source: palm/tags/release-3.2a/DOC/app/chapter_4.1.html

Last change on this file was 83, checked in by raasch, 15 years ago

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PALM can be generally installed on any kind of Linux-, IBM-AIX-, or NEC-SX-system by adding appropriate settings to the configuration file.

Scripts are also running under the public domain ksh.

All system relevant compile and link options as well as the host identifier (local_host) are specified in the configuration file.

Filetransfer by ftp removed (options -f removed from mrun and mbuild).

Call of (system-)FLUSH routine moved to new routine local_flush.

return_addres and return_username are read from ENVPAR-NAMELIST-file instead of using local_getenv.

Preprocessor strings for different linux clusters changed to "lc", some preprocessor directives renamed (new: intel_openmp_bug), preprocessor directives for old systems removed

advec_particles, check_open, cpu_log, cpu_statistics, data_output_dvrp, flow_statistics, header, init_dvrp, init_particles, init_1d_model, init_dvrp, init_pegrid, local_getenv, local_system, local_tremain, local_tremain_ini, modules, palm, parin, run_control

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mbuild, mrun

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1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
2<html><head>
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="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/PALM_group.html#0">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>.
66<b>bc_e_b</b>
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/radiation'</span>
91(inflow from left, outflow to the right) or <span style="font-style: italic;">'radiation/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="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">psolver</a>)
95and it also requires cyclic boundary conditions along y (see&nbsp;<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 radiation condition is used for all velocity components, while a Neumann (zero
101gradient) condition is used for the scalars. For perturbation
102pressure Neumann (zero gradient) conditions are assumed both at the
103inflow and at the outflow.<br> <br>
104When using non-cyclic lateral boundaries, a filter is applied to the
105velocity field in the vicinity of the outflow in order to suppress any
106reflections of outgoing disturbances (see <a href="#km_damp_max">km_damp_max</a>
107and <a href="#outflow_damping_width">outflow_damping_width</a>).<br>
108<br>
109In order to maintain a turbulent state of the flow, it may be
110neccessary to continuously impose perturbations on the horizontal
111velocity field in the vicinity of the inflow throughout the whole run.
112This can be switched on using <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#create_disturbances">create_disturbances</a>.
113The horizontal range to which these perturbations are applied is
114controlled by the parameters <a href="#inflow_disturbance_begin">inflow_disturbance_begin</a>
115and <a href="#inflow_disturbance_end">inflow_disturbance_end</a>.
116The vertical range and the perturbation amplitude are given by <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_level_b</a>,
117<a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_level_t</a>,
118and <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">disturbance_amplitude</a>.
119The time interval at which perturbations are to be imposed is set by <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#dt_disturb">dt_disturb</a>.<br>
120<br>
121In case of non-cyclic horizontal boundaries <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#call_psolver_at_all_substeps">call_psolver
122at_all_substeps</a> = .T. should be used.<br> <br> <span style="font-weight: bold;">Note:</span><br>
123Using non-cyclic lateral boundaries requires very sensitive adjustments
124of the inflow (vertical profiles) and the bottom boundary conditions,
125e.g. a surface heating should not be applied near the inflow boundary
126because this may significantly disturb the inflow. Please check the
127model results very carefully.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_ns"></a><b>bc_ns</b></p>
128</td> <td style="vertical-align: top;">C * 20</td>
129<td style="vertical-align: top;"><span style="font-style: italic;">'cyclic'</span></td>
130<td style="vertical-align: top;">Boundary
131condition along y (for all quantities).<br> <br>
132By default, a cyclic boundary condition is used along y.<br> <br>
133<span style="font-weight: bold;">bc_ns</span> may
134also be
135assigned the values <span style="font-style: italic;">'dirichlet/radiation'</span>
136(inflow from rear ("north"), outflow to the front ("south")) or <span style="font-style: italic;">'radiation/dirichlet'</span>
137(inflow from front ("south"), outflow to the rear ("north")). This
138requires the multi-grid
139method to be used for solving the Poisson equation for perturbation
140pressure (see <a href="chapter_4.2.html#psolver">psolver</a>)
141and it also requires cyclic boundary conditions along x (see<br> <a href="#bc_lr">bc_lr</a>).<br> <br>
142In case of these non-cyclic lateral boundaries, a Dirichlet condition
143is used at the inflow for all quantities (initial vertical profiles -
144see <a href="chapter_4.1.html#initializing_actions">initializing_actions</a>
145- are fixed during the run) except u, to which a Neumann (zero
146gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components, while a Neumann (zero
147gradient) condition is used for the scalars. For perturbation
148pressure Neumann (zero gradient) conditions are assumed both at the
149inflow and at the outflow.<br> <br>
150For further details regarding non-cyclic lateral boundary conditions
151see <a href="#bc_lr">bc_lr</a>.</td> </tr>
152<tr> <td style="vertical-align: top;"> <p><a name="bc_p_b"></a><b>bc_p_b</b></p> </td>
153<td style="vertical-align: top;">C * 20</td> <td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
154<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
155perturbation pressure.&nbsp; </p> <p>Allowed values
156are <span style="font-style: italic;">'dirichlet'</span>,
157<span style="font-style: italic;">'neumann'</span>
158and <span style="font-style: italic;">'neumann+inhomo'</span>.&nbsp;
159<span style="font-style: italic;">'dirichlet'</span>
160sets
161p(k=0)=0.0,&nbsp; <span style="font-style: italic;">'neumann'</span>
162sets p(k=0)=p(k=1). <span style="font-style: italic;">'neumann+inhomo'</span>
163corresponds to an extended Neumann boundary condition where heat flux
164or temperature inhomogeneities near the
165surface (pt(k=1))&nbsp; are additionally regarded (see Shen and
166LeClerc
167(1995, Q.J.R. Meteorol. Soc.,
1681209)). This condition is only permitted with the Prandtl-layer
169switched on (<a href="#prandtl_layer">prandtl_layer</a>),
170otherwise the run is terminated.&nbsp; </p> <p>Since
171at the bottom boundary of the model the vertical
172velocity
173disappears (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>)
174dp/dz = 0 should
175be used, which leaves the vertical component w unchanged when the
176pressure solver is applied. Simultaneous use of the Neumann boundary
177conditions both at the bottom and at the top boundary (<a href="#bc_p_t">bc_p_t</a>)
178usually yields no consistent solution for the perturbation pressure and
179should be avoided.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_p_t"></a><b>bc_p_t</b></p>
180</td> <td style="vertical-align: top;">C * 20</td>
181<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
182<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
183perturbation pressure.&nbsp; </p> <p style="font-style: normal;">Allowed values are <span style="font-style: italic;">'dirichlet'</span>
184(p(k=nz+1)= 0.0) or <span style="font-style: italic;">'neumann'</span>
185(p(k=nz+1)=p(k=nz)).&nbsp; </p> <p>Simultaneous use
186of Neumann boundary conditions both at the
187top and bottom boundary (<a href="#bc_p_b">bc_p_b</a>)
188usually yields no consistent solution for the perturbation pressure and
189should be avoided. Since at the bottom boundary the Neumann
190condition&nbsp; is a good choice (see <a href="#bc_p_b">bc_p_b</a>),
191a Dirichlet condition should be set at the top boundary.</p> </td>
192</tr> <tr> <td style="vertical-align: top;">
193<p><a name="bc_pt_b"></a><b>bc_pt_b</b></p>
194</td> <td style="vertical-align: top;">C*20</td>
195<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
196<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
197potential temperature.&nbsp; </p> <p>Allowed values
198are <span style="font-style: italic;">'dirichlet'</span>
199(pt(k=0) = const. = <a href="#pt_surface">pt_surface</a>
200+ <a href="#pt_surface_initial_change">pt_surface_initial_change</a>;
201the user may change this value during the run using user-defined code)
202and <span style="font-style: italic;">'neumann'</span>
203(pt(k=0)=pt(k=1)).&nbsp; <br>
204When a constant surface sensible heat flux is used (<a href="#surface_heatflux">surface_heatflux</a>), <b>bc_pt_b</b>
205= <span style="font-style: italic;">'neumann'</span>
206must be used, because otherwise the resolved scale may contribute to
207the surface flux so that a constant value cannot be guaranteed.</p>
208</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pc_pt_t"></a><b>bc_pt_t</b></p>
209</td> <td style="vertical-align: top;">C * 20</td>
210<td style="vertical-align: top;"><span style="font-style: italic;">'initial gradient'</span></td>
211<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
212potential temperature.&nbsp; </p> <p>Allowed are the
213values <span style="font-style: italic;">'dirichlet' </span>(pt(k=nz+1)
214does not change during the run), <span style="font-style: italic;">'neumann'</span>
215(pt(k=nz+1)=pt(k=nz)), and <span style="font-style: italic;">'initial_gradient'</span>.
216With the 'initial_gradient'-condition the value of the temperature
217gradient at the top is
218calculated from the initial
219temperature profile (see <a href="#pt_surface">pt_surface</a>,
220<a href="#pt_vertical_gradient">pt_vertical_gradient</a>)
221by bc_pt_t_val = (pt_init(k=nz+1) -
222pt_init(k=nz)) / dzu(nz+1).<br>
223Using this value (assumed constant during the
224run) the temperature boundary values are calculated as&nbsp; </p>
225<ul> <p style="font-style: normal;">pt(k=nz+1) =
226pt(k=nz) +
227bc_pt_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up to k=nz the prognostic
228equation for the temperature is solved).<br>
229When a constant sensible heat flux is used at the top boundary (<a href="chapter_4.1.html#top_heatflux">top_heatflux</a>),
230<b>bc_pt_t</b> = <span style="font-style: italic;">'neumann'</span>
231must be used, because otherwise the resolved scale may contribute to
232the top flux so that a constant value cannot be guaranteed.</p> </td>
233</tr> <tr> <td style="vertical-align: top;">
234<p><a name="bc_q_b"></a><b>bc_q_b</b></p>
235</td> <td style="vertical-align: top;">C * 20</td>
236<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
237<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
238specific humidity / total water content.&nbsp; </p> <p>Allowed
239values are <span style="font-style: italic;">'dirichlet'</span>
240(q(k=0) = const. = <a href="#q_surface">q_surface</a>
241+ <a href="#q_surface_initial_change">q_surface_initial_change</a>;
242the user may change this value during the run using user-defined code)
243and <span style="font-style: italic;">'neumann'</span>
244(q(k=0)=q(k=1)).&nbsp; <br>
245When a constant surface latent heat flux is used (<a href="#surface_waterflux">surface_waterflux</a>), <b>bc_q_b</b>
246= <span style="font-style: italic;">'neumann'</span>
247must be used, because otherwise the resolved scale may contribute to
248the surface flux so that a constant value cannot be guaranteed.</p>
249</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_q_t"></a><b>bc_q_t</b></p>
250</td> <td style="vertical-align: top;"><span style="font-style: italic;">C
251* 20</span></td> <td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
252<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
253specific humidity / total water content.&nbsp; </p> <p>Allowed
254are the values <span style="font-style: italic;">'dirichlet'</span>
255(q(k=nz) and q(k=nz+1) do
256not change during the run) and <span style="font-style: italic;">'neumann'</span>.
257With the Neumann boundary
258condition the value of the humidity gradient at the top is calculated
259from the
260initial humidity profile (see <a href="#q_surface">q_surface</a>,
261<a href="#q_vertical_gradient">q_vertical_gradient</a>)
262by: bc_q_t_val = ( q_init(k=nz) - q_init(k=nz-1)) / dzu(nz).<br>
263Using this value (assumed constant during the run) the humidity
264boundary values
265are calculated as&nbsp; </p> <ul> <p style="font-style: normal;">q(k=nz+1) =q(k=nz) +
266bc_q_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up tp k=nz the prognostic
267equation for q is solved). </p> </td> </tr> <tr>
268<td style="vertical-align: top;"> <p><a name="bc_s_b"></a><b>bc_s_b</b></p> </td>
269<td style="vertical-align: top;">C * 20</td> <td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
270<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
271scalar concentration.&nbsp; </p> <p>Allowed values
272are <span style="font-style: italic;">'dirichlet'</span>
273(s(k=0) = const. = <a href="#s_surface">s_surface</a>
274+ <a href="#s_surface_initial_change">s_surface_initial_change</a>;
275the user may change this value during the run using user-defined code)
276and <span style="font-style: italic;">'neumann'</span>
277(s(k=0) =
278s(k=1)).&nbsp; <br>
279When a constant surface concentration flux is used (<a href="#surface_scalarflux">surface_scalarflux</a>), <b>bc_s_b</b>
280= <span style="font-style: italic;">'neumann'</span>
281must be used, because otherwise the resolved scale may contribute to
282the surface flux so that a constant value cannot be guaranteed.</p>
283</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_s_t"></a><b>bc_s_t</b></p>
284</td> <td style="vertical-align: top;">C * 20</td>
285<td style="vertical-align: top;"><span style="font-style: italic;">'neumann'</span></td>
286<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
287scalar concentration.&nbsp; </p> <p>Allowed are the
288values <span style="font-style: italic;">'dirichlet'</span>
289(s(k=nz) and s(k=nz+1) do
290not change during the run) and <span style="font-style: italic;">'neumann'</span>.
291With the Neumann boundary
292condition the value of the scalar concentration gradient at the top is
293calculated
294from the initial scalar concentration profile (see <a href="#s_surface">s_surface</a>, <a href="#s_vertical_gradient">s_vertical_gradient</a>)
295by: bc_s_t_val = (s_init(k=nz) - s_init(k=nz-1)) / dzu(nz).<br>
296Using this value (assumed constant during the run) the concentration
297boundary values
298are calculated as </p> <ul> <p style="font-style: normal;">s(k=nz+1) = s(k=nz) +
299bc_s_t_val * dzu(nz+1)</p> </ul> <p style="font-style: normal;">(up to k=nz the prognostic
300equation for the scalar concentration is
301solved).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_uv_b"></a><b>bc_uv_b</b></p>
302</td> <td style="vertical-align: top;">C * 20</td>
303<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
304<td style="vertical-align: top;"> <p style="font-style: normal;">Bottom boundary condition of the
305horizontal velocity components u and v.&nbsp; </p> <p>Allowed
306values are <span style="font-style: italic;">'dirichlet' </span>and
307<span style="font-style: italic;">'neumann'</span>. <b>bc_uv_b</b>
308= <span style="font-style: italic;">'dirichlet'</span>
309yields the
310no-slip condition with u=v=0 at the bottom. Due to the staggered grid
311u(k=0) and v(k=0) are located at z = - 0,5 * <a href="#dz">dz</a>
312(below the bottom), while u(k=1) and v(k=1) are located at z = +0,5 *
313dz. u=v=0 at the bottom is guaranteed using mirror boundary
314condition:&nbsp; </p> <ul> <p style="font-style: normal;">u(k=0) = - u(k=1) and v(k=0) = -
315v(k=1)</p> </ul> <p style="font-style: normal;">The
316Neumann boundary condition
317yields the free-slip condition with u(k=0) = u(k=1) and v(k=0) =
318v(k=1).
