1657(of course only with Prandtl layer switched on). Here, s<sub>*</sub>
1658is calculated from the Prandtl law assuming a logarithmic scalar
1660profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_s_b">bc_s_b</a>)
1661must be used as bottom boundary condition for the scalar concentration.</p>
1662</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_waterflux"></a><b>surface_waterflux</b></p>
1663</td> <td style="vertical-align: top;">R</td>
1664<td style="vertical-align: top;"><i>0.0</i></td>
1665<td style="vertical-align: top;"> <p>Kinematic
1666water flux near the surface (in m/s).&nbsp; </p> <p>If
1667a non-zero value is assigned to this parameter, the
1668respective water flux value is used
1669as bottom (horizontally homogeneous) boundary condition for the
1670humidity equation. This additionally requires that a Neumann
1671condition must be used for the specific humidity / total water content
1672(see <a href="#bc_q_b">bc_q_b</a>),
1673because otherwise the resolved scale may contribute to
1674the surface flux so that a constant value cannot be guaranteed. Also,
1675changes of the
1676surface humidity (see <a href="#q_surface_initial_change">q_surface_initial_change</a>)
1677are not allowed.<br> </p> <p>If no surface water
1678flux is assigned (<b>surface_waterflux</b>
1679= <i>0.0</i>),
1680it is calculated at each timestep by u<sub>*</sub> * q<sub>*</sub>
1681(of course only with Prandtl layer switched on). Here, q<sub>*</sub>
1682is calculated from the Prandtl law assuming a logarithmic temperature
1683profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_q_b">bc_q_b</a>)
1684must be used as the bottom boundary condition for the humidity.</p>
1685</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_surface"></a><b>s_surface</b></p>
1686</td> <td style="vertical-align: top;">R</td>
1687<td style="vertical-align: top;"><i>0.0</i></td>
1688<td style="vertical-align: top;"> <p>Surface value
1689of the passive scalar (in kg/m<sup>3</sup>).&nbsp;<br>
1691This parameter assigns the value of the passive scalar s at
1692the surface (k=0)<b>.</b> Starting from this value, the
1693initial vertical scalar concentration profile is constructed with<a href="#s_vertical_gradient">
1694s_vertical_gradient</a> and <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.</td>
1695</tr> <tr> <td style="vertical-align: top;">
1696<p><a name="s_surface_initial_change"></a><b>s_surface_initial</b>
1697<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><i>0.0</i></td>
1698<td style="vertical-align: top;"> <p>Change in
1699surface scalar concentration to be made at the
1700beginning of the 3d run (in kg/m<sup>3</sup>).&nbsp; </p>
1701<p>If <b>s_surface_initial_change</b><i>&nbsp;</i>is
1702set to a
1704value, the near surface scalar flux is not allowed to be given
1705simultaneously (see <a href="#surface_scalarflux">surface_scalarflux</a>).</p>
1706</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient"></a><b>s_vertical_gradient</b></p>
1707</td> <td style="vertical-align: top;">R (10)</td>
1708<td style="vertical-align: top;"><i>10 * 0</i><i>.0</i></td>
1709<td style="vertical-align: top;"> <p>Scalar
1710concentration gradient(s) of the initial scalar
1711concentration profile (in kg/m<sup>3 </sup>/
1712100 m).&nbsp; </p> <p>The scalar gradient holds
1713starting from the height level
1714defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level
1715</a>(precisely: for all uv levels k, where zu(k) &gt;
1716s_vertical_gradient_level, s_init(k) is set: s_init(k) = s_init(k-1) +
1717dzu(k) * <b>s_vertical_gradient</b>) up to the top
1718boundary or up to
1719the next height level defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
1720A total of 10 different gradients for 11 height intervals (10 intervals
1721if <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>(1)
1722= <i>0.0</i>) can be assigned. The surface scalar value is
1724via <a href="#s_surface">s_surface</a>.<br> </p>
1725<p>Example:&nbsp; </p> <ul> <p><b>s_vertical_gradient</b>
1726= <i>0.1</i>, <i>0.05</i>,&nbsp; <br>
1727<b>s_vertical_gradient_level</b> = <i>500.0</i>,
1728<i>1000.0</i>,</p> </ul> <p>That
1729defines the scalar concentration to be constant with
1730height up to z = 500.0 m with a value given by <a href="#s_surface">s_surface</a>.
