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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 x-direction (in m).&nbsp; </p> <p>Along
562x-direction only a constant grid spacing is allowed.</p> </td>
563</tr> <tr> <td style="vertical-align: top;">
564<p><a name="dz"></a><b>dz</b></p>
565</td> <td style="vertical-align: top;">R</td>
566<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Vertical grid
567spacing (in m).&nbsp; </p> <p>This parameter must be
568assigned by the user, because no
569default value is given.<br> </p> <p>By default, the
570model uses constant grid spacing along z-direction, but it can be
571stretched using the parameters <a href="#dz_stretch_level">dz_stretch_level</a>
572and <a href="#dz_stretch_factor">dz_stretch_factor</a>.
573In case of stretching, a maximum allowed grid spacing can be given by <a href="#dz_max">dz_max</a>.<br> </p> <p>Assuming
574a constant <span style="font-weight: bold;">dz</span>,
575the scalar levels (zu) are calculated directly by:&nbsp; </p>
576<ul> <p>zu(0) = - dz * 0.5&nbsp; <br>
577zu(1) = dz * 0.5</p> </ul> <p>The w-levels lie
578half between them:&nbsp; </p> <ul> <p>zw(k) =
579( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
580<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
581spacing (in m).<br><br>If the vertical grid is stretched
582(see <a href="#dz_stretch_factor">dz_stretch_factor</a>
583and <a href="#dz_stretch_level">dz_stretch_level</a>),
584<span style="font-weight: bold;">dz_max</span> can
585be used to limit the vertical grid spacing.</td></tr><tr>
586<td style="vertical-align: top;"> <p><a name="dz_stretch_factor"></a><b>dz_stretch_factor</b></p>
587</td> <td style="vertical-align: top;">R</td>
588<td style="vertical-align: top;"><span style="font-style: italic;">1.08</span></td> <td style="vertical-align: top;"> <p>Stretch factor for a
589vertically stretched grid (see <a href="#dz_stretch_level">dz_stretch_level</a>).&nbsp;
590</p> <p>The stretch factor should not exceed a value of
591approx. 1.10 -
5921.12, otherwise the discretization errors due to the stretched grid not
593negligible any more. (refer Kalnay de Rivas)</p> </td> </tr>
594<tr> <td style="vertical-align: top;"> <p><a name="dz_stretch_level"></a><b>dz_stretch_level</b></p>
595</td> <td style="vertical-align: top;">R</td>
596<td style="vertical-align: top;"><span style="font-style: italic;">100000.0</span><br> </td>
597<td style="vertical-align: top;"> <p>Height level
598above which the grid is to be stretched
599vertically (in m).&nbsp; </p> <p>The vertical grid
600spacings <a href="#dz">dz</a>
601above this level are calculated as&nbsp; </p> <ul> <p><b>dz</b>(k+1)
602= <b>dz</b>(k) * <a href="#dz_stretch_factor">dz_stretch_factor</a></p>
603</ul> <p>and used as spacings for the scalar levels (zu).
604The
605w-levels are then defined as:&nbsp; </p> <ul> <p>zw(k)
606= ( zu(k) + zu(k+1) ) * 0.5</p> </ul> </td> </tr>
607<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="e_min"></a>e_min</span></td>
608<td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><span style="font-style: italic;">0.0</span></td> <td>Minimum
609subgrid-scale TKE in m<sup>2</sup>s<sup>-2</sup>.<br>
610<br>This
611option&nbsp;adds artificial viscosity to the flow by ensuring that
612the
613subgrid-scale TKE does not fall below the minimum threshold <span style="font-weight: bold;">e_min</span>.</td> </tr>
614<tr> <td style="vertical-align: top;"> <p><a name="end_time_1d"></a><b>end_time_1d</b></p>
615</td> <td style="vertical-align: top;">R</td>
616<td style="vertical-align: top;"><span style="font-style: italic;">864000.0</span><br> </td>
617<td style="vertical-align: top;"> <p>Time to be
618simulated for the 1d-model (in s).&nbsp; </p> <p>The
619default value corresponds to a simulated time of 10 days.
620Usually, after such a period the inertia oscillations have completely
621decayed and the solution of the 1d-model can be regarded as stationary
622(see <a href="#damp_level_1d">damp_level_1d</a>).
623This parameter is only in effect if the 1d-model is switched on for the
624initialization of the 3d-model with <a href="#initializing_actions">initializing_actions</a>
625= <span style="font-style: italic;">'set_1d-model_profiles'</span>.</p>
626</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="fft_method"></a><b>fft_method</b></p>
627</td> <td style="vertical-align: top;">C * 20</td>
628<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>
629<td style="vertical-align: top;"> <p>FFT-method to
630be used.<br> </p> <p><br>
631The fast fourier transformation (FFT) is used for solving the
632perturbation pressure equation with a direct method (see <a href="chapter_4.2.html#psolver">psolver</a>)
633and for calculating power spectra (see optional software packages,
634section <a href="chapter_4.2.html#spectra_package">4.2</a>).</p>
635<p><br>
636By default, system-specific, optimized routines from external
637vendor libraries are used. However, these are available only on certain
638computers and there are more or less severe restrictions concerning the
639number of gridpoints to be used with them.<br> </p> <p>There
640are two other PALM internal methods available on every
641machine (their respective source code is part of the PALM source code):</p>
642<p>1.: The <span style="font-weight: bold;">Temperton</span>-method
643from Clive Temperton (ECWMF) which is computationally very fast and
644switched on with <b>fft_method</b> = <span style="font-style: italic;">'temperton-algorithm'</span>.
645The number of horizontal gridpoints (nx+1, ny+1) to be used with this
646method must be composed of prime factors 2, 3 and 5.<br> </p>
6472.: The <span style="font-weight: bold;">Singleton</span>-method
648which is very slow but has no restrictions concerning the number of
649gridpoints to be used with, switched on with <b>fft_method</b>
650= <span style="font-style: italic;">'singleton-algorithm'</span>.