319With Prandtl - layer switched on, the free-slip condition is not
320allowed (otherwise the run will be terminated)<font color="#000000">.</font></p>
321</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="bc_uv_t"></a><b>bc_uv_t</b></p>
322</td> <td style="vertical-align: top;">C * 20</td>
323<td style="vertical-align: top;"><span style="font-style: italic;">'dirichlet'</span></td>
324<td style="vertical-align: top;"> <p style="font-style: normal;">Top boundary condition of the
325horizontal velocity components u and v.&nbsp; </p> <p>Allowed
326values are <span style="font-style: italic;">'dirichlet'</span>
327and <span style="font-style: italic;">'neumann'</span>.
328The
329Dirichlet condition yields u(k=nz+1) = ug(nz+1) and v(k=nz+1) =
330vg(nz+1),
331Neumann condition yields the free-slip condition with u(k=nz+1) =
332u(k=nz) and v(k=nz+1) = v(k=nz) (up to k=nz the prognostic equations
333for the velocities are solved).</p> </td> </tr> <tr>
334<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_height"></a>building_height</span></td>
335<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">50.0</span></td> <td>Height
336of a single building in m.<br> <br> <span style="font-weight: bold;">building_height</span> must
337be less than the height of the model domain. This parameter requires
338the use of&nbsp;<a href="#topography">topography</a>
339= <span style="font-style: italic;">'single_building'</span>.</td>
340</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_length_x"></a>building_length_x</span></td>
341<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
342building in m.<br> <br>
343Currently, <span style="font-weight: bold;">building_length_x</span>
344must be at least <span style="font-style: italic;">3
345*&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>
346</span><span style="font-style: italic;">- <a href="#building_wall_left">building_wall_left</a></span>.
347This parameter requires the use of&nbsp;<a href="#topography">topography</a>
348= <span style="font-style: italic;">'single_building'</span>.</td>
349</tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_length_y"></a>building_length_y</span></td>
350<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">50.0</span></td> <td>Depth
351of a single building in m.<br> <br>
352Currently, <span style="font-weight: bold;">building_length_y</span>
353must be at least <span style="font-style: italic;">3
354*&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
355the 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_wall_left"></a>building_wall_left</span></td>
358<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">building centered in x-direction</span></td>
359<td>x-coordinate of the left building wall (distance between the
360left building wall and the left border of the model domain) in m.<br>
361<br>
362Currently, <span style="font-weight: bold;">building_wall_left</span>
363must be at least <span style="font-style: italic;">1
364*&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;
365- 1 ) * <a href="#dx">dx</a> -&nbsp; <a href="#building_length_x">building_length_x</a></span>.
366This parameter requires the use of&nbsp;<a href="#topography">topography</a>
367= <span style="font-style: italic;">'single_building'</span>.<br>
368<br>
369The default value&nbsp;<span style="font-weight: bold;">building_wall_left</span>
370= <span style="font-style: italic;">( ( <a href="#nx">nx</a>&nbsp;+
3711 ) * <a href="#dx">dx</a> -&nbsp; <a href="#building_length_x">building_length_x</a> ) / 2</span>
372centers the building in x-direction. </td> </tr> <tr>
373<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="building_wall_south"></a>building_wall_south</span></td>
374<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>
375<td>y-coordinate of the South building wall (distance between the
376South building wall and the South border of the model domain) in m.<br>
377<br>
378Currently, <span style="font-weight: bold;">building_wall_south</span>
379must be at least <span style="font-style: italic;">1
380*&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;
381- 1 ) * <a href="#dy">dy</a> -&nbsp; <a href="#building_length_y">building_length_y</a></span>.
382This parameter requires the use of&nbsp;<a href="#topography">topography</a>
383= <span style="font-style: italic;">'single_building'</span>.<br>
384<br>
385The default value&nbsp;<span style="font-weight: bold;">building_wall_south</span>
386= <span style="font-style: italic;">( ( <a href="#ny">ny</a>&nbsp;+
3871 ) * <a href="#dy">dy</a> -&nbsp; <a href="#building_length_y">building_length_y</a> ) / 2</span>
388centers the building in y-direction. </td> </tr> <tr>
389<td style="vertical-align: top;"><span style="font-weight: bold;"><a name="cloud_droplets"></a>cloud_droplets</span><br>
390</td> <td style="vertical-align: top;">L<br> </td>
391<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span><br> </td>
392<td style="vertical-align: top;">Parameter to switch on
393usage of cloud droplets.<br> <br>
394Cloud droplets require to use the particle package (<span style="font-weight: bold;">mrun</span>-option <span style="font-family: monospace;">-p particles</span>),
395so in this case a particle corresponds to a droplet. The droplet
396features (number of droplets, initial radius, etc.) can be steered with
397the&nbsp; respective particle parameters (see e.g. <a href="#chapter_4.2.html#radius">radius</a>).
398The real number of initial droplets in a grid cell is equal to the
399initial 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>
400<span lang="en-GB"><font face="Thorndale, serif">and
401</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>)
402times the <a href="#initial_weighting_factor">initial_weighting_factor</a>.<br>
403<br>
404In case of using cloud droplets, the default condensation scheme in
405PALM cannot be used, i.e. <a href="#cloud_physics">cloud_physics</a>
406must be set <span style="font-style: italic;">.F.</span>.<br>
407</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="cloud_physics"></a><b>cloud_physics</b></p>
408</td> <td style="vertical-align: top;">L<br> </td>
409<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p>Parameter to switch
410on the condensation scheme.&nbsp; </p>
411For <b>cloud_physics =</b> <span style="font-style: italic;">.TRUE.</span>, equations
412for the
413liquid water&nbsp;
414content and the liquid water potential temperature are solved instead
415of those for specific humidity and potential temperature. Note
416that a grid volume is assumed to be either completely saturated or
417completely
418unsaturated (0%-or-100%-scheme). A simple precipitation scheme can
419additionally be switched on with parameter <a href="#precipitation">precipitation</a>.
420Also cloud-top cooling by longwave radiation can be utilized (see <a href="#radiation">radiation</a>)<br> <b><br>
421cloud_physics =</b> <span style="font-style: italic;">.TRUE.
422</span>requires&nbsp;<a href="#humidity">humidity</a>
423=<span style="font-style: italic;"> .TRUE.</span> .<br>
424Detailed information about the condensation scheme is given in the
425description of the <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM-1/Dokumentationen/Cloud_physics/wolken.pdf">cloud
426physics module</a> (pdf-file, only in German).<br> <br>
427This condensation scheme is not allowed if cloud droplets are simulated
428explicitly (see <a href="#cloud_droplets">cloud_droplets</a>).<br>
429</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="conserve_volume_flow"></a>conserve_volume_flow</span></td>
430<td style="vertical-align: top;">L</td> <td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td>Conservation
431of volume flow in x- and y-direction.<br> <br> <span style="font-weight: bold;">conserve_volume_flow</span>
432= <span style="font-style: italic;">.TRUE.</span>
433guarantees that the volume flow through the xz- or yz-cross-section of
434the total model domain remains constant (equal to the initial value at
435t=0) throughout the run.<br>
436</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="cut_spline_overshoot"></a><b>cut_spline_overshoot</b></p>
437</td> <td style="vertical-align: top;">L</td>
438<td style="vertical-align: top;"><span style="font-style: italic;">.T.</span></td> <td style="vertical-align: top;"> <p>Cuts off of
439so-called overshoots, which can occur with the
440upstream-spline scheme.&nbsp; </p> <p><font color="#000000">The cubic splines tend to overshoot in
441case of discontinuous changes of variables between neighbouring grid
442points.</font><font color="#ff0000"> </font><font color="#000000">This
443may lead to errors in calculating the advection tendency.</font>
444Choice
445of <b>cut_spline_overshoot</b> = <i>.TRUE.</i>
446(switched on by
447default)
448allows variable values not to exceed an interval defined by the
449respective adjacent grid points. This interval can be adjusted
450seperately for every prognostic variable (see initialization parameters
451<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>,
452etc.). This might be necessary in case that the
453default interval has a non-tolerable effect on the model
454results.&nbsp; </p> <p>Overshoots may also be removed
455using the parameters <a href="#ups_limit_e">ups_limit_e</a>,
456<a href="#ups_limit_pt">ups_limit_pt</a>,
457etc. as well as by applying a long-filter (see <a href="#long_filter_factor">long_filter_factor</a>).</p>
458</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="damp_level_1d"></a><b>damp_level_1d</b></p>
459</td> <td style="vertical-align: top;">R</td>
460<td style="vertical-align: top;"><span style="font-style: italic;">zu(nz+1)</span></td>
461<td style="vertical-align: top;"> <p>Height where
462the damping layer begins in the 1d-model
463(in m).&nbsp; </p> <p>This parameter is used to
464switch on a damping layer for the
4651d-model, which is generally needed for the damping of inertia
466oscillations. Damping is done by gradually increasing the value
467of the eddy diffusivities about 10% per vertical grid level
468(starting with the value at the height given by <b>damp_level_1d</b>,
469or possibly from the next grid pint above), i.e. K<sub>m</sub>(k+1)
470=
4711.1 * K<sub>m</sub>(k).
472The values of K<sub>m</sub> are limited to 10 m**2/s at
473maximum.&nbsp; <br>
474This parameter only comes into effect if the 1d-model is switched on
475for
476the initialization of the 3d-model using <a href="#initializing_actions">initializing_actions</a>
477= <span style="font-style: italic;">'set_1d-model_profiles'</span>.
478<br> </p> </td> </tr> <tr> <td style="vertical-align: top;"><a name="dissipation_1d"></a><span style="font-weight: bold;">dissipation_1d</span><br>
479</td> <td style="vertical-align: top;">C*20<br>
480</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>
481<td style="vertical-align: top;">Calculation method for
482the energy dissipation term in the TKE equation of the 1d-model.<br>
483<br>
484By default the dissipation is calculated as in the 3d-model using diss
485= (0.19 + 0.74 * l / l_grid) * e**1.5 / l.<br> <br>
486Setting <span style="font-weight: bold;">dissipation_1d</span>
487= <span style="font-style: italic;">'detering'</span>
488forces the dissipation to be calculated as diss = 0.064 * e**1.5 / l.<br>
489</td> </tr>
490<tr> <td style="vertical-align: top;"> <p><a name="dt"></a><b>dt</b></p> </td>
491<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">variable</span></td>
492<td style="vertical-align: top;"> <p>Time step for
493the 3d-model (in s).&nbsp; </p> <p>By default, (i.e.
494if a Runge-Kutta scheme is used, see <a href="#timestep_scheme">timestep_scheme</a>)
495the value of the time step is calculating after each time step
496(following the time step criteria) and
497used for the next step.</p> <p>If the user assigns <b>dt</b>
498a value, then the time step is
499fixed to this value throughout the whole run (whether it fulfills the
500time step
501criteria or not). However, changes are allowed for restart runs,
502because <b>dt</b> can also be used as a <a href="chapter_4.2.html#dt_laufparameter">run
503parameter</a>.&nbsp; </p> <p>In case that the
504calculated time step meets the condition<br> </p> <ul>
505<p><b>dt</b> &lt; 0.00001 * <a href="chapter_4.2.html#dt_max">dt_max</a> (with dt_max
506= 20.0)</p> </ul> <p>the simulation will be
507aborted. Such situations usually arise
508in case of any numerical problem / instability which causes a
509non-realistic increase of the wind speed.&nbsp; </p> <p>A
510small time step due to a large mean horizontal windspeed
511speed may be enlarged by using a coordinate transformation (see <a href="#galilei_transformation">galilei_transformation</a>),
512in order to spare CPU time.<br> </p> <p>If the
513leapfrog timestep scheme is used (see <a href="#timestep_scheme">timestep_scheme</a>)
514a temporary time step value dt_new is calculated first, with dt_new = <a href="chapter_4.2.html#fcl_factor">cfl_factor</a>
515* dt_crit where dt_crit is the maximum timestep allowed by the CFL and
516diffusion condition. Next it is examined whether dt_new exceeds or
517falls below the
518value of the previous timestep by at
519least +5 % / -2%. If it is smaller, <span style="font-weight: bold;">dt</span>
520= dt_new is immediately used for the next timestep. If it is larger,
521then <span style="font-weight: bold;">dt </span>=
5221.02 * dt_prev
523(previous timestep) is used as the new timestep, however the time
524step is only increased if the last change of the time step is dated
525back at
526least 30 iterations. If dt_new is located in the interval mentioned
527above, then dt
528does not change at all. By doing so, permanent time step changes as
529well as large
530sudden changes (increases) in the time step are avoided.</p> </td>
531</tr> <tr> <td style="vertical-align: top;">
532<p><a name="dt_pr_1d"></a><b>dt_pr_1d</b></p>
533</td> <td style="vertical-align: top;">R</td>
534<td style="vertical-align: top;"><span style="font-style: italic;">9999999.9</span></td>
535<td style="vertical-align: top;"> <p>Temporal
536interval of vertical profile output of the 1D-model
537(in s).&nbsp; </p> <p>Data are written in ASCII
538format to file <a href="chapter_3.4.html#LIST_PROFIL_1D">LIST_PROFIL_1D</a>.
539This parameter is only in effect if the 1d-model has been switched on
540for the
541initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
542= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
543</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="dt_run_control_1d"></a><b>dt_run_control_1d</b></p>
544</td> <td style="vertical-align: top;">R</td>
545<td style="vertical-align: top;"><span style="font-style: italic;">60.0</span></td> <td style="vertical-align: top;"> <p>Temporal interval of
546runtime control output of the 1d-model
547(in s).&nbsp; </p> <p>Data are written in ASCII
548format to file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.
549This parameter is only in effect if the 1d-model is switched on for the
550initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
551= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
552</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="dx"></a><b>dx</b></p>
553</td> <td style="vertical-align: top;">R</td>
554<td style="vertical-align: top;"><span style="font-style: italic;">1.0</span></td> <td style="vertical-align: top;"> <p>Horizontal grid
555spacing along the x-direction (in m).&nbsp; </p> <p>Along
556x-direction only a constant grid spacing is allowed.</p> </td>
557</tr> <tr> <td style="vertical-align: top;">
558<p><a name="dy"></a><b>dy</b></p>
559</td> <td style="vertical-align: top;">R</td>
560<td style="vertical-align: top;"><span style="font-style: italic;">1.0</span></td> <td style="vertical-align: top;"> <p>Horizontal grid
561spacing along the y-direction (in m).&nbsp; </p> <p>Along y-direction only a constant grid spacing is allowed.</p> </td>
562</tr> <tr> <td style="vertical-align: top;">
563<p><a name="dz"></a><b>dz</b></p>
564</td> <td style="vertical-align: top;">R</td>
565<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Vertical grid
566spacing (in m).&nbsp; </p> <p>This parameter must be
567assigned by the user, because no
568default value is given.<br> </p> <p>By default, the
569model uses constant grid spacing along z-direction, but it can be
570stretched using the parameters <a href="#dz_stretch_level">dz_stretch_level</a>
571and <a href="#dz_stretch_factor">dz_stretch_factor</a>.