1731For 500.0 m &lt; z &lt;= 1000.0 m the scalar gradient is 0.1
1732kg/m<sup>3 </sup>/ 100 m and for z &gt; 1000.0 m up to
1733the top
1734boundary it is 0.05 kg/m<sup>3 </sup>/ 100 m (it is
1735assumed that the
1736assigned height levels
1737correspond with uv
1738levels).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient_level"></a><b>s_vertical_gradient_</b>
1739<br> <b>level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>
1740<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
1741which on the scalar gradient defined by <a href="#s_vertical_gradient">s_vertical_gradient</a>
1742is effective (in m).&nbsp; </p> <p>The height levels
1743are to be assigned in ascending order. The
1744default values result in a scalar concentration constant with height
1745regardless of the values of <a href="#s_vertical_gradient">s_vertical_gradient</a>
1746(unless the top boundary of the model is higher than 100000.0 m). For
1748piecewise construction of scalar concentration profiles see <a href="#s_vertical_gradient">s_vertical_gradient</a>.</p>
1749</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="timestep_scheme"></a><b>timestep_scheme</b></p>
1750</td> <td style="vertical-align: top;">C * 20</td>
1751<td style="vertical-align: top;"> <p><i>'runge</i><br>
1752<i>kutta-3'</i></p> </td> <td style="vertical-align: top;"> <p>Time step scheme to
1753be used for the integration of the prognostic
1754variables.&nbsp; </p> <p>The user can choose between
1755the following schemes:<br> </p> <p><span style="font-style: italic;">'runge-kutta-3'</span><br>
1756</p> <div style="margin-left: 40px;">Third order
1757Runge-Kutta scheme.<br>
1758This scheme requires the use of <a href="#momentum_advec">momentum_advec</a>
1759= <a href="#scalar_advec">scalar_advec</a>
1760= '<i>pw-scheme'</i>. Please refer to the&nbsp;<a href="../tec/numerik.heiko/zeitschrittverfahren.pdf">documentation
1761on PALM's time integration schemes&nbsp;(28p., in German)</a>
1762fur further details.<br> </div> <p><span style="font-style: italic;">'runge-kutta-2'</span><br>
1763</p> <div style="margin-left: 40px;">Second order
1764Runge-Kutta scheme.<br>
1765For special features see <b>timestep_scheme</b> = '<i>runge-kutta-3'</i>.<br>
1766</div> <br> <span style="font-style: italic;"><span style="font-style: italic;">'leapfrog'</span><br>
1767<br> </span> <div style="margin-left: 40px;">Second
1768order leapfrog scheme.<br>
1769Although this scheme requires a constant timestep (because it is
1770centered in time),&nbsp; is even applied in case of changes in
1771timestep. Therefore, only small
1772changes of the timestep are allowed (see <a href="#dt">dt</a>).
1773However, an Euler timestep is always used as the first timestep of an
1774initiali run. When using the Bott-Chlond scheme for scalar advection
1775(see <a href="#scalar_advec">scalar_advec</a>),
1776the prognostic equation for potential temperature will be calculated
1777with the Euler scheme, although the leapfrog scheme is switched
1778on.&nbsp; <br>
1779The leapfrog scheme must not be used together with the upstream-spline
1780scheme for calculating the advection (see <a href="#scalar_advec">scalar_advec</a>
1781= '<i>ups-scheme'</i> and <a href="#momentum_advec">momentum_advec</a>
1782= '<i>ups-scheme'</i>).<br> </div> <br>
1783<span style="font-style: italic;">'</span><span style="font-style: italic;"><span style="font-style: italic;">leapfrog+euler'</span><br>
1784<br> </span> <div style="margin-left: 40px;">The
1785leapfrog scheme is used, but
1786after each change of a timestep an Euler timestep is carried out.