651</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="galilei_transformation"></a><b>galilei_transformation</b></p>
652</td> <td style="vertical-align: top;">L</td>
653<td style="vertical-align: top;"><i>.F.</i></td>
654<td style="vertical-align: top;">Application of a
655Galilei-transformation to the
656coordinate
657system of the model.<br><p>With <b>galilei_transformation</b>
658= <i>.T.,</i> a so-called
659Galilei-transformation is switched on which ensures that the coordinate
660system of the model is moved along with the geostrophical wind.
661Alternatively, the model domain can be moved along with the averaged
662horizontal wind (see <a href="#use_ug_for_galilei_tr">use_ug_for_galilei_tr</a>,
663this can and will naturally change in time). With this method,
664numerical inaccuracies of the Piascek - Williams - scheme (concerns in
665particular the momentum advection) are minimized. Beyond that, in the
666majority of cases the lower relative velocities in the moved system
667permit a larger time step (<a href="#dt">dt</a>).
668Switching the transformation on is only worthwhile if the geostrophical
669wind (ug, vg)
670and the averaged horizontal wind clearly deviate from the value 0. In
671each case, the distance the coordinate system has been moved is written
672to the file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>.&nbsp;
673</p> <p>Non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
674and <a href="#bc_ns">bc_ns</a>), the specification
675of a gestrophic
676wind that is not constant with height
677as well as e.g. stationary inhomogeneities at the bottom boundary do
678not allow the use of this transformation.</p> </td> </tr>
679<tr> <td style="vertical-align: top;"> <p><a name="grid_matching"></a><b>grid_matching</b></p>
680</td> <td style="vertical-align: top;">C * 6</td>
681<td style="vertical-align: top;"><span style="font-style: italic;">'match'</span></td> <td style="vertical-align: top;">Variable to adjust the
682subdomain
683sizes in parallel runs.<br> <br>
684For <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>,
685the subdomains are forced to have an identical
686size on all processors. In this case the processor numbers in the
687respective directions of the virtual processor net must fulfill certain
688divisor conditions concerning the grid point numbers in the three
689directions (see <a href="#nx">nx</a>, <a href="#ny">ny</a>
690and <a href="#nz">nz</a>).
691Advantage of this method is that all PEs bear the same computational
692load.<br> <br>
693There is no such restriction by default, because then smaller
694subdomains are allowed on those processors which
695form the right and/or north boundary of the virtual processor grid. On
696all other processors the subdomains are of same size. Whether smaller
697subdomains are actually used, depends on the number of processors and
698the grid point numbers used. Information about the respective settings
699are 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>
700<br>
701When 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>)
702only <b>grid_matching</b> = <span style="font-style: italic;">'strict'</span>
703is allowed.<br> <br> <b>Note:</b><br>
704In some cases for small processor numbers there may be a very bad load
705balancing among the
706processors which may reduce the performance of the code.</td> </tr>
707<tr> <td style="vertical-align: top;"><a name="inflow_disturbance_begin"></a><b>inflow_disturbance_<br>
708begin</b></td> <td style="vertical-align: top;">I</td>
709<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>
710<td style="vertical-align: top;">Lower
711limit of the horizontal range for which random perturbations are to be
712imposed on the horizontal velocity field (gridpoints).<br> <br>
713If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
714or <a href="#bc_ns">bc_ns</a>),
715this parameter gives the gridpoint number (counted horizontally from
716the inflow)&nbsp; from which on perturbations are imposed on the
717horizontal velocity field. Perturbations must be switched on with
718parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
719</tr> <tr> <td style="vertical-align: top;"><a name="inflow_disturbance_end"></a><b>inflow_disturbance_<br>
720end</b></td> <td style="vertical-align: top;">I</td>
721<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
722limit of the horizontal range for which random perturbations are
723to be imposed on the horizontal velocity field (gridpoints).<br> <br>
724If non-cyclic lateral boundary conditions are used (see <a href="#bc_lr">bc_lr</a>
725or <a href="#bc_ns">bc_ns</a>),
726this parameter gives the gridpoint number (counted horizontally from
727the inflow)&nbsp; unto which perturbations are imposed on the
728horizontal
729velocity field. Perturbations must be switched on with parameter <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>.</td>
730</tr> <tr> <td style="vertical-align: top;">
731<p><a name="initializing_actions"></a><b>initializing_actions</b></p>
732</td> <td style="vertical-align: top;">C * 100</td>
733<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p style="font-style: normal;">Initialization actions
734to be carried out.&nbsp; </p> <p style="font-style: normal;">This parameter does not have a
735default value and therefore must be assigned with each model run. For
736restart runs <b>initializing_actions</b> = <span style="font-style: italic;">'read_restart_data'</span>
737must be set. For the initial run of a job chain the following values
738are allowed:&nbsp; </p> <p style="font-style: normal;"><span style="font-style: italic;">'set_constant_profiles'</span>
739</p> <ul> <p>A horizontal wind profile consisting
740of linear sections (see <a href="#ug_surface">ug_surface</a>,
741<a href="#ug_vertical_gradient">ug_vertical_gradient</a>,
742<a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
743and <a href="#vg_surface">vg_surface</a>, <a href="#vg_vertical_gradient">vg_vertical_gradient</a>,
744<a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
745respectively) as well as a vertical temperature (humidity) profile
746consisting of
747linear sections (see <a href="#pt_surface">pt_surface</a>,
748<a href="#pt_vertical_gradient">pt_vertical_gradient</a>,
749<a href="#q_surface">q_surface</a>
750and <a href="#q_vertical_gradient">q_vertical_gradient</a>)
751are assumed as initial profiles. The subgrid-scale TKE is set to 0 but K<sub>m</sub>
752and K<sub>h</sub> are set to very small values because
753otherwise no TKE
754would be generated.</p> </ul> <p style="font-style: italic;">'set_1d-model_profiles' </p>
755<ul> <p>The arrays of the 3d-model are initialized with
756the
757(stationary) solution of the 1d-model. These are the variables e, kh,
758km, u, v and with Prandtl layer switched on rif, us, usws, vsws. The
759temperature (humidity) profile consisting of linear sections is set as
760for 'set_constant_profiles' and assumed as constant in time within the
7611d-model. For steering of the 1d-model a set of parameters with suffix
762"_1d" (e.g. <a href="#end_time_1d">end_time_1d</a>,
763<a href="#damp_level_1d">damp_level_1d</a>)
764is available.</p> </ul> <p><span style="font-style: italic;">'by_user'</span></p><p style="margin-left: 40px;">The initialization of the arrays
765of the 3d-model is under complete control of the user and has to be
766done in routine <a href="chapter_3.5.1.html#user_init_3d_model">user_init_3d_model</a>
767of the user-interface.<span style="font-style: italic;"></span></p><p><span style="font-style: italic;">'initialize_vortex'</span>
768</p> <div style="margin-left: 40px;">The initial
769velocity field of the
7703d-model corresponds to a
771Rankine-vortex with vertical axis. This setting may be used to test
772advection 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>)
773are necessary. In order not to distort the vortex, an initial
774horizontal wind profile constant
775with height is necessary (to be set by <b>initializing_actions</b>
776= <span style="font-style: italic;">'set_constant_profiles'</span>)
777and some other conditions have to be met (neutral stratification,
778diffusion must be
779switched off, see <a href="#km_constant">km_constant</a>).