572In case of stretching, a maximum allowed grid spacing can be given by <a href="#dz_max">dz_max</a>.<br> </p> <p>Assuming
573a constant <span style="font-weight: bold;">dz</span>,
574the scalar levels (zu) are calculated directly by:&nbsp; </p>
575<ul> <p>zu(0) = - dz * 0.5&nbsp; <br>
576zu(1) = dz * 0.5</p> </ul> <p>The w-levels lie
577half between them:&nbsp; </p> <ul> <p>zw(k) =
578( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
579<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
580spacing (in m).<br><br>If the vertical grid is stretched
581(see <a href="#dz_stretch_factor">dz_stretch_factor</a>
582and <a href="#dz_stretch_level">dz_stretch_level</a>),
583<span style="font-weight: bold;">dz_max</span> can
584be used to limit the vertical grid spacing.</td></tr><tr>
585<td style="vertical-align: top;"> <p><a name="dz_stretch_factor"></a><b>dz_stretch_factor</b></p>
586</td> <td style="vertical-align: top;">R</td>
587<td style="vertical-align: top;"><span style="font-style: italic;">1.08</span></td> <td style="vertical-align: top;"> <p>Stretch factor for a
588vertically stretched grid (see <a href="#dz_stretch_level">dz_stretch_level</a>).&nbsp;
589</p> <p>The stretch factor should not exceed a value of
590approx. 1.10 -
5911.12, otherwise the discretization errors due to the stretched grid not
592negligible any more. (refer Kalnay de Rivas)</p> </td> </tr>
593<tr> <td style="vertical-align: top;"> <p><a name="dz_stretch_level"></a><b>dz_stretch_level</b></p>
594</td> <td style="vertical-align: top;">R</td>
595<td style="vertical-align: top;"><span style="font-style: italic;">100000.0</span><br> </td>
596<td style="vertical-align: top;"> <p>Height level
597above which the grid is to be stretched
598vertically (in m).&nbsp; </p> <p>The vertical grid
599spacings <a href="#dz">dz</a>
600above this level are calculated as&nbsp; </p> <ul> <p><b>dz</b>(k+1)
601= <b>dz</b>(k) * <a href="#dz_stretch_factor">dz_stretch_factor</a></p>
602</ul> <p>and used as spacings for the scalar levels (zu).
603The
604w-levels are then defined as:&nbsp; </p> <ul> <p>zw(k)
605= ( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
606<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="e_min"></a>e_min</span></td>
607<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">0.0</span></td> <td>Minimum
608subgrid-scale TKE in m<sup>2</sup>s<sup>-2</sup>.<br>
609<br>This
610option&nbsp;adds artificial viscosity to the flow by ensuring that
611the
612subgrid-scale TKE does not fall below the minimum threshold <span style="font-weight: bold;">e_min</span>.</td> </tr>
613<tr> <td style="vertical-align: top;"> <p><a name="end_time_1d"></a><b>end_time_1d</b></p>
614</td> <td style="vertical-align: top;">R</td>
615<td style="vertical-align: top;"><span style="font-style: italic;">864000.0</span><br> </td>
616<td style="vertical-align: top;"> <p>Time to be
617simulated for the 1d-model (in s).&nbsp; </p> <p>The
618default value corresponds to a simulated time of 10 days.
619Usually, after such a period the inertia oscillations have completely
620decayed and the solution of the 1d-model can be regarded as stationary
621(see <a href="#damp_level_1d">damp_level_1d</a>).
622This parameter is only in effect if the 1d-model is switched on for the
623initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
624= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
625</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="fft_method"></a><b>fft_method</b></p>
626</td> <td style="vertical-align: top;">C * 20</td>
627<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>
628<td style="vertical-align: top;"> <p>FFT-method to
629be used.<br> </p> <p><br>
630The fast fourier transformation (FFT) is used for solving the
631perturbation pressure equation with a direct method (see <a href="chapter_4.2.html#psolver">psolver</a>)
632and for calculating power spectra (see optional software packages,
633section <a href="chapter_4.2.html#spectra_package">4.2</a>).</p>
634<p><br>
635By default, system-specific, optimized routines from external
636vendor libraries are used. However, these are available only on certain
637computers and there are more or less severe restrictions concerning the
638number of gridpoints to be used with them.<br> </p> <p>There
639are two other PALM internal methods available on every
640machine (their respective source code is part of the PALM source code):</p>
641<p>1.: The <span style="font-weight: bold;">Temperton</span>-method
642from Clive Temperton (ECWMF) which is computationally very fast and
643switched on with <b>fft_method</b> = <span style="font-style: italic;">'temperton-algorithm'</span>.
644The number of horizontal gridpoints (nx+1, ny+1) to be used with this
645method must be composed of prime factors 2, 3 and 5.<br> </p>
6462.: The <span style="font-weight: bold;">Singleton</span>-method
647which is very slow but has no restrictions concerning the number of
648gridpoints to be used with, switched on with <b>fft_method</b>
649= <span style="font-style: italic;">'singleton-algorithm'</span>.
650</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="galilei_transformation"></a><b>galilei_transformation</b></p>
651</td> <td style="vertical-align: top;">L</td>
652<td style="vertical-align: top;"><i>.F.</i></td>
653<td style="vertical-align: top;">Application of a
654Galilei-transformation to the
655coordinate
656system of the model.<br><p>With <b>galilei_transformation</b>
657= <i>.T.,</i> a so-called
658Galilei-transformation is switched on which ensures that the coordinate
659system of the model is moved along with the geostrophical wind.
660Alternatively, the model domain can be moved along with the averaged
661horizontal wind (see <a href="#use_ug_for_galilei_tr">use_ug_for_galilei_tr</a>,
662this can and will naturally change in time). With this method,
663numerical inaccuracies of the Piascek - Williams - scheme (concerns in
664particular the momentum advection) are minimized. Beyond that, in the
665majority of cases the lower relative velocities in the moved system
666permit a larger time step (<a href="#dt">dt</a>).
667Switching the transformation on is only worthwhile if the geostrophical
668wind (ug, vg)
669and the averaged horizontal wind clearly deviate from the value 0. In
670each case, the distance the coordinate system has been moved is written
671to the file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.&nbsp;
672</p> <p>Non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
673and <a href="#bc_ns">bc_ns</a>), the specification
674of a gestrophic
675wind that is not constant with height
676as well as e.g. stationary inhomogeneities at the bottom boundary do
677not allow the use of this transformation.</p> </td> </tr>
678<tr> <td style="vertical-align: top;"> <p><a name="grid_matching"></a><b>grid_matching</b></p>
679</td> <td style="vertical-align: top;">C * 6</td>
680<td style="vertical-align: top;"><span style="font-style: italic;">'match'</span></td> <td style="vertical-align: top;">Variable to adjust the
681subdomain
682sizes in parallel runs.<br> <br>
683For <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>,
684the subdomains are forced to have an identical
685size on all processors. In this case the processor numbers in the
686respective directions of the virtual processor net must fulfill certain
687divisor conditions concerning the grid point numbers in the three
688directions (see <a href="#nx">nx</a>, <a href="#ny">ny</a>
689and <a href="#nz">nz</a>).
690Advantage of this method is that all PEs bear the same computational
691load.<br> <br>
692There is no such restriction by default, because then smaller
693subdomains are allowed on those processors which
694form the right and/or north boundary of the virtual processor grid. On
695all other processors the subdomains are of same size. Whether smaller
696subdomains are actually used, depends on the number of processors and
697the grid point numbers used. Information about the respective settings
698are 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>
699<br>
700When using a multi-grid method for solving the Poisson equation (see <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/doc/app/chapter_4.2.html#psolver">psolver</a>)
701only <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>
702is allowed.<br> <br> <b>Note:</b><br>
703In some cases for small processor numbers there may be a very bad load
704balancing among the
705processors which may reduce the performance of the code.</td> </tr>
706<tr> <td style="vertical-align: top;"><a name="inflow_disturbance_begin"></a><b>inflow_disturbance_<br>
707begin</b></td> <td style="vertical-align: top;">I</td>
708<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>
709<td style="vertical-align: top;">Lower
710limit of the horizontal range for which random perturbations are to be
711imposed on the horizontal velocity field (gridpoints).<br> <br>
712If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
713or <a href="#bc_ns">bc_ns</a>),
714this parameter gives the gridpoint number (counted horizontally from
715the inflow)&nbsp; from which on perturbations are imposed on the
716horizontal velocity field. Perturbations must be switched on with
717parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
718</tr> <tr> <td style="vertical-align: top;"><a name="inflow_disturbance_end"></a><b>inflow_disturbance_<br>
719end</b></td> <td style="vertical-align: top;">I</td>
720<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
721limit of the horizontal range for which random perturbations are
722to be imposed on the horizontal velocity field (gridpoints).<br> <br>
723If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
724or <a href="#bc_ns">bc_ns</a>),
725this parameter gives the gridpoint number (counted horizontally from
726the inflow)&nbsp; unto which perturbations are imposed on the
727horizontal
728velocity field. Perturbations must be switched on with parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
729</tr> <tr> <td style="vertical-align: top;">
730<p><a name="initializing_actions"></a><b>initializing_actions</b></p>
731</td> <td style="vertical-align: top;">C * 100</td>
732<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p style="font-style: normal;">Initialization actions
733to be carried out.&nbsp; </p> <p style="font-style: normal;">This parameter does not have a
734default value and therefore must be assigned with each model run. For
735restart runs <b>initializing_actions</b> = <span style="font-style: italic;">'read_restart_data'</span>
736must be set. For the initial run of a job chain the following values
737are allowed:&nbsp; </p> <p style="font-style: normal;"><span style="font-style: italic;">'set_constant_profiles'</span>
738</p> <ul> <p>A horizontal wind profile consisting
739of linear sections (see <a href="#ug_surface">ug_surface</a>,
740<a href="#ug_vertical_gradient">ug_vertical_gradient</a>,
741<a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
742and <a href="#vg_surface">vg_surface</a>, <a href="#vg_vertical_gradient">vg_vertical_gradient</a>,
743<a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
744respectively) as well as a vertical temperature (humidity) profile
745consisting of
746linear sections (see <a href="#pt_surface">pt_surface</a>,
747<a href="#pt_vertical_gradient">pt_vertical_gradient</a>,
748<a href="#q_surface">q_surface</a>
749and <a href="#q_vertical_gradient">q_vertical_gradient</a>)
750are assumed as initial profiles. The subgrid-scale TKE is set to 0 but K<sub>m</sub>
751and K<sub>h</sub> are set to very small values because
752otherwise no TKE
753would be generated.</p> </ul> <p style="font-style: italic;">'set_1d-model_profiles' </p>
754<ul> <p>The arrays of the 3d-model are initialized with
755the
756(stationary) solution of the 1d-model. These are the variables e, kh,
757km, u, v and with Prandtl layer switched on rif, us, usws, vsws. The
758temperature (humidity) profile consisting of linear sections is set as
759for 'set_constant_profiles' and assumed as constant in time within the
7601d-model. For steering of the 1d-model a set of parameters with suffix
761"_1d" (e.g. <a href="#end_time_1d">end_time_1d</a>,
762<a href="#damp_level_1d">damp_level_1d</a>)
763is available.</p> </ul> <p><span style="font-style: italic;">'by_user'</span></p><p style="margin-left: 40px;">The initialization of the arrays
764of the 3d-model is under complete control of the user and has to be
765done in routine <a href="chapter_3.5.1.html#user_init_3d_model">user_init_3d_model</a>
766of the user-interface.<span style="font-style: italic;"></span></p><p><span style="font-style: italic;">'initialize_vortex'</span>
767</p> <div style="margin-left: 40px;">The initial
768velocity field of the
7693d-model corresponds to a
770Rankine-vortex with vertical axis. This setting may be used to test
771advection 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>)
772are necessary. In order not to distort the vortex, an initial
773horizontal wind profile constant
774with height is necessary (to be set by <b>initializing_actions</b>
775= <span style="font-style: italic;">'set_constant_profiles'</span>)
776and some other conditions have to be met (neutral stratification,
777diffusion must be
778switched off, see <a href="#km_constant">km_constant</a>).
779The center of the vortex is located at jc = (nx+1)/2. It
780extends from k = 0 to k = nz+1. Its radius is 8 * <a href="#dx">dx</a>
781and the exponentially decaying part ranges to 32 * <a href="#dx">dx</a>
782(see init_rankine.f90). </div> <p><span style="font-style: italic;">'initialize_ptanom'</span>
783</p> <ul> <p>A 2d-Gauss-like shape disturbance
784(x,y) is added to the
785initial temperature field with radius 10.0 * <a href="#dx">dx</a>
786and center at jc = (nx+1)/2. This may be used for tests of scalar
787advection schemes
788(see <a href="#scalar_advec">scalar_advec</a>).
789Such tests require a horizontal wind profile constant with hight and
790diffusion
791switched off (see <span style="font-style: italic;">'initialize_vortex'</span>).
792Additionally, the buoyancy term
793must be switched of in the equation of motion&nbsp; for w (this
794requires the user to comment out the call of <span style="font-family: monospace;">buoyancy</span> in the
795source code of <span style="font-family: monospace;">prognostic_equations.f90</span>).</p>
796</ul> <p style="font-style: normal;">Values may be
797combined, e.g. <b>initializing_actions</b> = <span style="font-style: italic;">'set_constant_profiles
798initialize_vortex'</span>, but the values of <span style="font-style: italic;">'set_constant_profiles'</span>,
799<span style="font-style: italic;">'set_1d-model_profiles'</span>
800, and <span style="font-style: italic;">'by_user'</span>
801must not be given at the same time.</p> <p style="font-style: italic;"> </p> </td> </tr>
802<tr> <td style="vertical-align: top;"> <p><a name="km_constant"></a><b>km_constant</b></p>
803</td> <td style="vertical-align: top;">R</td>
804<td style="vertical-align: top;"><i>variable<br>
805(computed from TKE)</i></td> <td style="vertical-align: top;"> <p>Constant eddy
806diffusivities are used (laminar
807simulations).&nbsp; </p> <p>If this parameter is
808specified, both in the 1d and in the
8093d-model constant values for the eddy diffusivities are used in
810space and time with K<sub>m</sub> = <b>km_constant</b>
811and K<sub>h</sub> = K<sub>m</sub> / <a href="chapter_4.2.html#prandtl_number">prandtl_number</a>.
812The prognostic equation for the subgrid-scale TKE is switched off.