1787Although this method is theoretically correct (because the pure
1788leapfrog method does not allow timestep changes), the divergence of the
1789velocity field (after applying the pressure solver) may be
1790significantly larger than with <span style="font-style: italic;">'leapfrog'</span>.<br>
1791</div> <br> <span style="font-style: italic;">'euler'</span><br>
1792<br> <div style="margin-left: 40px;">First order
1793Euler scheme.&nbsp; <br>
1794The Euler scheme must be used when treating the advection terms with
1795the upstream-spline scheme (see <a href="#scalar_advec">scalar_advec</a>
1796= <span style="font-style: italic;">'ups-scheme'</span>
1797and <a href="#momentum_advec">momentum_advec</a>
1798= <span style="font-style: italic;">'ups-scheme'</span>).</div>
1799<br><br>A differing timestep scheme can be choosed for the
1800subgrid-scale TKE using parameter <a href="#use_upstream_for_tke">use_upstream_for_tke</a>.<br>
1801</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>
1802<td style="vertical-align: top;">C * 40</td> <td style="vertical-align: top;"><span style="font-style: italic;">'flat'</span></td> <td>
1803<p>Topography mode.&nbsp; </p> <p>The user can
1804choose between the following modes:<br> </p> <p><span style="font-style: italic;">'flat'</span><br> </p>
1805<div style="margin-left: 40px;">Flat surface.</div> <p><span style="font-style: italic;">'single_building'</span><br>
1806</p> <div style="margin-left: 40px;">Flow
1807around&nbsp;a single rectangular building mounted on a flat surface.<br>
1808The 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>
1809<span style="font-style: italic;"></span> <p><span style="font-style: italic;">'read_from_file'</span><br>
1810</p> <div style="margin-left: 40px;">Flow around
1811arbitrary topography.<br>
1812This 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&nbsp;</font></font><font color="#000000">arbitrary topography </font><font color="#000000"><font color="#000000">height
1813information</font></font><font color="#000000">
1814in m. These data&nbsp;<span style="font-style: italic;"></span>must
1815exactly match the horizontal grid.</font> </div> <span style="font-style: italic;"><br> </span><font color="#000000">
1816Alternatively, the user may add code to the user interface subroutine <a href="chapter_3.5.1.html#user_init_grid">user_init_grid</a>
1817to allow further topography modes.<br> <br>
1818All non-flat <span style="font-weight: bold;">topography</span>
1819modes </font>require the use of <a href="#momentum_advec">momentum_advec</a>
1820= <a href="#scalar_advec">scalar_advec</a>
1821= '<i>pw-scheme'</i>, <a href="chapter_4.2.html#psolver">psolver</a>
1822= <i>'poisfft'</i> or '<i>poisfft_hybrid'</i>,
1823<i>&nbsp;</i><a href="#alpha_surface">alpha_surface</a>
1824= 0.0, <a href="#bc_lr">bc_lr</a> = <a href="#bc_ns">bc_ns</a> = <span style="font-style: italic;">'cyclic'</span>,&nbsp;<a style="" href="#galilei_transformation">galilei_transformation</a>
1825= <span style="font-style: italic;">.F.</span>,&nbsp;<a href="#cloud_physics">cloud_physics&nbsp;</a> = <span style="font-style: italic;">.F.</span>,&nbsp; <a href="#cloud_droplets">cloud_droplets</a> = <span style="font-style: italic;">.F.</span>,&nbsp; <a href="#moisture">moisture</a> = <span style="font-style: italic;">.F.</span>, and <a href="#prandtl_layer">prandtl_layer</a> = .T..<br>
1826<font color="#000000"><br>
1827Note 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
1828nonzero </font><a href="#alpha_surface">alpha_surface</a>.</td>
1829</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>
1830heatflux</span></td><td style="vertical-align: top;"><p>Kinematic
1831sensible heat flux at the top boundary (in K m/s).&nbsp; </p>
1832<p>If a value is assigned to this parameter, the internal
1833two-dimensional surface heat flux field <span style="font-family: monospace;">tswst</span> is
1834initialized with the value of <span style="font-weight: bold;">top_heatflux</span>&nbsp;as
1835top (horizontally homogeneous) boundary condition for the
1836temperature equation. This additionally requires that a Neumann
1837condition must be used for the potential temperature (see <a href="chapter_4.1.html#bc_pt_t">bc_pt_t</a>),
1838because otherwise the resolved scale may contribute to
1839the top flux so that a constant value cannot be guaranteed.<span style="font-style: italic;"></span>&nbsp;</p>