780The center of the vortex is located at jc = (nx+1)/2. It
781extends from k = 0 to k = nz+1. Its radius is 8 * <a href="#dx">dx</a>
782and the exponentially decaying part ranges to 32 * <a href="#dx">dx</a>
783(see init_rankine.f90). </div> <p><span style="font-style: italic;">'initialize_ptanom'</span>
784</p> <ul> <p>A 2d-Gauss-like shape disturbance
785(x,y) is added to the
786initial temperature field with radius 10.0 * <a href="#dx">dx</a>
787and center at jc = (nx+1)/2. This may be used for tests of scalar
788advection schemes
789(see <a href="#scalar_advec">scalar_advec</a>).
790Such tests require a horizontal wind profile constant with hight and
791diffusion
792switched off (see <span style="font-style: italic;">'initialize_vortex'</span>).
793Additionally, the buoyancy term
794must be switched of in the equation of motion&nbsp; for w (this
795requires the user to comment out the call of <span style="font-family: monospace;">buoyancy</span> in the
796source code of <span style="font-family: monospace;">prognostic_equations.f90</span>).</p>
797</ul> <p style="font-style: normal;">Values may be
798combined, e.g. <b>initializing_actions</b> = <span style="font-style: italic;">'set_constant_profiles
799initialize_vortex'</span>, but the values of <span style="font-style: italic;">'set_constant_profiles'</span>,
800<span style="font-style: italic;">'set_1d-model_profiles'</span>
801, and <span style="font-style: italic;">'by_user'</span>
802must not be given at the same time.</p> <p style="font-style: italic;"> </p> </td> </tr>
803<tr> <td style="vertical-align: top;"> <p><a name="km_constant"></a><b>km_constant</b></p>
804</td> <td style="vertical-align: top;">R</td>
805<td style="vertical-align: top;"><i>variable<br>
806(computed from TKE)</i></td> <td style="vertical-align: top;"> <p>Constant eddy
807diffusivities are used (laminar
808simulations).&nbsp; </p> <p>If this parameter is
809specified, both in the 1d and in the
8103d-model constant values for the eddy diffusivities are used in
811space and time with K<sub>m</sub> = <b>km_constant</b>
812and K<sub>h</sub> = K<sub>m</sub> / <a href="chapter_4.2.html#prandtl_number">prandtl_number</a>.
813The prognostic equation for the subgrid-scale TKE is switched off.
814Constant eddy diffusivities are only allowed with the Prandtl layer (<a href="#prandtl_layer">prandtl_layer</a>)
815switched off.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="km_damp_max"></a><b>km_damp_max</b></p>
816</td> <td style="vertical-align: top;">R</td>
817<td style="vertical-align: top;"><span style="font-style: italic;">0.5*(dx
818or dy)</span></td> <td style="vertical-align: top;">Maximum
819diffusivity used for filtering the velocity field in the vicinity of
820the outflow (in m<sup>2</sup>/s).<br> <br>
821When using non-cyclic lateral boundaries (see <a href="#bc_lr">bc_lr</a>
822or <a href="#bc_ns">bc_ns</a>),
823a smoothing has to be applied to the
824velocity field in the vicinity of the outflow in order to suppress any
825reflections of outgoing disturbances. Smoothing is done by increasing
826the eddy diffusivity along the horizontal direction which is
827perpendicular to the outflow boundary. Only velocity components
828parallel to the outflow boundary are filtered (e.g. v and w, if the
829outflow is along x). Damping is applied from the bottom to the top of
830the domain.<br> <br>
831The horizontal range of the smoothing is controlled by <a href="#outflow_damping_width">outflow_damping_width</a>
832which defines the number of gridpoints (counted from the outflow
833boundary) from where on the smoothing is applied. Starting from that
834point, the eddy diffusivity is linearly increased (from zero to its
835maximum value given by <span style="font-weight: bold;">km_damp_max</span>)
836until half of the damping range width, from where it remains constant
837up to the outflow boundary. If at a certain grid point the eddy
838diffusivity calculated from the flow field is larger than as described
839above, it is used instead.<br> <br>
840The default value of <span style="font-weight: bold;">km_damp_max</span>
841has been empirically proven to be sufficient.</td> </tr> <tr>
842<td style="vertical-align: top;"> <p><a name="long_filter_factor"></a><b>long_filter_factor</b></p>
843</td> <td style="vertical-align: top;">R</td>
844<td style="vertical-align: top;"><i>0.0</i></td>
845<td style="vertical-align: top;"> <p>Filter factor
846for the so-called Long-filter.<br> </p> <p><br>
847This filter very efficiently
848eliminates 2-delta-waves sometimes cauesed by the upstream-spline
849scheme (see Mahrer and
850Pielke, 1978: Mon. Wea. Rev., 106, 818-830). It works in all three
851directions in space. A value of <b>long_filter_factor</b>
852= <i>0.01</i>
853sufficiently removes the small-scale waves without affecting the
854longer waves.<br> </p> <p>By default, the filter is
855switched off (= <i>0.0</i>).