813Constant eddy diffusivities are only allowed with the Prandtl layer (<a href="#prandtl_layer">prandtl_layer</a>)
814switched off.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="km_damp_max"></a><b>km_damp_max</b></p>
815</td> <td style="vertical-align: top;">R</td>
816<td style="vertical-align: top;"><span style="font-style: italic;">0.5*(dx
817or dy)</span></td> <td style="vertical-align: top;">Maximum
818diffusivity used for filtering the velocity field in the vicinity of
819the outflow (in m<sup>2</sup>/s).<br> <br>
820When using non-cyclic lateral boundaries (see <a href="#bc_lr">bc_lr</a>
821or <a href="#bc_ns">bc_ns</a>),
822a smoothing has to be applied to the
823velocity field in the vicinity of the outflow in order to suppress any
824reflections of outgoing disturbances. Smoothing is done by increasing
825the eddy diffusivity along the horizontal direction which is
826perpendicular to the outflow boundary. Only velocity components
827parallel to the outflow boundary are filtered (e.g. v and w, if the
828outflow is along x). Damping is applied from the bottom to the top of
829the domain.<br> <br>
830The horizontal range of the smoothing is controlled by <a href="#outflow_damping_width">outflow_damping_width</a>
831which defines the number of gridpoints (counted from the outflow
832boundary) from where on the smoothing is applied. Starting from that
833point, the eddy diffusivity is linearly increased (from zero to its
834maximum value given by <span style="font-weight: bold;">km_damp_max</span>)
835until half of the damping range width, from where it remains constant
836up to the outflow boundary. If at a certain grid point the eddy
837diffusivity calculated from the flow field is larger than as described
838above, it is used instead.<br> <br>
839The default value of <span style="font-weight: bold;">km_damp_max</span>
840has been empirically proven to be sufficient.</td> </tr> <tr>
841<td style="vertical-align: top;"> <p><a name="long_filter_factor"></a><b>long_filter_factor</b></p>
842</td> <td style="vertical-align: top;">R</td>
843<td style="vertical-align: top;"><i>0.0</i></td>
844<td style="vertical-align: top;"> <p>Filter factor
845for the so-called Long-filter.<br> </p> <p><br>
846This filter very efficiently
847eliminates 2-delta-waves sometimes cauesed by the upstream-spline
848scheme (see Mahrer and
849Pielke, 1978: Mon. Wea. Rev., 106, 818-830). It works in all three
850directions in space. A value of <b>long_filter_factor</b>
851= <i>0.01</i>
852sufficiently removes the small-scale waves without affecting the
853longer waves.<br> </p> <p>By default, the filter is
854switched off (= <i>0.0</i>).
855It is exclusively applied to the tendencies calculated by the
856upstream-spline scheme (see <a href="#momentum_advec">momentum_advec</a>
857and <a href="#scalar_advec">scalar_advec</a>),
858not to the prognostic variables themselves. At the bottom and top
859boundary of the model domain the filter effect for vertical
8602-delta-waves is reduced. There, the amplitude of these waves is only
861reduced by approx. 50%, otherwise by nearly 100%.&nbsp; <br>
862Filter factors with values &gt; <i>0.01</i> also
863reduce the amplitudes
864of waves with wavelengths longer than 2-delta (see the paper by Mahrer
865and
866Pielke, 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
867default, the optimization method depends on the host on which PALM is
868running. On machines with vector-type CPUs, single 3d-loops are used to
869calculate each tendency term of each prognostic equation, while on all
870other machines, all prognostic equations are solved within one big loop
871over 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>
872<td style="vertical-align: top;"><a name="mixing_length_1d"></a><span style="font-weight: bold;">mixing_length_1d</span><br>
873</td> <td style="vertical-align: top;">C*20<br>
874</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>
875<td style="vertical-align: top;">Mixing length used in the
8761d-model.<br> <br>
877By default the mixing length is calculated as in the 3d-model (i.e. it
878depends on the grid spacing).<br> <br>
879By setting <span style="font-weight: bold;">mixing_length_1d</span>
880= <span style="font-style: italic;">'blackadar'</span>,
881the so-called Blackadar mixing length is used (l = kappa * z / ( 1 +
882kappa * z / lambda ) with the limiting value lambda = 2.7E-4 * u_g / f).<br>
883</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="humidity"></a><b>humidity</b></p>
884</td> <td style="vertical-align: top;">L</td>
885<td style="vertical-align: top;"><i>.F.</i></td>
886<td style="vertical-align: top;"> <p>Parameter to
887switch on the prognostic equation for specific
888humidity q.<br> </p> <p>The initial vertical
889profile 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>
890and <a href="chapter_4.1.html#q_vertical_gradient_level">q_vertical_gradient_level</a>.&nbsp;
891Boundary conditions can be set via <a href="chapter_4.1.html#q_surface_initial_change">q_surface_initial_change</a>
892and <a href="chapter_4.1.html#surface_waterflux">surface_waterflux</a>.<br>
893</p>
894If the condensation scheme is switched on (<a href="chapter_4.1.html#cloud_physics">cloud_physics</a>
895= .TRUE.), q becomes the total liquid water content (sum of specific
896humidity and liquid water content).</td> </tr>
897<tr> <td style="vertical-align: top;"> <p><a name="momentum_advec"></a><b>momentum_advec</b></p>
898</td> <td style="vertical-align: top;">C * 10</td>
899<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
900<td style="vertical-align: top;"> <p>Advection
901scheme to be used for the momentum equations.<br> <br>
902The user can choose between the following schemes:<br>
903&nbsp;<br> <br> <span style="font-style: italic;">'pw-scheme'</span><br>
904</p> <div style="margin-left: 40px;">The scheme of
905Piascek and
906Williams (1970, J. Comp. Phys., 6,
907392-405) with central differences in the form C3 is used.<br>
908If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
909= <span style="font-style: italic;">'leapfrog+euler'</span>
910the
911advection scheme is - for the Euler-timestep - automatically switched
912to an upstream-scheme.<br> </div> <p> </p> <p><span style="font-style: italic;">'ups-scheme'</span><br>
913</p> <div style="margin-left: 40px;">The
914upstream-spline scheme is
915used
916(see Mahrer and Pielke,
9171978: Mon. Wea. Rev., 106, 818-830). In opposite to the
918Piascek-Williams scheme, this is characterized by much better numerical
919features (less numerical diffusion, better preservation of flow
920structures, e.g. vortices), but computationally it is much more
921expensive. In
922addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
923= <span style="font-style: italic;">'</span><i>euler'</i>),
924i.e. the
925timestep accuracy is only of first order.
926For this reason the advection of scalar variables (see <a href="#scalar_advec">scalar_advec</a>)
927should then also be carried out with the upstream-spline scheme,
928because otherwise the scalar variables would
929be subject to large numerical diffusion due to the upstream
930scheme.&nbsp; </div> <p style="margin-left: 40px;">Since
931the cubic splines used tend
932to overshoot under
933certain circumstances, this effect must be adjusted by suitable
934filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
935<a href="#long_filter_factor">long_filter_factor</a>,
936<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>).
937This is always neccessary for runs with stable stratification,
938even if this stratification appears only in parts of the model domain.<br>
939</p> <div style="margin-left: 40px;">With stable
940stratification the
941upstream-spline scheme also
942produces gravity waves with large amplitude, which must be
943suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
944<br> <span style="font-weight: bold;">Important: </span>The&nbsp;
945upstream-spline scheme is not implemented for humidity and passive
946scalars (see&nbsp;<a href="#humidity">humidity</a>
947and <a href="#passive_scalar">passive_scalar</a>)
948and requires the use of a 2d-domain-decomposition. The last conditions
949severely restricts code optimization on several machines leading to
950very long execution times! The scheme is also not allowed for
951non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
952and <a href="#bc_ns">bc_ns</a>).</div> </td>
953</tr> <tr> <td style="vertical-align: top;"><a name="netcdf_precision"></a><span style="font-weight: bold;">netcdf_precision</span><br>
954</td> <td style="vertical-align: top;">C*20<br>
955(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>
956<td style="vertical-align: top;">Defines the accuracy of
957the NetCDF output.<br> <br>
958By default, all NetCDF output data (see <a href="chapter_4.2.html#data_output_format">data_output_format</a>)
959have single precision&nbsp; (4 byte) accuracy. Double precision (8
960byte) can be choosen alternatively.<br>
961Accuracy for the different output data (cross sections, 3d-volume data,
962spectra, etc.) can be set independently.<br> <span style="font-style: italic;">'&lt;out&gt;_NF90_REAL4'</span>
963(single precision) or <span style="font-style: italic;">'&lt;out&gt;_NF90_REAL8'</span>
964(double precision) are the two principally allowed values for <span style="font-weight: bold;">netcdf_precision</span>,
965where the string <span style="font-style: italic;">'&lt;out&gt;'
966</span>can be chosen out of the following list:<br> <br>
967<table style="text-align: left; width: 284px; height: 234px;" border="1" cellpadding="2" cellspacing="2"> <tbody>
968<tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xy'</span><br> </td>
969<td style="vertical-align: top;">horizontal cross section<br>
970</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xz'</span><br> </td>
971<td style="vertical-align: top;">vertical (xz) cross
972section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'yz'</span><br> </td>
973<td style="vertical-align: top;">vertical (yz) cross
974section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'2d'</span><br> </td>
975<td style="vertical-align: top;">all cross sections<br>
976</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'3d'</span><br> </td>
977<td style="vertical-align: top;">volume data<br> </td>
978</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'pr'</span><br> </td>
979<td style="vertical-align: top;">vertical profiles<br>
980</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'ts'</span><br> </td>
981<td style="vertical-align: top;">time series, particle
982time series<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'sp'</span><br> </td>
983<td style="vertical-align: top;">spectra<br> </td>
984</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'prt'</span><br> </td>
985<td style="vertical-align: top;">particles<br> </td>
986</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'all'</span><br> </td>
987<td style="vertical-align: top;">all output quantities<br>
988</td> </tr> </tbody> </table> <br> <span style="font-weight: bold;">Example:</span><br>
989If all cross section data and the particle data shall be output in
990double 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>
991has to be assigned.<br> </td> </tr>
992<tr> <td style="vertical-align: top;"> <p><a name="npex"></a><b>npex</b></p> </td>
993<td style="vertical-align: top;">I</td> <td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
994along x-direction of the virtual
995processor
996net.&nbsp; </p> <p>For parallel runs, the total
997number of processors to be used
998is given by
999the <span style="font-weight: bold;">mrun</span>
1000option <a href="http://www.muk.uni-hannover.de/software/mrun_beschreibung.html#Opt-X">-X</a>.
1001By default, depending on the type of the parallel computer, PALM
1002generates a 1d processor
1003net (domain decomposition along x, <span style="font-weight: bold;">npey</span>
1004= <span style="font-style: italic;">1</span>) or a
10052d-net (this is
1006favored on machines with fast communication network). In case of a
10072d-net, it is tried to make it more or less square-shaped. If, for
1008example, 16 processors are assigned (-X 16), a 4 * 4 processor net is
1009generated (<span style="font-weight: bold;">npex</span>
1010= <span style="font-style: italic;">4</span>, <span style="font-weight: bold;">npey</span>
1011= <span style="font-style: italic;">4</span>).
1012This choice is optimal for square total domains (<a href="#nx">nx</a>
1013= <a href="#ny">ny</a>),
1014since then the number of ghost points at the lateral boundarys of
1015the subdomains is minimal. If <span style="font-weight: bold;">nx</span>
1016nd <span style="font-weight: bold;">ny</span>
1017differ extremely, the
1018processor 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>
1019<p><b>Important:</b> The value of <span style="font-weight: bold;">npex</span> * <span style="font-weight: bold;">npey</span> must exactly
1020correspond to the
1021value assigned by the <span style="font-weight: bold;">mrun</span>-option
1022<tt>-X</tt>.
1023Otherwise the model run will abort with a corresponding error
1024message.&nbsp; <br>
1025Additionally, the specification of <span style="font-weight: bold;">npex</span>
1026and <span style="font-weight: bold;">npey</span>
1027may of course
1028override the default setting for the domain decomposition (1d or 2d)
1029which may have a significant (negative) effect on the code performance.
1030</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="npey"></a><b>npey</b></p>
1031</td> <td style="vertical-align: top;">I</td>
1032<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
1033along y-direction of the virtual
1034processor
1035net.&nbsp; </p> <p>For further information see <a href="#npex">npex</a>.</p> </td> </tr>
1036<tr> <td style="vertical-align: top;"> <p><a name="nsor_ini"></a><b>nsor_ini</b></p>
1037</td> <td style="vertical-align: top;">I</td>
1038<td style="vertical-align: top;"><i>100</i></td>
1039<td style="vertical-align: top;"> <p>Initial number
1040of iterations with the SOR algorithm.&nbsp; </p> <p>This
1041parameter is only effective if the SOR algorithm was
1042selected as the pressure solver scheme (<a href="chapter_4.2.html#psolver">psolver</a>
1043= <span style="font-style: italic;">'sor'</span>)
1044and specifies the
1045number of initial iterations of the SOR
1046scheme (at t = 0). The number of subsequent iterations at the following
1047timesteps is determined
1048with the parameter <a href="#nsor">nsor</a>.
1049Usually <b>nsor</b> &lt; <b>nsor_ini</b>,
1050since in each case
1051subsequent calls to <a href="chapter_4.2.html#psolver">psolver</a>
1052use the solution of the previous call as initial value. Suitable
1053test runs should determine whether sufficient convergence of the
1054solution is obtained with the default value and if necessary the value
1055of <b>nsor_ini</b> should be changed.</p> </td>
1056</tr> <tr> <td style="vertical-align: top;">
1057<p><a name="nx"></a><b>nx</b></p>
1058</td> <td style="vertical-align: top;">I</td>
1059<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1060points in x-direction.&nbsp; </p> <p>A value for this
1061parameter must be assigned. Since the lower
1062array bound in PALM
1063starts with i = 0, the actual number of grid points is equal to <b>nx+1</b>.
1064In case of cyclic boundary conditions along x, the domain size is (<b>nx+1</b>)*
1065<a href="#dx">dx</a>.</p> <p>For
1066parallel runs, in case of <a href="#grid_matching">grid_matching</a>
1067= <span style="font-style: italic;">'strict'</span>,
1068<b>nx+1</b> must
1069be an integral multiple
1070of the processor numbers (see <a href="#npex">npex</a>
1071and <a href="#npey">npey</a>)
1072along x- as well as along y-direction (due to data
1073transposition restrictions).</p> </td> </tr> <tr>
1074<td style="vertical-align: top;"> <p><a name="ny"></a><b>ny</b></p>
1075</td> <td style="vertical-align: top;">I</td>
1076<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1077points in y-direction.&nbsp; </p> <p>A value for this
1078parameter must be assigned. Since the lower
1079array bound in PALM starts with i = 0, the actual number of grid points
1080is equal to <b>ny+1</b>. In case of cyclic boundary
1081conditions along
1082y, the domain size is (<b>ny+1</b>) * <a href="#dy">dy</a>.</p>
1083<p>For parallel runs, in case of <a href="#grid_matching">grid_matching</a>
1084= <span style="font-style: italic;">'strict'</span>,
1085<b>ny+1</b> must
1086be an integral multiple
1087of the processor numbers (see <a href="#npex">npex</a>
1088and <a href="#npey">npey</a>)&nbsp;
1089along y- as well as along x-direction (due to data
1090transposition restrictions).</p> </td> </tr> <tr>
1091<td style="vertical-align: top;"> <p><a name="nz"></a><b>nz</b></p>
1092</td> <td style="vertical-align: top;">I</td>
1093<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1094points in z-direction.&nbsp; </p> <p>A value for this
1095parameter must be assigned. Since the lower
1096array bound in PALM
1097starts with k = 0 and since one additional grid point is added at the
1098top boundary (k = <b>nz+1</b>), the actual number of grid
1099points is <b>nz+2</b>.