1840<p><span style="font-weight: bold;">Note:</span><br>The
1841application of a top heat flux additionally requires the setting of
1842initial parameter <a href="#use_top_fluxes">use_top_fluxes</a>
1843= .T..<span style="font-style: italic;"></span><span style="font-weight: bold;"></span> </p><p>No
1844Prandtl-layer is available at the top boundary so far.</p><p>See
1845also <a href="#surface_heatflux">surface_heatflux</a>.</p>
1846</td></tr><tr> <td style="vertical-align: top;">
1847<p><a name="ug_surface"></a><span style="font-weight: bold;">ug_surface</span></p>
1848</td> <td style="vertical-align: top;">R<br> </td>
1849<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
1850<td style="vertical-align: top;">u-component of the
1852wind at the surface (in m/s).<br> <br>
1853This parameter assigns the value of the u-component of the geostrophic
1854wind (ug) at the surface (k=0). Starting from this value, the initial
1855vertical profile of the <br>
1856u-component of the geostrophic wind is constructed with <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
1857and <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
1859profile constructed in that way is used for creating the initial
1860vertical velocity profile of the 3d-model. Either it is applied, as it
1861has been specified by the user (<a href="#initializing_actions">initializing_actions</a>
1862= 'set_constant_profiles') or it is used for calculating a stationary
1863boundary layer wind profile (<a href="#initializing_actions">initializing_actions</a>
1864= 'set_1d-model_profiles'). If ug is constant with height (i.e. ug(k)=<span style="font-weight: bold;">ug_surface</span>)
1865and&nbsp; has a large
1866value, it is recommended to use a Galilei-transformation of the
1867coordinate system, if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
1868in order to obtain larger time steps.<br> </td> </tr>
1869<tr> <td style="vertical-align: top;"> <p><a name="ug_vertical_gradient"></a><span style="font-weight: bold;">ug_vertical_gradient</span></p>
1870</td> <td style="vertical-align: top;">R(10)<br>
1871</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
1872* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
1873profile of the&nbsp; u-component of the geostrophic wind (in
18741/100s).<br> <br>
1875The gradient holds starting from the height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
1876(precisely: for all uv levels k where zu(k) &gt; <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>,
1877ug(k) is set: ug(k) = ug(k-1) + dzu(k) * <span style="font-weight: bold;">ug_vertical_gradient</span>)
1878up to the top
1879boundary or up to the next height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
1881total of 10 different gradients for 11 height intervals (10
1882intervals&nbsp; if <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>(1)
1883= 0.0) can be assigned. The surface geostrophic wind is assigned by <a href="#ug_surface">ug_surface</a>. <br> </td>
1884</tr> <tr> <td style="vertical-align: top;">
1885<p><a name="ug_vertical_gradient_level"></a><span style="font-weight: bold;">ug_vertical_gradient_level</span></p>
1886</td> <td style="vertical-align: top;">R(10)<br>
1887</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
1888* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
1889gradient defined by <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
1890is effective (in m).<br> <br>
1891The height levels are to be assigned in ascending order. For the
1892piecewise construction of a profile of the u-component of the
1893geostrophic wind component (ug) see <a href="#ug_vertical_gradient">ug_vertical_gradient</a>.<br>
1894</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_e"></a><b>ups_limit_e</b></p>
1895</td> <td style="vertical-align: top;">R</td>
1896<td style="vertical-align: top;"><i>0.0</i></td>
1897<td style="vertical-align: top;"> <p>Subgrid-scale
1898turbulent kinetic energy difference used as
1899criterion for applying the upstream scheme when upstream-spline
1900advection is switched on (in m<sup>2</sup>/s<sup>2</sup>).
1901&nbsp; </p> <p>This variable steers the appropriate
1902treatment of the
1903advection of the subgrid-scale turbulent kinetic energy in case that
1904the uptream-spline scheme is used . For further information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp; </p>
1905<p>Only positive values are allowed for <b>ups_limit_e</b>.