856It is exclusively applied to the tendencies calculated by the
857upstream-spline scheme (see <a href="#momentum_advec">momentum_advec</a>
858and <a href="#scalar_advec">scalar_advec</a>),
859not to the prognostic variables themselves. At the bottom and top
860boundary of the model domain the filter effect for vertical
8612-delta-waves is reduced. There, the amplitude of these waves is only
862reduced by approx. 50%, otherwise by nearly 100%.&nbsp; <br>
863Filter factors with values &gt; <i>0.01</i> also
864reduce the amplitudes
865of waves with wavelengths longer than 2-delta (see the paper by Mahrer
866and
867Pielke, 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
868default, the optimization method depends on the host on which PALM is
869running. On machines with vector-type CPUs, single 3d-loops are used to
870calculate each tendency term of each prognostic equation, while on all
871other machines, all prognostic equations are solved within one big loop
872over 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>
873<td style="vertical-align: top;"><a name="mixing_length_1d"></a><span style="font-weight: bold;">mixing_length_1d</span><br>
874</td> <td style="vertical-align: top;">C*20<br>
875</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>
876<td style="vertical-align: top;">Mixing length used in the
8771d-model.<br> <br>
878By default the mixing length is calculated as in the 3d-model (i.e. it
879depends on the grid spacing).<br> <br>
880By setting <span style="font-weight: bold;">mixing_length_1d</span>
881= <span style="font-style: italic;">'blackadar'</span>,
882the so-called Blackadar mixing length is used (l = kappa * z / ( 1 +
883kappa * z / lambda ) with the limiting value lambda = 2.7E-4 * u_g / f).<br>
884</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="humidity"></a><b>humidity</b></p>
885</td> <td style="vertical-align: top;">L</td>
886<td style="vertical-align: top;"><i>.F.</i></td>
887<td style="vertical-align: top;"> <p>Parameter to
888switch on the prognostic equation for specific
889humidity q.<br> </p> <p>The initial vertical
890profile 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>
891and <a href="chapter_4.1.html#q_vertical_gradient_level">q_vertical_gradient_level</a>.&nbsp;
892Boundary conditions can be set via <a href="chapter_4.1.html#q_surface_initial_change">q_surface_initial_change</a>
893and <a href="chapter_4.1.html#surface_waterflux">surface_waterflux</a>.<br>
894</p>
895If the condensation scheme is switched on (<a href="chapter_4.1.html#cloud_physics">cloud_physics</a>
896= .TRUE.), q becomes the total liquid water content (sum of specific
897humidity and liquid water content).</td> </tr>
898<tr> <td style="vertical-align: top;"> <p><a name="momentum_advec"></a><b>momentum_advec</b></p>
899</td> <td style="vertical-align: top;">C * 10</td>
900<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
901<td style="vertical-align: top;"> <p>Advection
902scheme to be used for the momentum equations.<br> <br>
903The user can choose between the following schemes:<br>
904&nbsp;<br> <br> <span style="font-style: italic;">'pw-scheme'</span><br>
905</p> <div style="margin-left: 40px;">The scheme of
906Piascek and
907Williams (1970, J. Comp. Phys., 6,
908392-405) with central differences in the form C3 is used.<br>
909If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
910= <span style="font-style: italic;">'leapfrog+euler'</span>
911the
912advection scheme is - for the Euler-timestep - automatically switched
913to an upstream-scheme.<br> </div> <p> </p> <p><span style="font-style: italic;">'ups-scheme'</span><br>
914</p> <div style="margin-left: 40px;">The
915upstream-spline scheme is
916used
917(see Mahrer and Pielke,
9181978: Mon. Wea. Rev., 106, 818-830). In opposite to the
919Piascek-Williams scheme, this is characterized by much better numerical
920features (less numerical diffusion, better preservation of flow
921structures, e.g. vortices), but computationally it is much more
922expensive. In
923addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
924= <span style="font-style: italic;">'</span><i>euler'</i>),
925i.e. the
926timestep accuracy is only of first order.
927For this reason the advection of scalar variables (see <a href="#scalar_advec">scalar_advec</a>)
928should then also be carried out with the upstream-spline scheme,
929because otherwise the scalar variables would
930be subject to large numerical diffusion due to the upstream
931scheme.&nbsp; </div> <p style="margin-left: 40px;">Since
932the cubic splines used tend
933to overshoot under
934certain circumstances, this effect must be adjusted by suitable
935filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
936<a href="#long_filter_factor">long_filter_factor</a>,
937<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>).
938This is always neccessary for runs with stable stratification,
939even if this stratification appears only in parts of the model domain.<br>
940</p> <div style="margin-left: 40px;">With stable
941stratification the
942upstream-spline scheme also
943produces gravity waves with large amplitude, which must be
944suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
945<br> <span style="font-weight: bold;">Important: </span>The&nbsp;
946upstream-spline scheme is not implemented for humidity and passive
947scalars (see&nbsp;<a href="#humidity">humidity</a>
948and <a href="#passive_scalar">passive_scalar</a>)
949and requires the use of a 2d-domain-decomposition. The last conditions
950severely restricts code optimization on several machines leading to
951very long execution times! The scheme is also not allowed for
952non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
953and <a href="#bc_ns">bc_ns</a>).</div> </td>
954</tr> <tr> <td style="vertical-align: top;"><a name="netcdf_precision"></a><span style="font-weight: bold;">netcdf_precision</span><br>
955</td> <td style="vertical-align: top;">C*20<br>
956(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>
957<td style="vertical-align: top;">Defines the accuracy of
958the NetCDF output.<br> <br>
959By default, all NetCDF output data (see <a href="chapter_4.2.html#data_output_format">data_output_format</a>)
960have single precision&nbsp; (4 byte) accuracy. Double precision (8
961byte) can be choosen alternatively.<br>
962Accuracy for the different output data (cross sections, 3d-volume data,
963spectra, etc.) can be set independently.<br> <span style="font-style: italic;">'&lt;out&gt;_NF90_REAL4'</span>
964(single precision) or <span style="font-style: italic;">'&lt;out&gt;_NF90_REAL8'</span>
965(double precision) are the two principally allowed values for <span style="font-weight: bold;">netcdf_precision</span>,
966where the string <span style="font-style: italic;">'&lt;out&gt;'
967</span>can be chosen out of the following list:<br> <br>
968<table style="text-align: left; width: 284px; height: 234px;" border="1" cellpadding="2" cellspacing="2"> <tbody>
969<tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xy'</span><br> </td>
970<td style="vertical-align: top;">horizontal cross section<br>
971</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'xz'</span><br> </td>
972<td style="vertical-align: top;">vertical (xz) cross
973section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'yz'</span><br> </td>
974<td style="vertical-align: top;">vertical (yz) cross
975section<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'2d'</span><br> </td>
976<td style="vertical-align: top;">all cross sections<br>
977</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'3d'</span><br> </td>
978<td style="vertical-align: top;">volume data<br> </td>
979</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'pr'</span><br> </td>
980<td style="vertical-align: top;">vertical profiles<br>
981</td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'ts'</span><br> </td>
982<td style="vertical-align: top;">time series, particle
983time series<br> </td> </tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'sp'</span><br> </td>
984<td style="vertical-align: top;">spectra<br> </td>
985</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'prt'</span><br> </td>
986<td style="vertical-align: top;">particles<br> </td>
987</tr> <tr> <td style="vertical-align: top;"><span style="font-style: italic;">'all'</span><br> </td>
988<td style="vertical-align: top;">all output quantities<br>
989</td> </tr> </tbody> </table> <br> <span style="font-weight: bold;">Example:</span><br>
990If all cross section data and the particle data shall be output in
991double 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>
992has to be assigned.<br> </td> </tr>
993<tr> <td style="vertical-align: top;"> <p><a name="npex"></a><b>npex</b></p> </td>
994<td style="vertical-align: top;">I</td> <td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
995along x-direction of the virtual
996processor
997net.&nbsp; </p> <p>For parallel runs, the total
998number of processors to be used
999is given by
1000the <span style="font-weight: bold;">mrun</span>
1001option <a href="http://www.muk.uni-hannover.de/software/mrun_beschreibung.html#Opt-X">-X</a>.