1100However, the prognostic equations are only solved up to <b>nz</b>
1101(u,
1102v)
1103or up to <b>nz-1</b> (w, scalar quantities). The top
1104boundary for u
1105and v is at k = <b>nz+1</b> (u, v) while at k = <b>nz</b>
1106for all
1107other quantities.&nbsp; </p> <p>For parallel
1108runs,&nbsp; in case of <a href="#grid_matching">grid_matching</a>
1109= <span style="font-style: italic;">'strict'</span>,
1110<b>nz</b> must
1111be an integral multiple of
1112the number of processors in x-direction (due to data transposition
1113restrictions).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="omega"></a><b>omega</b></p>
1114</td> <td style="vertical-align: top;">R</td>
1115<td style="vertical-align: top;"><i>7.29212E-5</i></td>
1116<td style="vertical-align: top;"> <p>Angular
1117velocity of the rotating system (in rad s<sup>-1</sup>).&nbsp;
1118</p> <p>The angular velocity of the earth is set by
1119default. The
1120values
1121of the Coriolis parameters are calculated as:&nbsp; </p> <ul>
1122<p>f = 2.0 * <b>omega</b> * sin(<a href="#phi">phi</a>)&nbsp;
1123<br>f* = 2.0 * <b>omega</b> * cos(<a href="#phi">phi</a>)</p>
1124</ul> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="outflow_damping_width"></a><b>outflow_damping_width</b></p>
1125</td> <td style="vertical-align: top;">I</td>
1126<td style="vertical-align: top;"><span style="font-style: italic;">MIN(20,
1127nx/2</span> or <span style="font-style: italic;">ny/2)</span></td>
1128<td style="vertical-align: top;">Width of
1129the damping range in the vicinity of the outflow (gridpoints).<br>
1130<br>
1131When using non-cyclic lateral boundaries (see <a href="chapter_4.1.html#bc_lr">bc_lr</a>
1132or <a href="chapter_4.1.html#bc_ns">bc_ns</a>),
1133a smoothing has to be applied to the
1134velocity field in the vicinity of the outflow in order to suppress any
1135reflections of outgoing disturbances. This parameter controlls the
1136horizontal range to which the smoothing is applied. The range is given
1137in gridpoints counted from the respective outflow boundary. For further
1138details about the smoothing see parameter <a href="chapter_4.1.html#km_damp_max">km_damp_max</a>,
1139which defines the magnitude of the damping.</td> </tr>
1140<tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_e"></a><b>overshoot_limit_e</b></p>
1141</td> <td style="vertical-align: top;">R</td>
1142<td style="vertical-align: top;"><i>0.0</i></td>
1143<td style="vertical-align: top;"> <p>Allowed limit
1144for the overshooting of subgrid-scale TKE in
1145case that the upstream-spline scheme is switched on (in m<sup>2</sup>/s<sup>2</sup>).&nbsp;
1146</p> <p>By deafult, if cut-off of overshoots is switched
1147on for the
1148upstream-spline scheme (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>),
1149no overshoots are permitted at all. If <b>overshoot_limit_e</b>
1150is given a non-zero value, overshoots with the respective
1151amplitude (both upward and downward) are allowed.&nbsp; </p>
1152<p>Only positive values are allowed for <b>overshoot_limit_e</b>.</p>
1153</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_pt"></a><b>overshoot_limit_pt</b></p>
1154</td> <td style="vertical-align: top;">R</td>
1155<td style="vertical-align: top;"><i>0.0</i></td>
1156<td style="vertical-align: top;"> <p>Allowed limit
1157for the overshooting of potential temperature in
1158case that the upstream-spline scheme is switched on (in K).&nbsp; </p>
1159<p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1160</p> <p>Only positive values are allowed for <b>overshoot_limit_pt</b>.</p>
1161</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_u"></a><b>overshoot_limit_u</b></p>
1162</td> <td style="vertical-align: top;">R</td>
1163<td style="vertical-align: top;"><i>0.0</i></td>
1164<td style="vertical-align: top;">Allowed limit for the
1165overshooting of
1166the u-component of velocity in case that the upstream-spline scheme is
1167switched on (in m/s). <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1168</p> <p>Only positive values are allowed for <b>overshoot_limit_u</b>.</p>
1169</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_v"></a><b>overshoot_limit_v</b></p>
1170</td> <td style="vertical-align: top;">R</td>
1171<td style="vertical-align: top;"><i>0.0</i></td>
1172<td style="vertical-align: top;"> <p>Allowed limit
1173for the overshooting of the v-component of
1174velocity in case that the upstream-spline scheme is switched on
1175(in m/s).&nbsp; </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1176</p> <p>Only positive values are allowed for <b>overshoot_limit_v</b>.</p>
1177</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_w"></a><b>overshoot_limit_w</b></p>
1178</td> <td style="vertical-align: top;">R</td>
1179<td style="vertical-align: top;"><i>0.0</i></td>
1180<td style="vertical-align: top;"> <p>Allowed limit
1181for the overshooting of the w-component of
1182velocity in case that the upstream-spline scheme is switched on
1183(in m/s).&nbsp; </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1184</p> <p>Only positive values are permitted for <b>overshoot_limit_w</b>.</p>
1185</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="passive_scalar"></a><b>passive_scalar</b></p>
1186</td> <td style="vertical-align: top;">L</td>
1187<td style="vertical-align: top;"><i>.F.</i></td>
1188<td style="vertical-align: top;"> <p>Parameter to
1189switch on the prognostic equation for a passive
1190scalar. <br> </p> <p>The initial vertical profile
1191of s can be set via parameters <a href="#s_surface">s_surface</a>,
1192<a href="#s_vertical_gradient">s_vertical_gradient</a>
1193and&nbsp; <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
1194Boundary conditions can be set via <a href="#s_surface_initial_change">s_surface_initial_change</a>
1195and <a href="#surface_scalarflux">surface_scalarflux</a>.&nbsp;
1196</p> <p><b>Note:</b> <br>
1197With <span style="font-weight: bold;">passive_scalar</span>
1198switched
1199on, the simultaneous use of humidity (see&nbsp;<a href="#humidity">humidity</a>)
1200is impossible.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="phi"></a><b>phi</b></p>
1201</td> <td style="vertical-align: top;">R</td>
1202<td style="vertical-align: top;"><i>55.0</i></td>
1203<td style="vertical-align: top;"> <p>Geographical
1204latitude (in degrees).&nbsp; </p> <p>The value of
1205this parameter determines the value of the
1206Coriolis parameters f and f*, provided that the angular velocity (see <a href="#omega">omega</a>)
1207is non-zero.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="prandtl_layer"></a><b>prandtl_layer</b></p>
1208</td> <td style="vertical-align: top;">L</td>
1209<td style="vertical-align: top;"><i>.T.</i></td>
1210<td style="vertical-align: top;"> <p>Parameter to
1211switch on a Prandtl layer.&nbsp; </p> <p>By default,
1212a Prandtl layer is switched on at the bottom
1213boundary between z = 0 and z = 0.5 * <a href="#dz">dz</a>
1214(the first computational grid point above ground for u, v and the
1215scalar quantities).
1216In this case, at the bottom boundary, free-slip conditions for u and v
1217(see <a href="#bc_uv_b">bc_uv_b</a>)
1218are not allowed. Likewise, laminar
1219simulations with constant eddy diffusivities (<a href="#km_constant">km_constant</a>)
1220are forbidden.&nbsp; </p> <p>With Prandtl-layer
1221switched off, the TKE boundary condition <a href="#bc_e_b">bc_e_b</a>
1222= '<i>(u*)**2+neumann'</i> must not be used and is
1223automatically
1224changed to <i>'neumann'</i> if necessary.&nbsp; Also,
1225the pressure
1226boundary condition <a href="#bc_p_b">bc_p_b</a>
1227= <i>'neumann+inhomo'</i>&nbsp; is not allowed. </p>
1228<p>The roughness length is declared via the parameter <a href="#roughness_length">roughness_length</a>.</p>
1229</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="precipitation"></a><b>precipitation</b></p>
1230</td> <td style="vertical-align: top;">L</td>
1231<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p>Parameter to switch
1232on the precipitation scheme.<br> </p> <p>For
1233precipitation processes PALM uses a simplified Kessler
1234scheme. This scheme only considers the
1235so-called autoconversion, that means the generation of rain water by
1236coagulation of cloud drops among themselves. Precipitation begins and
1237is immediately removed from the flow as soon as the liquid water
1238content 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>
1239<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
1240refrence</span></td><td style="vertical-align: top;">Reference
1241temperature to be used in all buoyancy terms (in K).<br><br>By
1242default, the instantaneous horizontal average over the total model
1243domain is used.</td></tr><tr> <td style="vertical-align: top;"> <p><a name="pt_surface"></a><b>pt_surface</b></p>
1244</td> <td style="vertical-align: top;">R</td>
1245<td style="vertical-align: top;"><i>300.0</i></td>
1246<td style="vertical-align: top;"> <p>Surface
1247potential temperature (in K).&nbsp; </p> <p>This
1248parameter assigns the value of the potential temperature
1249pt at the surface (k=0)<b>.</b> Starting from this value,
1250the
1251initial vertical temperature profile is constructed with <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1252and <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level
1253</a>.
1254This profile is also used for the 1d-model as a stationary profile.</p>
1255</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_surface_initial_change"></a><b>pt_surface_initial</b>
1256<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>
1257<td style="vertical-align: top;"> <p>Change in
1258surface temperature to be made at the beginning of
1259the 3d run
1260(in K).&nbsp; </p> <p>If <b>pt_surface_initial_change</b>
1261is set to a non-zero
1262value, the near surface sensible heat flux is not allowed to be given
1263simultaneously (see <a href="#surface_heatflux">surface_heatflux</a>).</p>
1264</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient"></a><b>pt_vertical_gradient</b></p>
1265</td> <td style="vertical-align: top;">R (10)</td>
1266<td style="vertical-align: top;"><i>10 * 0.0</i></td>
1267<td style="vertical-align: top;"> <p>Temperature
1268gradient(s) of the initial temperature profile (in
1269K
1270/ 100 m).&nbsp; </p> <p>This temperature gradient
1271holds starting from the height&nbsp;
1272level defined by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>
1273(precisely: for all uv levels k where zu(k) &gt;
1274pt_vertical_gradient_level,
1275pt_init(k) is set: pt_init(k) = pt_init(k-1) + dzu(k) * <b>pt_vertical_gradient</b>)
1276up to the top boundary or up to the next height level defined
1277by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>.
1278A total of 10 different gradients for 11 height intervals (10 intervals
1279if <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>(1)
1280= <i>0.0</i>) can be assigned. The surface temperature is
1281assigned via <a href="#pt_surface">pt_surface</a>.&nbsp;
1282</p> <p>Example:&nbsp; </p> <ul> <p><b>pt_vertical_gradient</b>
1283= <i>1.0</i>, <i>0.5</i>,&nbsp; <br>
1284<b>pt_vertical_gradient_level</b> = <i>500.0</i>,
1285<i>1000.0</i>,</p> </ul> <p>That
1286defines the temperature profile to be neutrally
1287stratified
1288up to z = 500.0 m with a temperature given by <a href="#pt_surface">pt_surface</a>.
1289For 500.0 m &lt; z &lt;= 1000.0 m the temperature gradient is
12901.0 K /
1291100 m and for z &gt; 1000.0 m up to the top boundary it is
12920.5 K / 100 m (it is assumed that the assigned height levels correspond
1293with uv levels). </p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient_level"></a><b>pt_vertical_gradient</b>
1294<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>&nbsp;
1295<span style="font-style: italic;">0.0</span><br>
1296</p> </td> <td style="vertical-align: top;">
1297<p>Height level from which on the temperature gradient defined by
1298<a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1299is effective (in m).&nbsp; </p> <p>The height levels
1300are to be assigned in ascending order. The
1301default values result in a neutral stratification regardless of the
1302values of <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1303(unless the top boundary of the model is higher than 100000.0 m).
1304For the piecewise construction of temperature profiles see <a href="#pt_vertical_gradient">pt_vertical_gradient</a>.</p>
1305</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface"></a><b>q_surface</b></p>
1306</td> <td style="vertical-align: top;">R</td>
1307<td style="vertical-align: top;"><i>0.0</i></td>
1308<td style="vertical-align: top;"> <p>Surface
1309specific humidity / total water content (kg/kg).&nbsp; </p> <p>This
1310parameter assigns the value of the specific humidity q at
1311the surface (k=0).&nbsp; Starting from this value, the initial
1312humidity
1313profile is constructed with&nbsp; <a href="#q_vertical_gradient">q_vertical_gradient</a>
1314and <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
1315This profile is also used for the 1d-model as a stationary profile.</p>
1316</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface_initial_change"></a><b>q_surface_initial</b>
1317<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R<br> </td> <td style="vertical-align: top;"><i>0.0</i></td>
1318<td style="vertical-align: top;"> <p>Change in
1319surface specific humidity / total water content to
1320be made at the beginning
1321of the 3d run (kg/kg).&nbsp; </p> <p>If <b>q_surface_initial_change</b><i>
1322</i>is set to a
1323non-zero value the
1324near surface latent heat flux (water flux) is not allowed to be given
1325simultaneously (see <a href="#surface_waterflux">surface_waterflux</a>).</p>
1326</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient"></a><b>q_vertical_gradient</b></p>
1327</td> <td style="vertical-align: top;">R (10)</td>
1328<td style="vertical-align: top;"><i>10 * 0.0</i></td>
1329<td style="vertical-align: top;"> <p>Humidity
1330gradient(s) of the initial humidity profile
1331(in 1/100 m).&nbsp; </p> <p>This humidity gradient
1332holds starting from the height
1333level&nbsp; defined by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>
1334(precisely: for all uv levels k, where zu(k) &gt;
1335q_vertical_gradient_level,
1336q_init(k) is set: q_init(k) = q_init(k-1) + dzu(k) * <b>q_vertical_gradient</b>)
1337up to the top boundary or up to the next height level defined
1338by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
1339A total of 10 different gradients for 11 height intervals (10 intervals
1340if <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>(1)
1341= <i>0.0</i>) can be asigned. The surface humidity is
1342assigned
1343via <a href="#q_surface">q_surface</a>. </p>
1344<p>Example:&nbsp; </p> <ul> <p><b>q_vertical_gradient</b>
1345= <i>0.001</i>, <i>0.0005</i>,&nbsp; <br>
1346<b>q_vertical_gradient_level</b> = <i>500.0</i>,
1347<i>1000.0</i>,</p> </ul>
1348That defines the humidity to be constant with height up to z =
1349500.0
1350m with a
1351value given by <a href="#q_surface">q_surface</a>.