1906</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_pt"></a><b>ups_limit_pt</b></p>
1907</td> <td style="vertical-align: top;">R</td>
1908<td style="vertical-align: top;"><i>0.0</i></td>
1909<td style="vertical-align: top;"> <p>Temperature
1910difference used as criterion for applying&nbsp;
1911the upstream scheme when upstream-spline advection&nbsp; is
1912switched on
1913(in K).&nbsp; </p> <p>This criterion is used if the
1914upstream-spline scheme is
1915switched on (see <a href="#scalar_advec">scalar_advec</a>).<br>
1916If, for a given gridpoint, the absolute temperature difference with
1917respect to the upstream
1918grid point is smaller than the value given for <b>ups_limit_pt</b>,
1919the upstream scheme is used for this gridpoint (by default, the
1920upstream-spline scheme is always used). Reason: in case of a very small
1921upstream gradient, the advection should cause only a very small
1922tendency. However, in such situations the upstream-spline scheme may
1923give wrong tendencies at a
1924grid point due to spline overshooting, if simultaneously the downstream
1925gradient is very large. In such cases it may be more reasonable to use
1926the upstream scheme. The numerical diffusion caused by the upstream
1927schme remains small as long as the upstream gradients are small.<br>
1928</p> <p>The percentage of grid points for which the
1930scheme is actually used, can be output as a time series with respect to
1932three directions in space with run parameter (see <a href="chapter_4.2.html#dt_dots">dt_dots</a>, the
1933timeseries names in the NetCDF file are <i>'splptx'</i>, <i>'splpty'</i>,
1934<i>'splptz'</i>). The percentage
1935of gridpoints&nbsp; should stay below a certain limit, however, it
1937not possible to give
1938a general limit, since it depends on the respective flow.&nbsp; </p>
1939<p>Only positive values are permitted for <b>ups_limit_pt</b>.<br>
1941A more effective control of
1942the &ldquo;overshoots&rdquo; can be achieved with parameter <a href="#cut_spline_overshoot">cut_spline_overshoot</a>.
1943</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_u"></a><b>ups_limit_u</b></p>
1944</td> <td style="vertical-align: top;">R</td>
1945<td style="vertical-align: top;"><i>0.0</i></td>
1946<td style="vertical-align: top;"> <p>Velocity
1947difference (u-component) used as criterion for
1948applying the upstream scheme
1949when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1950<p>This variable steers the appropriate treatment of the
1951advection of the u-velocity-component in case that the upstream-spline
1952scheme is used. For further
1953information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1954</p> <p>Only positive values are permitted for <b>ups_limit_u</b>.</p>
1955</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_v"></a><b>ups_limit_v</b></p>
1956</td> <td style="vertical-align: top;">R</td>
1957<td style="vertical-align: top;"><i>0.0</i></td>
1958<td style="vertical-align: top;"> <p>Velocity
1959difference (v-component) used as criterion for
1960applying the upstream scheme
1961when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1962<p>This variable steers the appropriate treatment of the
1963advection of the v-velocity-component in case that the upstream-spline
1964scheme is used. For further
1965information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1966</p> <p>Only positive values are permitted for <b>ups_limit_v</b>.</p>
1967</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_w"></a><b>ups_limit_w</b></p>
1968</td> <td style="vertical-align: top;">R</td>
1969<td style="vertical-align: top;"><i>0.0</i></td>
1970<td style="vertical-align: top;"> <p>Velocity
1971difference (w-component) used as criterion for
1972applying the upstream scheme
1973when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1974<p>This variable steers the appropriate treatment of the
1975advection of the w-velocity-component in case that the upstream-spline
1976scheme is used. For further
1977information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1978</p> <p>Only positive values are permitted for <b>ups_limit_w</b>.</p>
1979</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="use_surface_fluxes"></a><b>use_surface_fluxes</b></p>
1980</td> <td style="vertical-align: top;">L</td>
1981<td style="vertical-align: top;"><i>.F.</i></td>
1982<td style="vertical-align: top;"> <p>Parameter to
1983steer the treatment of the subgrid-scale vertical