1002By default, depending on the type of the parallel computer, PALM
1003generates a 1d processor
1004net (domain decomposition along x, <span style="font-weight: bold;">npey</span>
1005= <span style="font-style: italic;">1</span>) or a
10062d-net (this is
1007favored on machines with fast communication network). In case of a
10082d-net, it is tried to make it more or less square-shaped. If, for
1009example, 16 processors are assigned (-X 16), a 4 * 4 processor net is
1010generated (<span style="font-weight: bold;">npex</span>
1011= <span style="font-style: italic;">4</span>, <span style="font-weight: bold;">npey</span>
1012= <span style="font-style: italic;">4</span>).
1013This choice is optimal for square total domains (<a href="#nx">nx</a>
1014= <a href="#ny">ny</a>),
1015since then the number of ghost points at the lateral boundarys of
1016the subdomains is minimal. If <span style="font-weight: bold;">nx</span>
1017nd <span style="font-weight: bold;">ny</span>
1018differ extremely, the
1019processor 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>
1020<p><b>Important:</b> The value of <span style="font-weight: bold;">npex</span> * <span style="font-weight: bold;">npey</span> must exactly
1021correspond to the
1022value assigned by the <span style="font-weight: bold;">mrun</span>-option
1023<tt>-X</tt>.
1024Otherwise the model run will abort with a corresponding error
1025message.&nbsp; <br>
1026Additionally, the specification of <span style="font-weight: bold;">npex</span>
1027and <span style="font-weight: bold;">npey</span>
1028may of course
1029override the default setting for the domain decomposition (1d or 2d)
1030which may have a significant (negative) effect on the code performance.
1031</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="npey"></a><b>npey</b></p>
1032</td> <td style="vertical-align: top;">I</td>
1033<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of processors
1034along y-direction of the virtual
1035processor
1036net.&nbsp; </p> <p>For further information see <a href="#npex">npex</a>.</p> </td> </tr>
1037<tr> <td style="vertical-align: top;"> <p><a name="nsor_ini"></a><b>nsor_ini</b></p>
1038</td> <td style="vertical-align: top;">I</td>
1039<td style="vertical-align: top;"><i>100</i></td>
1040<td style="vertical-align: top;"> <p>Initial number
1041of iterations with the SOR algorithm.&nbsp; </p> <p>This
1042parameter is only effective if the SOR algorithm was
1043selected as the pressure solver scheme (<a href="chapter_4.2.html#psolver">psolver</a>
1044= <span style="font-style: italic;">'sor'</span>)
1045and specifies the
1046number of initial iterations of the SOR
1047scheme (at t = 0). The number of subsequent iterations at the following
1048timesteps is determined
1049with the parameter <a href="#nsor">nsor</a>.
1050Usually <b>nsor</b> &lt; <b>nsor_ini</b>,
1051since in each case
1052subsequent calls to <a href="chapter_4.2.html#psolver">psolver</a>
1053use the solution of the previous call as initial value. Suitable
1054test runs should determine whether sufficient convergence of the
1055solution is obtained with the default value and if necessary the value
1056of <b>nsor_ini</b> should be changed.</p> </td>
1057</tr> <tr> <td style="vertical-align: top;">
1058<p><a name="nx"></a><b>nx</b></p>
1059</td> <td style="vertical-align: top;">I</td>
1060<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1061points in x-direction.&nbsp; </p> <p>A value for this
1062parameter must be assigned. Since the lower
1063array bound in PALM
1064starts with i = 0, the actual number of grid points is equal to <b>nx+1</b>.