1352For 500.0 m &lt; z &lt;= 1000.0 m the humidity gradient is
13530.001 / 100
1354m and for z &gt; 1000.0 m up to the top boundary it is
13550.0005 / 100 m (it is assumed that the assigned height levels
1356correspond with uv
1357levels). </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient_level"></a><b>q_vertical_gradient</b>
1358<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>&nbsp;
1359<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
1360which on the humidity gradient defined by <a href="#q_vertical_gradient">q_vertical_gradient</a>
1361is effective (in m).&nbsp; </p> <p>The height levels
1362are to be assigned in ascending order. The
1363default values result in a humidity constant with height regardless of
1364the values of <a href="#q_vertical_gradient">q_vertical_gradient</a>
1365(unless the top boundary of the model is higher than 100000.0 m). For
1366the piecewise construction of humidity profiles see <a href="#q_vertical_gradient">q_vertical_gradient</a>.</p>
1367</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="radiation"></a><b>radiation</b></p>
1368</td> <td style="vertical-align: top;">L</td>
1369<td style="vertical-align: top;"><i>.F.</i></td>
1370<td style="vertical-align: top;"> <p>Parameter to
1371switch on longwave radiation cooling at
1372cloud-tops.&nbsp; </p> <p>Long-wave radiation
1373processes are parameterized by the
1374effective emissivity, which considers only the absorption and emission
1375of long-wave radiation at cloud droplets. The radiation scheme can be
1376used only with <a href="#cloud_physics">cloud_physics</a>
1377= .TRUE. .</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="random_generator"></a><b>random_generator</b></p>
1378</td> <td style="vertical-align: top;">C * 20</td>
1379<td style="vertical-align: top;"> <p><i>'numerical</i><br>
1380<i>recipes'</i></p> </td> <td style="vertical-align: top;"> <p>Random number
1381generator to be used for creating uniformly
1382distributed random numbers. <br> </p> <p>It is
1383used if random perturbations are to be imposed on the
1384velocity field or on the surface heat flux field (see <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>
1385and <a href="chapter_4.2.html#random_heatflux">random_heatflux</a>).
1386By default, the "Numerical Recipes" random number generator is used.
1387This one provides exactly the same order of random numbers on all
1388different machines and should be used in particular for comparison runs.<br>
1389<br>
1390Besides, a system-specific generator is available ( <b>random_generator</b>
1391= <i>'system-specific')</i> which should particularly be
1392used for runs
1393on vector parallel computers (NEC), because the default generator
1394cannot be vectorized and therefore significantly drops down the code
1395performance on these machines.<br> </p> <span style="font-weight: bold;">Note:</span><br>
1396Results from two otherwise identical model runs will not be comparable
1397one-to-one if they used different random number generators.</td> </tr>
1398<tr> <td style="vertical-align: top;"> <p><a name="random_heatflux"></a><b>random_heatflux</b></p>
1399</td> <td style="vertical-align: top;">L</td>
1400<td style="vertical-align: top;"><i>.F.</i></td>
1401<td style="vertical-align: top;"> <p>Parameter to
1402impose random perturbations on the internal two-dimensional near
1403surface heat flux field <span style="font-style: italic;">shf</span>.
1404<br> </p>If a near surface heat flux is used as bottom
1405boundary
1406condition (see <a href="#surface_heatflux">surface_heatflux</a>),
1407it is by default assumed to be horizontally homogeneous. Random
1408perturbations can be imposed on the internal
1409two-dimensional&nbsp;heat flux field <span style="font-style: italic;">shf</span> by assigning <b>random_heatflux</b>
1410= <i>.T.</i>. The disturbed heat flux field is calculated
1411by
1412multiplying the
1413values at each mesh point with a normally distributed random number
1414with a mean value and standard deviation of 1. This is repeated after
1415every timestep.<br> <br>
1416In case of a non-flat <a href="#topography">topography</a>,&nbsp;assigning
1417<b>random_heatflux</b>
1418= <i>.T.</i> imposes random perturbations on the
1419combined&nbsp;heat
1420flux field <span style="font-style: italic;">shf</span>
1421composed of <a href="#surface_heatflux">surface_heatflux</a>
1422at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
1423at the topography top face.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_max"></a><b>rif_max</b></p>
1424</td> <td style="vertical-align: top;">R</td>
1425<td style="vertical-align: top;"><i>1.0</i></td>
1426<td style="vertical-align: top;"> <p>Upper limit of
1427the flux-Richardson number.&nbsp; </p> <p>With the
1428Prandtl layer switched on (see <a href="#prandtl_layer">prandtl_layer</a>),
1429flux-Richardson numbers (rif) are calculated for z=z<sub>p</sub>
1430(k=1)
1431in the 3d-model (in the 1d model for all heights). Their values in
1432particular determine the
1433values of the friction velocity (1d- and 3d-model) and the values of
1434the eddy diffusivity (1d-model). With small wind velocities at the
1435Prandtl layer top or small vertical wind shears in the 1d-model, rif
1436can take up unrealistic large values. They are limited by an upper (<span style="font-weight: bold;">rif_max</span>) and lower
1437limit (see <a href="#rif_min">rif_min</a>)
1438for the flux-Richardson number. The condition <b>rif_max</b>
1439&gt; <b>rif_min</b>
1440must be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_min"></a><b>rif_min</b></p>
1441</td> <td style="vertical-align: top;">R</td>
1442<td style="vertical-align: top;"><i>- 5.0</i></td>
1443<td style="vertical-align: top;"> <p>Lower limit of
1444the flux-Richardson number.&nbsp; </p> <p>For further
1445explanations see <a href="#rif_max">rif_max</a>.
1446The condition <b>rif_max</b> &gt; <b>rif_min </b>must
1447be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="roughness_length"></a><b>roughness_length</b></p>
1448</td> <td style="vertical-align: top;">R</td>
1449<td style="vertical-align: top;"><i>0.1</i></td>
1450<td style="vertical-align: top;"> <p>Roughness
1451length (in m).&nbsp; </p> <p>This parameter is
1452effective only in case that a Prandtl layer
1453is switched
1454on (see <a href="#prandtl_layer">prandtl_layer</a>).</p>
1455</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="scalar_advec"></a><b>scalar_advec</b></p>
1456</td> <td style="vertical-align: top;">C * 10</td>
1457<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
1458<td style="vertical-align: top;"> <p>Advection
1459scheme to be used for the scalar quantities.&nbsp; </p> <p>The
1460user can choose between the following schemes:<br> </p> <p><span style="font-style: italic;">'pw-scheme'</span><br>
1461</p> <div style="margin-left: 40px;">The scheme of
1462Piascek and
1463Williams (1970, J. Comp. Phys., 6,
1464392-405) with central differences in the form C3 is used.<br>
1465If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
1466= <span style="font-style: italic;">'leapfrog+euler'</span>
1467the
1468advection scheme is - for the Euler-timestep - automatically switched
1469to an upstream-scheme. <br> </div> <br> <p><span style="font-style: italic;">'bc-scheme'</span><br>
1470</p> <div style="margin-left: 40px;">The Bott
1471scheme modified by
1472Chlond (1994, Mon.
1473Wea. Rev., 122, 111-125). This is a conservative monotonous scheme with
1474very small numerical diffusion and therefore very good conservation of
1475scalar flow features. The scheme however, is computationally very
1476expensive both because it is expensive itself and because it does (so
1477far) not allow specific code optimizations (e.g. cache optimization).
1478Choice of this
1479scheme forces the Euler timestep scheme to be used for the scalar
1480quantities. For output of horizontally averaged
1481profiles of the resolved / total heat flux, <a href="chapter_4.2.html#data_output_pr">data_output_pr</a>
1482= <i>'w*pt*BC'</i> / <i>'wptBC' </i>should
1483be used, instead of the
1484standard profiles (<span style="font-style: italic;">'w*pt*'</span>
1485and <span style="font-style: italic;">'wpt'</span>)
1486because these are
1487too inaccurate with this scheme. However, for subdomain analysis (see <a href="#statistic_regions">statistic_regions</a>)
1488exactly the reverse holds: here <i>'w*pt*BC'</i> and <i>'wptBC'</i>
1489show very large errors and should not be used.<br> <br>
1490This scheme is not allowed for non-cyclic lateral boundary conditions
1491(see <a href="#bc_lr">bc_lr</a>
1492and <a href="#bc_ns">bc_ns</a>).<br> <br>
1493</div> <span style="font-style: italic;">'ups-scheme'</span><br>
1494<p style="margin-left: 40px;">The upstream-spline-scheme
1495is used
1496(see Mahrer and Pielke,
14971978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piascek
1498Williams scheme, this is characterized by much better numerical
1499features (less numerical diffusion, better preservation of flux
1500structures, e.g. vortices), but computationally it is much more
1501expensive. In
1502addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
1503= <span style="font-style: italic;">'</span><i>euler'</i>),
1504i.e. the
1505timestep accuracy is only first order. For this reason the advection of
1506momentum (see <a href="#momentum_advec">momentum_advec</a>)
1507should then also be carried out with the upstream-spline scheme,
1508because otherwise the momentum would
1509be subject to large numerical diffusion due to the upstream
1510scheme.&nbsp; </p> <p style="margin-left: 40px;">Since
1511the cubic splines used tend
1512to overshoot under
1513certain circumstances, this effect must be adjusted by suitable
1514filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
1515<a href="#long_filter_factor">long_filter_factor</a>,
1516<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>).
1517This is always neccesssary for runs with stable stratification,
1518even if this stratification appears only in parts of the model
1519domain.&nbsp; </p> <p style="margin-left: 40px;">With
1520stable stratification the
1521upstream-upline scheme also produces gravity waves with large
1522amplitude, which must be
1523suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
1524</p> <p style="margin-left: 40px;"><span style="font-weight: bold;">Important: </span>The&nbsp;
1525upstream-spline scheme is not implemented for humidity and passive
1526scalars (see&nbsp;<a href="#humidity">humidity</a>
1527and <a href="#passive_scalar">passive_scalar</a>)
1528and requires the use of a 2d-domain-decomposition. The last conditions
1529severely restricts code optimization on several machines leading to
1530very long execution times! This scheme is also not allowed for
1531non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
1532and <a href="#bc_ns">bc_ns</a>).</p><br>A
1533differing advection scheme can be choosed for the subgrid-scale TKE
1534using parameter <a href="chapter_4.1.html#use_upstream_for_tke">use_upstream_for_tke</a>.</td>
1535</tr> <tr> <td style="vertical-align: top;">
1536<p><a name="statistic_regions"></a><b>statistic_regions</b></p>
1537</td> <td style="vertical-align: top;">I</td>
1538<td style="vertical-align: top;"><i>0</i></td>
1539<td style="vertical-align: top;"> <p>Number of
1540additional user-defined subdomains for which
1541statistical analysis
1542and corresponding output (profiles, time series) shall be
1543made.&nbsp; </p> <p>By default, vertical profiles and
1544other statistical quantities
1545are calculated as horizontal and/or volume average of the total model
1546domain. Beyond that, these calculations can also be carried out for
1547subdomains which can be defined using the field <a href="chapter_3.5.3.html">rmask </a>within the
1548user-defined software
1549(see <a href="chapter_3.5.3.html">chapter
15503.5.3</a>). The number of these subdomains is determined with the
1551parameter <b>statistic_regions</b>. Maximum 9 additional
1552subdomains
1553are allowed. The parameter <a href="chapter_4.3.html#region">region</a>
1554can be used to assigned names (identifier) to these subdomains which
1555are then used in the headers
1556of the output files and plots.</p><p>If the default NetCDF
1557output format is selected (see parameter <a href="chapter_4.2.html#data_output_format">data_output_format</a>),
1558data for the total domain and all defined subdomains are output to the
1559same file(s) (<a href="chapter_3.4.html#DATA_1D_PR_NETCDF">DATA_1D_PR_NETCDF</a>,
1560<a href="chapter_3.4.html#DATA_1D_TS_NETCDF">DATA_1D_TS_NETCDF</a>).
1561In case of <span style="font-weight: bold;">statistic_regions</span>
1562&gt; <span style="font-style: italic;">0</span>,
1563data on the file for the different domains can be distinguished by a
1564suffix which is appended to the quantity names. Suffix 0 means data for
1565the total domain, suffix 1 means data for subdomain 1, etc.</p><p>In
1566case of <span style="font-weight: bold;">data_output_format</span>
1567= <span style="font-style: italic;">'profil'</span>,
1568individual local files for profiles (<a href="chapter_3.4.html#PLOT1D_DATA">PLOT1D_DATA</a>)&nbsp;are
1569created for each subdomain. The individual subdomain files differ by
1570their name (the
1571number of the respective subdomain is attached, e.g.