1984fluxes within the diffusion terms at k=1 (bottom boundary).<br> </p>
1985<p>By default, the near-surface subgrid-scale fluxes are
1986parameterized (like in the remaining model domain) using the gradient
1987approach. If <b>use_surface_fluxes</b>
1988= <i>.TRUE.</i>, the user-assigned surface fluxes are used
1990(see <a href="#surface_heatflux">surface_heatflux</a>,
1991<a href="#surface_waterflux">surface_waterflux</a>
1992and <a href="#surface_scalarflux">surface_scalarflux</a>)
1993<span style="font-weight: bold;">or</span> the
1994surface fluxes are
1995calculated via the Prandtl layer relation (depends on the bottom
1996boundary conditions, see <a href="#bc_pt_b">bc_pt_b</a>,
1997<a href="#bc_q_b">bc_q_b</a>
1998and <a href="#bc_s_b">bc_s_b</a>).<br> </p>
2000is automatically set <i>.TRUE.</i>, if a Prandtl layer is
2001used (see <a href="#prandtl_layer">prandtl_layer</a>).&nbsp;
2002</p> <p>The user may prescribe the surface fluxes at the
2004boundary without using a Prandtl layer by setting <span style="font-weight: bold;">use_surface_fluxes</span> =
2005<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
2006case, the
2007momentum flux (u<sub>*</sub><sup>2</sup>)
2008should also be prescribed,
2009the user must assign an appropriate value within the user-defined code.</p>
2010</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
2011the treatment of the subgrid-scale vertical
2012fluxes within the diffusion terms at k=nz (top boundary).</p><p>By
2013default, the fluxes at nz are calculated using the gradient approach.
2014If <b>use_top_fluxes</b>
2015= <i>.TRUE.</i>, the user-assigned top fluxes are used
2017(see <a href="chapter_4.1.html#top_heatflux">top_heatflux</a>).</p><p>Currently,
2018only a value for the sensible 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
2019heat flux at the top will be automatically set to zero.</p></td></tr><tr>
2020<td style="vertical-align: top;"> <p><a name="use_ug_for_galilei_tr"></a><b>use_ug_for_galilei_tr</b></p>
2021</td> <td style="vertical-align: top;">L</td>
2022<td style="vertical-align: top;"><i>.T.</i></td>
2023<td style="vertical-align: top;"> <p>Switch to
2024determine the translation velocity in case that a
2025Galilean transformation is used.<br> </p> <p>In
2026case of a Galilean transformation (see <a href="#galilei_transformation">galilei_transformation</a>),
2028= <i>.T.</i>&nbsp; ensures
2029that the coordinate system is translated with the geostrophic windspeed.<br>
2030</p> <p>Alternatively, with <b>use_ug_for_galilei_tr</b>
2031= <i>.F</i>.,
2033geostrophic wind can be replaced as translation speed by the (volume)
2034averaged velocity. However, in this case the user must be aware of fast
2035growing gravity waves, so this
2036choice 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
2037advection/timestep scheme to be used for the subgrid-scale TKE.<br><br>By
2038default, the advection scheme and the timestep scheme to be used for
2039the subgrid-scale TKE are set by the initialization parameters <a href="#scalar_advec">scalar_advec</a> and <a href="#timestep_scheme">timestep_scheme</a>,
2040respectively. <span style="font-weight: bold;">use_upstream_for_tke</span>
2041= <span style="font-style: italic;">.T.</span>
2042forces the Euler-scheme and the upstream-scheme to be used as timestep
2043scheme and advection scheme, respectively. By these methods, the strong
2044(artificial) near-surface vertical gradients of the subgrid-scale TKE
2045are significantly reduced. This is required when subgrid-scale
2046velocities are used for advection of particles (see particle package
2047parameter <a href="chapter_4.2.html#use_sgs_for_particles">use_sgs_for_particles</a>).</td></tr><tr>
2048<td style="vertical-align: top;"> <p><a name="vg_surface"></a><span style="font-weight: bold;">vg_surface</span></p>
2049</td> <td style="vertical-align: top;">R<br> </td>
2050<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
2051<td style="vertical-align: top;">v-component of the
2053wind at the surface (in m/s).<br> <br>
2054This parameter assigns the value of the v-component of the geostrophic
2055wind (vg) at the surface (k=0). Starting from this value, the initial
2056vertical profile of the <br>
2057v-component of the geostrophic wind is constructed with <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
2058and <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