1065In case of cyclic boundary conditions along x, the domain size is (<b>nx+1</b>)*
1066<a href="#dx">dx</a>.</p> <p>For
1067parallel runs, in case of <a href="#grid_matching">grid_matching</a>
1068= <span style="font-style: italic;">'strict'</span>,
1069<b>nx+1</b> must
1070be an integral multiple
1071of the processor numbers (see <a href="#npex">npex</a>
1072and <a href="#npey">npey</a>)
1073along x- as well as along y-direction (due to data
1074transposition restrictions).</p> </td> </tr> <tr>
1075<td style="vertical-align: top;"> <p><a name="ny"></a><b>ny</b></p>
1076</td> <td style="vertical-align: top;">I</td>
1077<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1078points in y-direction.&nbsp; </p> <p>A value for this
1079parameter must be assigned. Since the lower
1080array bound in PALM starts with i = 0, the actual number of grid points
1081is equal to <b>ny+1</b>. In case of cyclic boundary
1082conditions along
1083y, the domain size is (<b>ny+1</b>) * <a href="#dy">dy</a>.</p>
1084<p>For parallel runs, in case of <a href="#grid_matching">grid_matching</a>
1085= <span style="font-style: italic;">'strict'</span>,
1086<b>ny+1</b> must
1087be an integral multiple
1088of the processor numbers (see <a href="#npex">npex</a>
1089and <a href="#npey">npey</a>)&nbsp;
1090along y- as well as along x-direction (due to data
1091transposition restrictions).</p> </td> </tr> <tr>
1092<td style="vertical-align: top;"> <p><a name="nz"></a><b>nz</b></p>
1093</td> <td style="vertical-align: top;">I</td>
1094<td style="vertical-align: top;"><br> </td> <td style="vertical-align: top;"> <p>Number of grid
1095points in z-direction.&nbsp; </p> <p>A value for this
1096parameter must be assigned. Since the lower
1097array bound in PALM
1098starts with k = 0 and since one additional grid point is added at the
1099top boundary (k = <b>nz+1</b>), the actual number of grid
1100points is <b>nz+2</b>.
1101However, the prognostic equations are only solved up to <b>nz</b>
1102(u,
1103v)
1104or up to <b>nz-1</b> (w, scalar quantities). The top
1105boundary for u
1106and v is at k = <b>nz+1</b> (u, v) while at k = <b>nz</b>
1107for all
1108other quantities.&nbsp; </p> <p>For parallel
1109runs,&nbsp; in case of <a href="#grid_matching">grid_matching</a>
1110= <span style="font-style: italic;">'strict'</span>,
1111<b>nz</b> must
1112be an integral multiple of
1113the number of processors in x-direction (due to data transposition
1114restrictions).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="omega"></a><b>omega</b></p>
1115</td> <td style="vertical-align: top;">R</td>
1116<td style="vertical-align: top;"><i>7.29212E-5</i></td>
1117<td style="vertical-align: top;"> <p>Angular
1118velocity of the rotating system (in rad s<sup>-1</sup>).&nbsp;
1119</p> <p>The angular velocity of the earth is set by
1120default. The
1121values
1122of the Coriolis parameters are calculated as:&nbsp; </p> <ul>
1123<p>f = 2.0 * <b>omega</b> * sin(<a href="#phi">phi</a>)&nbsp;
1124<br>f* = 2.0 * <b>omega</b> * cos(<a href="#phi">phi</a>)</p>
1125</ul> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="outflow_damping_width"></a><b>outflow_damping_width</b></p>
1126</td> <td style="vertical-align: top;">I</td>
1127<td style="vertical-align: top;"><span style="font-style: italic;">MIN(20,
1128nx/2</span> or <span style="font-style: italic;">ny/2)</span></td>
1129<td style="vertical-align: top;">Width of
1130the damping range in the vicinity of the outflow (gridpoints).<br>
1131<br>
1132When using non-cyclic lateral boundaries (see <a href="chapter_4.1.html#bc_lr">bc_lr</a>
1133or <a href="chapter_4.1.html#bc_ns">bc_ns</a>),
1134a smoothing has to be applied to the
1135velocity field in the vicinity of the outflow in order to suppress any
1136reflections of outgoing disturbances. This parameter controlls the
1137horizontal range to which the smoothing is applied. The range is given
1138in gridpoints counted from the respective outflow boundary. For further
1139details about the smoothing see parameter <a href="chapter_4.1.html#km_damp_max">km_damp_max</a>,
1140which defines the magnitude of the damping.</td> </tr>
1141<tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_e"></a><b>overshoot_limit_e</b></p>
1142</td> <td style="vertical-align: top;">R</td>
1143<td style="vertical-align: top;"><i>0.0</i></td>
1144<td style="vertical-align: top;"> <p>Allowed limit
1145for the overshooting of subgrid-scale TKE in
1146case that the upstream-spline scheme is switched on (in m<sup>2</sup>/s<sup>2</sup>).&nbsp;
1147</p> <p>By deafult, if cut-off of overshoots is switched
1148on for the
1149upstream-spline scheme (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>),
1150no overshoots are permitted at all. If <b>overshoot_limit_e</b>
1151is given a non-zero value, overshoots with the respective
1152amplitude (both upward and downward) are allowed.&nbsp; </p>
1153<p>Only positive values are allowed for <b>overshoot_limit_e</b>.</p>
1154</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_pt"></a><b>overshoot_limit_pt</b></p>
1155</td> <td style="vertical-align: top;">R</td>
1156<td style="vertical-align: top;"><i>0.0</i></td>
1157<td style="vertical-align: top;"> <p>Allowed limit
1158for the overshooting of potential temperature in
1159case that the upstream-spline scheme is switched on (in K).&nbsp; </p>
1160<p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1161</p> <p>Only positive values are allowed for <b>overshoot_limit_pt</b>.</p>
1162</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_u"></a><b>overshoot_limit_u</b></p>
1163</td> <td style="vertical-align: top;">R</td>
1164<td style="vertical-align: top;"><i>0.0</i></td>
1165<td style="vertical-align: top;">Allowed limit for the
1166overshooting of
1167the u-component of velocity in case that the upstream-spline scheme is
1168switched on (in m/s). <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1169</p> <p>Only positive values are allowed for <b>overshoot_limit_u</b>.</p>
1170</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_v"></a><b>overshoot_limit_v</b></p>
1171</td> <td style="vertical-align: top;">R</td>
1172<td style="vertical-align: top;"><i>0.0</i></td>
1173<td style="vertical-align: top;"> <p>Allowed limit
1174for the overshooting of the v-component of
1175velocity in case that the upstream-spline scheme is switched on