1572PLOT1D_DATA_1). In this case the name of the file with the data of
1573the total domain is PLOT1D_DATA_0. If no subdomains
1574are declared (<b>statistic_regions</b> = <i>0</i>),
1575the name
1576PLOT1D_DATA is used (this must be considered in the
1577respective file connection statements of the <span style="font-weight: bold;">mrun</span> configuration
1578file).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_heatflux"></a><b>surface_heatflux</b></p>
1579</td> <td style="vertical-align: top;">R</td>
1580<td style="vertical-align: top;"><span style="font-style: italic;">no prescribed<br>
1581heatflux<br> </span></td> <td style="vertical-align: top;"> <p>Kinematic sensible
1582heat flux at the bottom surface (in K m/s).&nbsp; </p> <p>If
1583a value is assigned to this parameter, the internal two-dimensional
1584surface heat flux field <span style="font-style: italic;">shf</span>
1585is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span>&nbsp;as
1586bottom (horizontally homogeneous) boundary condition for the
1587temperature equation. This additionally requires that a Neumann
1588condition must be used for the potential temperature (see <a href="#bc_pt_b">bc_pt_b</a>),
1589because otherwise the resolved scale may contribute to
1590the surface flux so that a constant value cannot be guaranteed. Also,
1591changes of the
1592surface temperature (see <a href="#pt_surface_initial_change">pt_surface_initial_change</a>)
1593are not allowed. The parameter <a href="#random_heatflux">random_heatflux</a>
1594can be used to impose random perturbations on the (homogeneous) surface
1595heat
1596flux field <span style="font-style: italic;">shf</span>.&nbsp;</p>
1597<p>
1598In case of a non-flat <a href="#topography">topography</a>,&nbsp;the
1599internal two-dimensional&nbsp;surface heat
1600flux field <span style="font-style: italic;">shf</span>
1601is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span>
1602at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
1603at the topography top face.&nbsp;The parameter<a href="#random_heatflux"> random_heatflux</a>
1604can be used to impose random perturbations on this combined surface
1605heat
1606flux field <span style="font-style: italic;">shf</span>.&nbsp;
1607</p> <p>If no surface heat flux is assigned, <span style="font-style: italic;">shf</span> is calculated
1608at each timestep by u<sub>*</sub> * theta<sub>*</sub>
1609(of course only with <a href="#prandtl_layer">prandtl_layer</a>
1610switched on). Here, u<sub>*</sub>
1611and theta<sub>*</sub> are calculated from the Prandtl law
1612assuming
1613logarithmic wind and temperature
1614profiles between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_pt_b">bc_pt_b</a>)
1615must be used as bottom boundary condition for the potential temperature.</p><p>See
1616also <a href="#top_heatflux">top_heatflux</a>.</p>
1617</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_pressure"></a><b>surface_pressure</b></p>
1618</td> <td style="vertical-align: top;">R</td>
1619<td style="vertical-align: top;"><i>1013.25</i></td>
1620<td style="vertical-align: top;"> <p>Atmospheric
1621pressure at the surface (in hPa).&nbsp; </p>
1622Starting from this surface value, the vertical pressure
1623profile is calculated once at the beginning of the run assuming a
1624neutrally stratified
1625atmosphere. This is needed for
1626converting between the liquid water potential temperature and the
1627potential temperature (see <a href="#cloud_physics">cloud_physics</a><span style="text-decoration: underline;"></span>).</td>
1628</tr> <tr> <td style="vertical-align: top;">
1629<p><a name="surface_scalarflux"></a><b>surface_scalarflux</b></p>
1630</td> <td style="vertical-align: top;">R</td>
1631<td style="vertical-align: top;"><i>0.0</i></td>
1632<td style="vertical-align: top;"> <p>Scalar flux at
1633the surface (in kg/(m<sup>2</sup> s)).&nbsp; </p>
1634<p>If a non-zero value is assigned to this parameter, the
1635respective scalar flux value is used
1636as bottom (horizontally homogeneous) boundary condition for the scalar
1637concentration equation.&nbsp;This additionally requires that a
1638Neumann
1639condition must be used for the scalar concentration&nbsp;(see <a href="#bc_s_b">bc_s_b</a>),
1640because otherwise the resolved scale may contribute to
1641the surface flux so that a constant value cannot be guaranteed. Also,
1642changes of the
1643surface scalar concentration (see <a href="#s_surface_initial_change">s_surface_initial_change</a>)
1644are not allowed. <br> </p> <p>If no surface scalar
1645flux is assigned (<b>surface_scalarflux</b>
1646= <i>0.0</i>),
1647it is calculated at each timestep by u<sub>*</sub> * s<sub>*</sub>
1648(of course only with Prandtl layer switched on). Here, s<sub>*</sub>
1649is calculated from the Prandtl law assuming a logarithmic scalar
1650concentration
1651profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_s_b">bc_s_b</a>)
1652must be used as bottom boundary condition for the scalar concentration.</p>
1653</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_waterflux"></a><b>surface_waterflux</b></p>
1654</td> <td style="vertical-align: top;">R</td>
1655<td style="vertical-align: top;"><i>0.0</i></td>
1656<td style="vertical-align: top;"> <p>Kinematic
1657water flux near the surface (in m/s).&nbsp; </p> <p>If
1658a non-zero value is assigned to this parameter, the
1659respective water flux value is used
1660as bottom (horizontally homogeneous) boundary condition for the
1661humidity equation. This additionally requires that a Neumann
1662condition must be used for the specific humidity / total water content
1663(see <a href="#bc_q_b">bc_q_b</a>),
1664because otherwise the resolved scale may contribute to
1665the surface flux so that a constant value cannot be guaranteed. Also,
1666changes of the
1667surface humidity (see <a href="#q_surface_initial_change">q_surface_initial_change</a>)
1668are not allowed.<br> </p> <p>If no surface water
1669flux is assigned (<b>surface_waterflux</b>
1670= <i>0.0</i>),
1671it is calculated at each timestep by u<sub>*</sub> * q<sub>*</sub>
1672(of course only with Prandtl layer switched on). Here, q<sub>*</sub>
1673is calculated from the Prandtl law assuming a logarithmic temperature
1674profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_q_b">bc_q_b</a>)
1675must be used as the bottom boundary condition for the humidity.</p>
1676</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_surface"></a><b>s_surface</b></p>
1677</td> <td style="vertical-align: top;">R</td>
1678<td style="vertical-align: top;"><i>0.0</i></td>
1679<td style="vertical-align: top;"> <p>Surface value
1680of the passive scalar (in kg/m<sup>3</sup>).&nbsp;<br>
1681</p>
1682This parameter assigns the value of the passive scalar s at
1683the surface (k=0)<b>.</b> Starting from this value, the
1684initial vertical scalar concentration profile is constructed with<a href="#s_vertical_gradient">
1685s_vertical_gradient</a> and <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.</td>
1686</tr> <tr> <td style="vertical-align: top;">
1687<p><a name="s_surface_initial_change"></a><b>s_surface_initial</b>
1688<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><i>0.0</i></td>
1689<td style="vertical-align: top;"> <p>Change in
1690surface scalar concentration to be made at the
1691beginning of the 3d run (in kg/m<sup>3</sup>).&nbsp; </p>
1692<p>If <b>s_surface_initial_change</b><i>&nbsp;</i>is
1693set to a
1694non-zero
1695value, the near surface scalar flux is not allowed to be given
1696simultaneously (see <a href="#surface_scalarflux">surface_scalarflux</a>).</p>
1697</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient"></a><b>s_vertical_gradient</b></p>
1698</td> <td style="vertical-align: top;">R (10)</td>
1699<td style="vertical-align: top;"><i>10 * 0</i><i>.0</i></td>
1700<td style="vertical-align: top;"> <p>Scalar
1701concentration gradient(s) of the initial scalar
1702concentration profile (in kg/m<sup>3 </sup>/
1703100 m).&nbsp; </p> <p>The scalar gradient holds
1704starting from the height level
1705defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level
1706</a>(precisely: for all uv levels k, where zu(k) &gt;
1707s_vertical_gradient_level, s_init(k) is set: s_init(k) = s_init(k-1) +
1708dzu(k) * <b>s_vertical_gradient</b>) up to the top
1709boundary or up to
1710the next height level defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
1711A total of 10 different gradients for 11 height intervals (10 intervals
1712if <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>(1)
1713= <i>0.0</i>) can be assigned. The surface scalar value is
1714assigned
1715via <a href="#s_surface">s_surface</a>.<br> </p>
1716<p>Example:&nbsp; </p> <ul> <p><b>s_vertical_gradient</b>
1717= <i>0.1</i>, <i>0.05</i>,&nbsp; <br>
1718<b>s_vertical_gradient_level</b> = <i>500.0</i>,
1719<i>1000.0</i>,</p> </ul> <p>That
1720defines the scalar concentration to be constant with
1721height up to z = 500.0 m with a value given by <a href="#s_surface">s_surface</a>.
1722For 500.0 m &lt; z &lt;= 1000.0 m the scalar gradient is 0.1
1723kg/m<sup>3 </sup>/ 100 m and for z &gt; 1000.0 m up to
1724the top
1725boundary it is 0.05 kg/m<sup>3 </sup>/ 100 m (it is
1726assumed that the
1727assigned height levels
1728correspond with uv
1729levels).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient_level"></a><b>s_vertical_gradient_</b>
1730<br> <b>level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>
1731<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
1732which on the scalar gradient defined by <a href="#s_vertical_gradient">s_vertical_gradient</a>
1733is effective (in m).&nbsp; </p> <p>The height levels
1734are to be assigned in ascending order. The
1735default values result in a scalar concentration constant with height
1736regardless of the values of <a href="#s_vertical_gradient">s_vertical_gradient</a>
1737(unless the top boundary of the model is higher than 100000.0 m). For
1738the
1739piecewise construction of scalar concentration profiles see <a href="#s_vertical_gradient">s_vertical_gradient</a>.</p>
1740</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="timestep_scheme"></a><b>timestep_scheme</b></p>
1741</td> <td style="vertical-align: top;">C * 20</td>
1742<td style="vertical-align: top;"> <p><i>'runge</i><br>
1743<i>kutta-3'</i></p> </td> <td style="vertical-align: top;"> <p>Time step scheme to
1744be used for the integration of the prognostic
1745variables.&nbsp; </p> <p>The user can choose between
1746the following schemes:<br> </p> <p><span style="font-style: italic;">'runge-kutta-3'</span><br>
1747</p> <div style="margin-left: 40px;">Third order
1748Runge-Kutta scheme.<br>
1749This scheme requires the use of <a href="#momentum_advec">momentum_advec</a>
1750= <a href="#scalar_advec">scalar_advec</a>
1751= '<i>pw-scheme'</i>. Please refer to the&nbsp;<a href="../tec/numerik.heiko/zeitschrittverfahren.pdf">documentation
1752on PALM's time integration schemes&nbsp;(28p., in German)</a>
1753fur further details.<br> </div> <p><span style="font-style: italic;">'runge-kutta-2'</span><br>
1754</p> <div style="margin-left: 40px;">Second order
1755Runge-Kutta scheme.<br>
1756For special features see <b>timestep_scheme</b> = '<i>runge-kutta-3'</i>.<br>
1757</div> <br> <span style="font-style: italic;"><span style="font-style: italic;">'leapfrog'</span><br>
1758<br> </span> <div style="margin-left: 40px;">Second
1759order leapfrog scheme.<br>
1760Although this scheme requires a constant timestep (because it is
1761centered in time),&nbsp; is even applied in case of changes in
1762timestep. Therefore, only small
1763changes of the timestep are allowed (see <a href="#dt">dt</a>).
1764However, an Euler timestep is always used as the first timestep of an
1765initiali run. When using the Bott-Chlond scheme for scalar advection
1766(see <a href="#scalar_advec">scalar_advec</a>),
1767the prognostic equation for potential temperature will be calculated
1768with the Euler scheme, although the leapfrog scheme is switched
1769on.&nbsp; <br>
1770The leapfrog scheme must not be used together with the upstream-spline
1771scheme for calculating the advection (see <a href="#scalar_advec">scalar_advec</a>
1772= '<i>ups-scheme'</i> and <a href="#momentum_advec">momentum_advec</a>
1773= '<i>ups-scheme'</i>).<br> </div> <br>
1774<span style="font-style: italic;">'</span><span style="font-style: italic;"><span style="font-style: italic;">leapfrog+euler'</span><br>
1775<br> </span> <div style="margin-left: 40px;">The
1776leapfrog scheme is used, but
1777after each change of a timestep an Euler timestep is carried out.
1778Although this method is theoretically correct (because the pure
1779leapfrog method does not allow timestep changes), the divergence of the
1780velocity field (after applying the pressure solver) may be
1781significantly larger than with <span style="font-style: italic;">'leapfrog'</span>.<br>
1782</div> <br> <span style="font-style: italic;">'euler'</span><br>
1783<br> <div style="margin-left: 40px;">First order
1784Euler scheme.&nbsp; <br>
1785The Euler scheme must be used when treating the advection terms with
1786the upstream-spline scheme (see <a href="#scalar_advec">scalar_advec</a>
1787= <span style="font-style: italic;">'ups-scheme'</span>
1788and <a href="#momentum_advec">momentum_advec</a>
1789= <span style="font-style: italic;">'ups-scheme'</span>).</div>
1790<br><br>A differing timestep scheme can be choosed for the
1791subgrid-scale TKE using parameter <a href="#use_upstream_for_tke">use_upstream_for_tke</a>.<br>
1792</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>
1793<td style="vertical-align: top;">C * 40</td> <td style="vertical-align: top;"><span style="font-style: italic;">'flat'</span></td> <td>
1794<p>Topography mode.&nbsp; </p> <p>The user can
1795choose between the following modes:<br> </p> <p><span style="font-style: italic;">'flat'</span><br> </p>
1796<div style="margin-left: 40px;">Flat surface.</div> <p><span style="font-style: italic;">'single_building'</span><br>
1797</p> <div style="margin-left: 40px;">Flow
1798around&nbsp;a single rectangular building mounted on a flat surface.<br>
1799The 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>
1800<span style="font-style: italic;"></span> <p><span style="font-style: italic;">'read_from_file'</span><br>
1801</p> <div style="margin-left: 40px;">Flow around
1802arbitrary topography.<br>
1803This 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
1804information</font></font><font color="#000000">
1805in m. These data&nbsp;<span style="font-style: italic;"></span>must
1806exactly match the horizontal grid.</font> </div> <span style="font-style: italic;"><br> </span><font color="#000000">
1807Alternatively, the user may add code to the user interface subroutine <a href="chapter_3.5.1.html#user_init_grid">user_init_grid</a>
1808to allow further topography modes.<br> <br>
1809All non-flat <span style="font-weight: bold;">topography</span>
1810modes </font>require the use of <a href="#momentum_advec">momentum_advec</a>
1811= <a href="#scalar_advec">scalar_advec</a>
1812= '<i>pw-scheme'</i>, <a href="chapter_4.2.html#psolver">psolver</a>
1813= <i>'poisfft'</i> or '<i>poisfft_hybrid'</i>,
1814<i>&nbsp;</i><a href="#alpha_surface">alpha_surface</a>
1815= 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>
1816= <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;&nbsp;<a href="#humidity">humidity</a> = <span style="font-style: italic;">.F.</span>, and <a href="#prandtl_layer">prandtl_layer</a> = .T..<br>
1817<font color="#000000"><br>
1818Note 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
1819nonzero </font><a href="#alpha_surface">alpha_surface</a>.</td>
1820</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>
1821heatflux</span></td><td style="vertical-align: top;"><p>Kinematic
1822sensible heat flux at the top boundary (in K m/s).&nbsp; </p>
1823<p>If a value is assigned to this parameter, the internal
1824two-dimensional surface heat flux field <span style="font-family: monospace;">tswst</span> is
1825initialized with the value of <span style="font-weight: bold;">top_heatflux</span>&nbsp;as
1826top (horizontally homogeneous) boundary condition for the
1827temperature equation. This additionally requires that a Neumann
1828condition must be used for the potential temperature (see <a href="chapter_4.1.html#bc_pt_t">bc_pt_t</a>),
1829because otherwise the resolved scale may contribute to
1830the top flux so that a constant value cannot be guaranteed.<span style="font-style: italic;"></span>&nbsp;</p>
1831<p><span style="font-weight: bold;">Note:</span><br>The
1832application of a top heat flux additionally requires the setting of
1833initial parameter <a href="#use_top_fluxes">use_top_fluxes</a>
1834= .T..<span style="font-style: italic;"></span><span style="font-weight: bold;"></span> </p><p>No
1835Prandtl-layer is available at the top boundary so far.</p><p>See
1836also <a href="#surface_heatflux">surface_heatflux</a>.</p>
1837</td></tr><tr> <td style="vertical-align: top;">
1838<p><a name="ug_surface"></a><span style="font-weight: bold;">ug_surface</span></p>
1839</td> <td style="vertical-align: top;">R<br> </td>
1840<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
1841<td style="vertical-align: top;">u-component of the
1842geostrophic
1843wind at the surface (in m/s).<br> <br>
1844This parameter assigns the value of the u-component of the geostrophic
1845wind (ug) at the surface (k=0). Starting from this value, the initial
1846vertical profile of the <br>
1847u-component of the geostrophic wind is constructed with <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
1848and <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
1849The
1850profile constructed in that way is used for creating the initial
1851vertical velocity profile of the 3d-model. Either it is applied, as it
1852has been specified by the user (<a href="#initializing_actions">initializing_actions</a>
1853= 'set_constant_profiles') or it is used for calculating a stationary
1854boundary layer wind profile (<a href="#initializing_actions">initializing_actions</a>
1855= 'set_1d-model_profiles'). If ug is constant with height (i.e. ug(k)=<span style="font-weight: bold;">ug_surface</span>)
1856and&nbsp; has a large
1857value, it is recommended to use a Galilei-transformation of the
1858coordinate system, if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
1859in order to obtain larger time steps.<br> </td> </tr>
1860<tr> <td style="vertical-align: top;"> <p><a name="ug_vertical_gradient"></a><span style="font-weight: bold;">ug_vertical_gradient</span></p>
1861</td> <td style="vertical-align: top;">R(10)<br>
1862</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
1863* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
1864profile of the&nbsp; u-component of the geostrophic wind (in
18651/100s).<br> <br>
1866The gradient holds starting from the height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
1867(precisely: for all uv levels k where zu(k) &gt; <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>,
1868ug(k) is set: ug(k) = ug(k-1) + dzu(k) * <span style="font-weight: bold;">ug_vertical_gradient</span>)
1869up to the top
1870boundary or up to the next height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
1871A
1872total of 10 different gradients for 11 height intervals (10
1873intervals&nbsp; if <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>(1)
1874= 0.0) can be assigned. The surface geostrophic wind is assigned by <a href="#ug_surface">ug_surface</a>. <br> </td>
1875</tr> <tr> <td style="vertical-align: top;">
1876<p><a name="ug_vertical_gradient_level"></a><span style="font-weight: bold;">ug_vertical_gradient_level</span></p>
1877</td> <td style="vertical-align: top;">R(10)<br>
1878</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
1879* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
1880gradient defined by <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
1881is effective (in m).<br> <br>
1882The height levels are to be assigned in ascending order. For the
1883piecewise construction of a profile of the u-component of the
1884geostrophic wind component (ug) see <a href="#ug_vertical_gradient">ug_vertical_gradient</a>.<br>
1885</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_e"></a><b>ups_limit_e</b></p>
1886</td> <td style="vertical-align: top;">R</td>
1887<td style="vertical-align: top;"><i>0.0</i></td>
1888<td style="vertical-align: top;"> <p>Subgrid-scale
1889turbulent kinetic energy difference used as
1890criterion for applying the upstream scheme when upstream-spline
1891advection is switched on (in m<sup>2</sup>/s<sup>2</sup>).