2061constructed in that way is used for creating the initial vertical
2062velocity profile of the 3d-model. Either it is applied, as it has been
2063specified by the user (<a href="#initializing_actions">initializing_actions</a>
2064= 'set_constant_profiles')
2065or it is used for calculating a stationary boundary layer wind profile
2066(<a href="#initializing_actions">initializing_actions</a>
2068'set_1d-model_profiles'). If vg is constant
2069with height (i.e. vg(k)=<span style="font-weight: bold;">vg_surface</span>)
2070and&nbsp; has a large value, it is
2071recommended to use a Galilei-transformation of the coordinate system,
2072if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
2073in order to obtain larger
2074time steps.</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>
2075</td> <td style="vertical-align: top;">R(10)<br>
2076</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
2077* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
2078profile of the&nbsp; v-component of the geostrophic wind (in
20791/100s).<br> <br>
2080The gradient holds starting from the height level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>
2081(precisely: for all uv levels k where zu(k)
2082&gt; <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
2083vg(k) is set: vg(k) = vg(k-1) + dzu(k)
2084* <span style="font-weight: bold;">vg_vertical_gradient</span>)
2085up to
2086the top boundary or up to the next height
2087level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
2088A total of 10 different
2089gradients for 11 height intervals (10 intervals&nbsp; if <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>(1)
20910.0) can be assigned. The surface
2092geostrophic wind is assigned by <a href="#vg_surface">vg_surface</a>.</td>
2093</tr> <tr> <td style="vertical-align: top;">
2094<p><a name="vg_vertical_gradient_level"></a><span style="font-weight: bold;">vg_vertical_gradient_level</span></p>
2095</td> <td style="vertical-align: top;">R(10)<br>
2096</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
2097* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
2098gradient defined by <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
2099is effective (in m).<br> <br>
2100The height levels are to be assigned in ascending order. For the
2101piecewise construction of a profile of the v-component of the
2102geostrophic wind component (vg) see <a href="#vg_vertical_gradient">vg_vertical_gradient</a>.</td>
2103</tr> <tr> <td style="vertical-align: top;">
2104<p><a name="wall_adjustment"></a><b>wall_adjustment</b></p>
2105</td> <td style="vertical-align: top;">L</td>
2106<td style="vertical-align: top;"><i>.T.</i></td>
2107<td style="vertical-align: top;"> <p>Parameter to
2108restrict the mixing length in the vicinity of the
2110boundary.&nbsp; </p> <p>With <b>wall_adjustment</b>
2111= <i>.TRUE., </i>the mixing
2112length is limited to a maximum of&nbsp; 1.8 * z. This condition
2113typically affects only the
2114first grid points above the bottom boundary.</p> </td> </tr>
2115<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="wall_heatflux"></a>wall_heatflux</span></td>
2116<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
2117kinematic sensible heat flux in W m<sup>-2</sup>
2118at the five topography faces:<br> <br> <div style="margin-left: 40px;"><span style="font-weight: bold;">wall_heatflux(0)&nbsp;&nbsp;
2119&nbsp;</span>top face<br> <span style="font-weight: bold;">wall_heatflux(1)&nbsp;&nbsp;&nbsp;
2120</span>left face<br> <span style="font-weight: bold;">wall_heatflux(2)&nbsp;&nbsp;&nbsp;
2121</span>right face<br> <span style="font-weight: bold;">wall_heatflux(3)&nbsp;&nbsp;&nbsp;
2122</span>south face<br> <span style="font-weight: bold;">wall_heatflux(4)&nbsp;&nbsp;&nbsp;
2123</span>north face</div> <br>
2124This parameter applies only in case of a non-flat <a href="#topography">topography</a>.&nbsp;The
2125parameter <a href="#random_heatflux">random_heatflux</a>
2126can be used to impose random perturbations on the internal
2127two-dimensional surface heat
2128flux field <span style="font-style: italic;">shf</span>
2129that is composed of <a href="#surface_heatflux">surface_heatflux</a>
2130at the bottom surface and <span style="font-weight: bold;">wall_heatflux(0)</span>
2131at the topography top face.&nbsp;</td> </tr> </tbody>
2133<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>
2134<p style="line-height: 100%;"><i>Last
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