1176(in m/s).&nbsp; </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1177</p> <p>Only positive values are allowed for <b>overshoot_limit_v</b>.</p>
1178</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="overshoot_limit_w"></a><b>overshoot_limit_w</b></p>
1179</td> <td style="vertical-align: top;">R</td>
1180<td style="vertical-align: top;"><i>0.0</i></td>
1181<td style="vertical-align: top;"> <p>Allowed limit
1182for the overshooting of the w-component of
1183velocity in case that the upstream-spline scheme is switched on
1184(in m/s).&nbsp; </p> <p>For further information see <a href="#overshoot_limit_e">overshoot_limit_e</a>.&nbsp;
1185</p> <p>Only positive values are permitted for <b>overshoot_limit_w</b>.</p>
1186</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="passive_scalar"></a><b>passive_scalar</b></p>
1187</td> <td style="vertical-align: top;">L</td>
1188<td style="vertical-align: top;"><i>.F.</i></td>
1189<td style="vertical-align: top;"> <p>Parameter to
1190switch on the prognostic equation for a passive
1191scalar. <br> </p> <p>The initial vertical profile
1192of s can be set via parameters <a href="#s_surface">s_surface</a>,
1193<a href="#s_vertical_gradient">s_vertical_gradient</a>
1194and&nbsp; <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
1195Boundary conditions can be set via <a href="#s_surface_initial_change">s_surface_initial_change</a>
1196and <a href="#surface_scalarflux">surface_scalarflux</a>.&nbsp;
1197</p> <p><b>Note:</b> <br>
1198With <span style="font-weight: bold;">passive_scalar</span>
1199switched
1200on, the simultaneous use of humidity (see&nbsp;<a href="#humidity">humidity</a>)
1201is impossible.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="phi"></a><b>phi</b></p>
1202</td> <td style="vertical-align: top;">R</td>
1203<td style="vertical-align: top;"><i>55.0</i></td>
1204<td style="vertical-align: top;"> <p>Geographical
1205latitude (in degrees).&nbsp; </p> <p>The value of
1206this parameter determines the value of the
1207Coriolis parameters f and f*, provided that the angular velocity (see <a href="#omega">omega</a>)
1208is non-zero.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="prandtl_layer"></a><b>prandtl_layer</b></p>
1209</td> <td style="vertical-align: top;">L</td>
1210<td style="vertical-align: top;"><i>.T.</i></td>
1211<td style="vertical-align: top;"> <p>Parameter to
1212switch on a Prandtl layer.&nbsp; </p> <p>By default,
1213a Prandtl layer is switched on at the bottom
1214boundary between z = 0 and z = 0.5 * <a href="#dz">dz</a>
1215(the first computational grid point above ground for u, v and the
1216scalar quantities).
1217In this case, at the bottom boundary, free-slip conditions for u and v
1218(see <a href="#bc_uv_b">bc_uv_b</a>)
1219are not allowed. Likewise, laminar
1220simulations with constant eddy diffusivities (<a href="#km_constant">km_constant</a>)
1221are forbidden.&nbsp; </p> <p>With Prandtl-layer
1222switched off, the TKE boundary condition <a href="#bc_e_b">bc_e_b</a>
1223= '<i>(u*)**2+neumann'</i> must not be used and is
1224automatically
1225changed to <i>'neumann'</i> if necessary.&nbsp; Also,
1226the pressure
1227boundary condition <a href="#bc_p_b">bc_p_b</a>
1228= <i>'neumann+inhomo'</i>&nbsp; is not allowed. </p>
1229<p>The roughness length is declared via the parameter <a href="#roughness_length">roughness_length</a>.</p>
1230</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="precipitation"></a><b>precipitation</b></p>
1231</td> <td style="vertical-align: top;">L</td>
1232<td style="vertical-align: top;"><span style="font-style: italic;">.F.</span></td> <td style="vertical-align: top;"> <p>Parameter to switch
1233on the precipitation scheme.<br> </p> <p>For
1234precipitation processes PALM uses a simplified Kessler
1235scheme. This scheme only considers the
1236so-called autoconversion, that means the generation of rain water by
1237coagulation of cloud drops among themselves. Precipitation begins and
1238is immediately removed from the flow as soon as the liquid water
1239content 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>
1240<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
1241refrence</span></td><td style="vertical-align: top;">Reference
1242temperature to be used in all buoyancy terms (in K).<br><br>By
1243default, the instantaneous horizontal average over the total model
1244domain is used.</td></tr><tr> <td style="vertical-align: top;"> <p><a name="pt_surface"></a><b>pt_surface</b></p>
1245</td> <td style="vertical-align: top;">R</td>
1246<td style="vertical-align: top;"><i>300.0</i></td>
1247<td style="vertical-align: top;"> <p>Surface
1248potential temperature (in K).&nbsp; </p> <p>This
1249parameter assigns the value of the potential temperature
1250pt at the surface (k=0)<b>.</b> Starting from this value,
1251the
1252initial vertical temperature profile is constructed with <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1253and <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level
1254</a>.
1255This profile is also used for the 1d-model as a stationary profile.</p>
1256</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_surface_initial_change"></a><b>pt_surface_initial</b>
1257<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>
1258<td style="vertical-align: top;"> <p>Change in
1259surface temperature to be made at the beginning of
1260the 3d run
1261(in K).&nbsp; </p> <p>If <b>pt_surface_initial_change</b>
1262is set to a non-zero
1263value, the near surface sensible heat flux is not allowed to be given
1264simultaneously (see <a href="#surface_heatflux">surface_heatflux</a>).</p>
1265</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient"></a><b>pt_vertical_gradient</b></p>
1266</td> <td style="vertical-align: top;">R (10)</td>
1267<td style="vertical-align: top;"><i>10 * 0.0</i></td>
1268<td style="vertical-align: top;"> <p>Temperature
1269gradient(s) of the initial temperature profile (in
1270K
1271/ 100 m).&nbsp; </p> <p>This temperature gradient
1272holds starting from the height&nbsp;
1273level defined by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>
1274(precisely: for all uv levels k where zu(k) &gt;
1275pt_vertical_gradient_level,
1276pt_init(k) is set: pt_init(k) = pt_init(k-1) + dzu(k) * <b>pt_vertical_gradient</b>)
1277up to the top boundary or up to the next height level defined
1278by <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>.