1892&nbsp; </p> <p>This variable steers the appropriate
1893treatment of the
1894advection of the subgrid-scale turbulent kinetic energy in case that
1895the uptream-spline scheme is used . For further information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp; </p>
1896<p>Only positive values are allowed for <b>ups_limit_e</b>.
1897</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_pt"></a><b>ups_limit_pt</b></p>
1898</td> <td style="vertical-align: top;">R</td>
1899<td style="vertical-align: top;"><i>0.0</i></td>
1900<td style="vertical-align: top;"> <p>Temperature
1901difference used as criterion for applying&nbsp;
1902the upstream scheme when upstream-spline advection&nbsp; is
1903switched on
1904(in K).&nbsp; </p> <p>This criterion is used if the
1905upstream-spline scheme is
1906switched on (see <a href="#scalar_advec">scalar_advec</a>).<br>
1907If, for a given gridpoint, the absolute temperature difference with
1908respect to the upstream
1909grid point is smaller than the value given for <b>ups_limit_pt</b>,
1910the upstream scheme is used for this gridpoint (by default, the
1911upstream-spline scheme is always used). Reason: in case of a very small
1912upstream gradient, the advection should cause only a very small
1913tendency. However, in such situations the upstream-spline scheme may
1914give wrong tendencies at a
1915grid point due to spline overshooting, if simultaneously the downstream
1916gradient is very large. In such cases it may be more reasonable to use
1917the upstream scheme. The numerical diffusion caused by the upstream
1918schme remains small as long as the upstream gradients are small.<br>
1919</p> <p>The percentage of grid points for which the
1920upstream
1921scheme is actually used, can be output as a time series with respect to
1922the
1923three directions in space with run parameter (see <a href="chapter_4.2.html#dt_dots">dt_dots</a>, the
1924timeseries names in the NetCDF file are <i>'splptx'</i>, <i>'splpty'</i>,
1925<i>'splptz'</i>). The percentage
1926of gridpoints&nbsp; should stay below a certain limit, however, it
1927is
1928not possible to give
1929a general limit, since it depends on the respective flow.&nbsp; </p>
1930<p>Only positive values are permitted for <b>ups_limit_pt</b>.<br>
1931</p>
1932A more effective control of
1933the &ldquo;overshoots&rdquo; can be achieved with parameter <a href="#cut_spline_overshoot">cut_spline_overshoot</a>.
1934</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_u"></a><b>ups_limit_u</b></p>
1935</td> <td style="vertical-align: top;">R</td>
1936<td style="vertical-align: top;"><i>0.0</i></td>
1937<td style="vertical-align: top;"> <p>Velocity
1938difference (u-component) used as criterion for
1939applying the upstream scheme
1940when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1941<p>This variable steers the appropriate treatment of the
1942advection of the u-velocity-component in case that the upstream-spline
1943scheme is used. For further
1944information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1945</p> <p>Only positive values are permitted for <b>ups_limit_u</b>.</p>
1946</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_v"></a><b>ups_limit_v</b></p>
1947</td> <td style="vertical-align: top;">R</td>
1948<td style="vertical-align: top;"><i>0.0</i></td>
1949<td style="vertical-align: top;"> <p>Velocity
1950difference (v-component) used as criterion for
1951applying the upstream scheme
1952when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1953<p>This variable steers the appropriate treatment of the
1954advection of the v-velocity-component in case that the upstream-spline
1955scheme is used. For further
1956information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1957</p> <p>Only positive values are permitted for <b>ups_limit_v</b>.</p>
1958</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_w"></a><b>ups_limit_w</b></p>
1959</td> <td style="vertical-align: top;">R</td>
1960<td style="vertical-align: top;"><i>0.0</i></td>
1961<td style="vertical-align: top;"> <p>Velocity
1962difference (w-component) used as criterion for
1963applying the upstream scheme
1964when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1965<p>This variable steers the appropriate treatment of the
1966advection of the w-velocity-component in case that the upstream-spline
1967scheme is used. For further
1968information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1969</p> <p>Only positive values are permitted for <b>ups_limit_w</b>.</p>
1970</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="use_surface_fluxes"></a><b>use_surface_fluxes</b></p>
1971</td> <td style="vertical-align: top;">L</td>
1972<td style="vertical-align: top;"><i>.F.</i></td>
1973<td style="vertical-align: top;"> <p>Parameter to
1974steer the treatment of the subgrid-scale vertical
1975fluxes within the diffusion terms at k=1 (bottom boundary).<br> </p>
1976<p>By default, the near-surface subgrid-scale fluxes are
1977parameterized (like in the remaining model domain) using the gradient
1978approach. If <b>use_surface_fluxes</b>
1979= <i>.TRUE.</i>, the user-assigned surface fluxes are used
1980instead
1981(see <a href="#surface_heatflux">surface_heatflux</a>,
1982<a href="#surface_waterflux">surface_waterflux</a>
1983and <a href="#surface_scalarflux">surface_scalarflux</a>)
1984<span style="font-weight: bold;">or</span> the
1985surface fluxes are
1986calculated via the Prandtl layer relation (depends on the bottom
1987boundary conditions, see <a href="#bc_pt_b">bc_pt_b</a>,
1988<a href="#bc_q_b">bc_q_b</a>
1989and <a href="#bc_s_b">bc_s_b</a>).<br> </p>
1990<p><b>use_surface_fluxes</b>
1991is automatically set <i>.TRUE.</i>, if a Prandtl layer is
1992used (see <a href="#prandtl_layer">prandtl_layer</a>).&nbsp;
1993</p> <p>The user may prescribe the surface fluxes at the
1994bottom
1995boundary without using a Prandtl layer by setting <span style="font-weight: bold;">use_surface_fluxes</span> =
1996<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
1997case, the
1998momentum flux (u<sub>*</sub><sup>2</sup>)
1999should also be prescribed,
2000the user must assign an appropriate value within the user-defined code.</p>
2001</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
2002the treatment of the subgrid-scale vertical
2003fluxes within the diffusion terms at k=nz (top boundary).</p><p>By
2004default, the fluxes at nz are calculated using the gradient approach.
2005If <b>use_top_fluxes</b>
2006= <i>.TRUE.</i>, the user-assigned top fluxes are used
2007instead
2008(see <a href="chapter_4.1.html#top_heatflux">top_heatflux</a>).</p><p>Currently,
2009only 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
2010heat flux at the top will be automatically set to zero.</p></td></tr><tr>
2011<td style="vertical-align: top;"> <p><a name="use_ug_for_galilei_tr"></a><b>use_ug_for_galilei_tr</b></p>
2012</td> <td style="vertical-align: top;">L</td>
2013<td style="vertical-align: top;"><i>.T.</i></td>
2014<td style="vertical-align: top;"> <p>Switch to
2015determine the translation velocity in case that a
2016Galilean transformation is used.<br> </p> <p>In
2017case of a Galilean transformation (see <a href="#galilei_transformation">galilei_transformation</a>),
2018<b>use_ug_for_galilei_tr</b>
2019= <i>.T.</i>&nbsp; ensures
2020that the coordinate system is translated with the geostrophic windspeed.<br>
2021</p> <p>Alternatively, with <b>use_ug_for_galilei_tr</b>
2022= <i>.F</i>.,
2023the
2024geostrophic wind can be replaced as translation speed by the (volume)
2025averaged velocity. However, in this case the user must be aware of fast
2026growing gravity waves, so this
2027choice 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
2028advection/timestep scheme to be used for the subgrid-scale TKE.<br><br>By
2029default, the advection scheme and the timestep scheme to be used for
2030the subgrid-scale TKE are set by the initialization parameters <a href="#scalar_advec">scalar_advec</a> and <a href="#timestep_scheme">timestep_scheme</a>,
2031respectively. <span style="font-weight: bold;">use_upstream_for_tke</span>
2032= <span style="font-style: italic;">.T.</span>
2033forces the Euler-scheme and the upstream-scheme to be used as timestep
2034scheme and advection scheme, respectively. By these methods, the strong
2035(artificial) near-surface vertical gradients of the subgrid-scale TKE
2036are significantly reduced. This is required when subgrid-scale
2037velocities are used for advection of particles (see particle package
2038parameter <a href="chapter_4.2.html#use_sgs_for_particles">use_sgs_for_particles</a>).</td></tr><tr>
2039<td style="vertical-align: top;"> <p><a name="vg_surface"></a><span style="font-weight: bold;">vg_surface</span></p>
2040</td> <td style="vertical-align: top;">R<br> </td>
2041<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
2042<td style="vertical-align: top;">v-component of the
2043geostrophic
2044wind at the surface (in m/s).<br> <br>
2045This parameter assigns the value of the v-component of the geostrophic
2046wind (vg) at the surface (k=0). Starting from this value, the initial
2047vertical profile of the <br>
2048v-component of the geostrophic wind is constructed with <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
2049and <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
2050The
2051profile
2052constructed in that way is used for creating the initial vertical
2053velocity profile of the 3d-model. Either it is applied, as it has been
2054specified by the user (<a href="#initializing_actions">initializing_actions</a>
2055= 'set_constant_profiles')
2056or it is used for calculating a stationary boundary layer wind profile
2057(<a href="#initializing_actions">initializing_actions</a>
2058=
2059'set_1d-model_profiles'). If vg is constant
2060with height (i.e. vg(k)=<span style="font-weight: bold;">vg_surface</span>)
2061and&nbsp; has a large value, it is
2062recommended to use a Galilei-transformation of the coordinate system,
2063if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
2064in order to obtain larger
2065time 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>
2066</td> <td style="vertical-align: top;">R(10)<br>
2067</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
2068* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
2069profile of the&nbsp; v-component of the geostrophic wind (in
20701/100s).<br> <br>
2071The gradient holds starting from the height level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>
2072(precisely: for all uv levels k where zu(k)
2073&gt; <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
2074vg(k) is set: vg(k) = vg(k-1) + dzu(k)
2075* <span style="font-weight: bold;">vg_vertical_gradient</span>)
2076up to
2077the top boundary or up to the next height
2078level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
2079A total of 10 different
2080gradients for 11 height intervals (10 intervals&nbsp; if <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>(1)
2081=
20820.0) can be assigned. The surface
2083geostrophic wind is assigned by <a href="#vg_surface">vg_surface</a>.</td>
2084</tr> <tr> <td style="vertical-align: top;">
2085<p><a name="vg_vertical_gradient_level"></a><span style="font-weight: bold;">vg_vertical_gradient_level</span></p>
2086</td> <td style="vertical-align: top;">R(10)<br>
2087</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
2088* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
2089gradient defined by <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
2090is effective (in m).<br> <br>
2091The height levels are to be assigned in ascending order. For the
2092piecewise construction of a profile of the v-component of the
2093geostrophic wind component (vg) see <a href="#vg_vertical_gradient">vg_vertical_gradient</a>.</td>
2094</tr> <tr> <td style="vertical-align: top;">
2095<p><a name="wall_adjustment"></a><b>wall_adjustment</b></p>
2096</td> <td style="vertical-align: top;">L</td>
2097<td style="vertical-align: top;"><i>.T.</i></td>
2098<td style="vertical-align: top;"> <p>Parameter to
2099restrict the mixing length in the vicinity of the
2100bottom
2101boundary.&nbsp; </p> <p>With <b>wall_adjustment</b>
2102= <i>.TRUE., </i>the mixing
2103length is limited to a maximum of&nbsp; 1.8 * z. This condition
2104typically affects only the
2105first grid points above the bottom boundary.</p> </td> </tr>
2106<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="wall_heatflux"></a>wall_heatflux</span></td>
2107<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
2108kinematic sensible heat flux in W m<sup>-2</sup>
2109at the five topography faces:<br> <br> <div style="margin-left: 40px;"><span style="font-weight: bold;">wall_heatflux(0)&nbsp;&nbsp;
2110&nbsp;</span>top face<br> <span style="font-weight: bold;">wall_heatflux(1)&nbsp;&nbsp;&nbsp;
2111</span>left face<br> <span style="font-weight: bold;">wall_heatflux(2)&nbsp;&nbsp;&nbsp;
2112</span>right face<br> <span style="font-weight: bold;">wall_heatflux(3)&nbsp;&nbsp;&nbsp;
2113</span>south face<br> <span style="font-weight: bold;">wall_heatflux(4)&nbsp;&nbsp;&nbsp;
2114</span>north face</div> <br>
2115This parameter applies only in case of a non-flat <a href="#topography">topography</a>.&nbsp;The
2116parameter <a href="#random_heatflux">random_heatflux</a>
2117can be used to impose random perturbations on the internal
2118two-dimensional surface heat
2119flux field <span style="font-style: italic;">shf</span>
2120that is composed of <a href="#surface_heatflux">surface_heatflux</a>
2121at the bottom surface and <span style="font-weight: bold;">wall_heatflux(0)</span>
2122at the topography top face.&nbsp;</td> </tr> </tbody>
2123</table><br>
2124<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>
2125<p style="line-height: 100%;"><i>Last
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2127<br><br>
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