1279A total of 10 different gradients for 11 height intervals (10 intervals
1280if <a href="#pt_vertical_gradient_level">pt_vertical_gradient_level</a>(1)
1281= <i>0.0</i>) can be assigned. The surface temperature is
1282assigned via <a href="#pt_surface">pt_surface</a>.&nbsp;
1283</p> <p>Example:&nbsp; </p> <ul> <p><b>pt_vertical_gradient</b>
1284= <i>1.0</i>, <i>0.5</i>,&nbsp; <br>
1285<b>pt_vertical_gradient_level</b> = <i>500.0</i>,
1286<i>1000.0</i>,</p> </ul> <p>That
1287defines the temperature profile to be neutrally
1288stratified
1289up to z = 500.0 m with a temperature given by <a href="#pt_surface">pt_surface</a>.
1290For 500.0 m &lt; z &lt;= 1000.0 m the temperature gradient is
12911.0 K /
1292100 m and for z &gt; 1000.0 m up to the top boundary it is
12930.5 K / 100 m (it is assumed that the assigned height levels correspond
1294with uv levels). </p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="pt_vertical_gradient_level"></a><b>pt_vertical_gradient</b>
1295<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>&nbsp;
1296<span style="font-style: italic;">0.0</span><br>
1297</p> </td> <td style="vertical-align: top;">
1298<p>Height level from which on the temperature gradient defined by
1299<a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1300is effective (in m).&nbsp; </p> <p>The height levels
1301are to be assigned in ascending order. The
1302default values result in a neutral stratification regardless of the
1303values of <a href="#pt_vertical_gradient">pt_vertical_gradient</a>
1304(unless the top boundary of the model is higher than 100000.0 m).
1305For the piecewise construction of temperature profiles see <a href="#pt_vertical_gradient">pt_vertical_gradient</a>.</p>
1306</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface"></a><b>q_surface</b></p>
1307</td> <td style="vertical-align: top;">R</td>
1308<td style="vertical-align: top;"><i>0.0</i></td>
1309<td style="vertical-align: top;"> <p>Surface
1310specific humidity / total water content (kg/kg).&nbsp; </p> <p>This
1311parameter assigns the value of the specific humidity q at
1312the surface (k=0).&nbsp; Starting from this value, the initial
1313humidity
1314profile is constructed with&nbsp; <a href="#q_vertical_gradient">q_vertical_gradient</a>
1315and <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
1316This profile is also used for the 1d-model as a stationary profile.</p>
1317</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_surface_initial_change"></a><b>q_surface_initial</b>
1318<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R<br> </td> <td style="vertical-align: top;"><i>0.0</i></td>
1319<td style="vertical-align: top;"> <p>Change in
1320surface specific humidity / total water content to
1321be made at the beginning
1322of the 3d run (kg/kg).&nbsp; </p> <p>If <b>q_surface_initial_change</b><i>
1323</i>is set to a
1324non-zero value the
1325near surface latent heat flux (water flux) is not allowed to be given
1326simultaneously (see <a href="#surface_waterflux">surface_waterflux</a>).</p>
1327</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient"></a><b>q_vertical_gradient</b></p>
1328</td> <td style="vertical-align: top;">R (10)</td>
1329<td style="vertical-align: top;"><i>10 * 0.0</i></td>
1330<td style="vertical-align: top;"> <p>Humidity
1331gradient(s) of the initial humidity profile
1332(in 1/100 m).&nbsp; </p> <p>This humidity gradient
1333holds starting from the height
1334level&nbsp; defined by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>
1335(precisely: for all uv levels k, where zu(k) &gt;
1336q_vertical_gradient_level,
1337q_init(k) is set: q_init(k) = q_init(k-1) + dzu(k) * <b>q_vertical_gradient</b>)
1338up to the top boundary or up to the next height level defined
1339by <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>.
1340A total of 10 different gradients for 11 height intervals (10 intervals
1341if <a href="#q_vertical_gradient_level">q_vertical_gradient_level</a>(1)
1342= <i>0.0</i>) can be asigned. The surface humidity is
1343assigned
1344via <a href="#q_surface">q_surface</a>. </p>
1345<p>Example:&nbsp; </p> <ul> <p><b>q_vertical_gradient</b>
1346= <i>0.001</i>, <i>0.0005</i>,&nbsp; <br>
1347<b>q_vertical_gradient_level</b> = <i>500.0</i>,
1348<i>1000.0</i>,</p> </ul>
1349That defines the humidity to be constant with height up to z =
1350500.0
1351m with a
1352value given by <a href="#q_surface">q_surface</a>.
1353For 500.0 m &lt; z &lt;= 1000.0 m the humidity gradient is
13540.001 / 100
1355m and for z &gt; 1000.0 m up to the top boundary it is
13560.0005 / 100 m (it is assumed that the assigned height levels
1357correspond with uv
1358levels). </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="q_vertical_gradient_level"></a><b>q_vertical_gradient</b>
1359<br> <b>_level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>&nbsp;
1360<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
1361which on the humidity gradient defined by <a href="#q_vertical_gradient">q_vertical_gradient</a>
1362is effective (in m).&nbsp; </p> <p>The height levels
1363are to be assigned in ascending order. The
1364default values result in a humidity constant with height regardless of
1365the values of <a href="#q_vertical_gradient">q_vertical_gradient</a>
1366(unless the top boundary of the model is higher than 100000.0 m). For
1367the piecewise construction of humidity profiles see <a href="#q_vertical_gradient">q_vertical_gradient</a>.</p>
1368</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="radiation"></a><b>radiation</b></p>
1369</td> <td style="vertical-align: top;">L</td>
1370<td style="vertical-align: top;"><i>.F.</i></td>
1371<td style="vertical-align: top;"> <p>Parameter to
1372switch on longwave radiation cooling at
1373cloud-tops.&nbsp; </p> <p>Long-wave radiation
1374processes are parameterized by the
1375effective emissivity, which considers only the absorption and emission
1376of long-wave radiation at cloud droplets. The radiation scheme can be
1377used only with <a href="#cloud_physics">cloud_physics</a>
1378= .TRUE. .</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="random_generator"></a><b>random_generator</b></p>
1379</td> <td style="vertical-align: top;">C * 20</td>
1380<td style="vertical-align: top;"> <p><i>'numerical</i><br>
1381<i>recipes'</i></p> </td> <td style="vertical-align: top;"> <p>Random number
1382generator to be used for creating uniformly
1383distributed random numbers. <br> </p> <p>It is
1384used if random perturbations are to be imposed on the
1385velocity field or on the surface heat flux field (see <a href="chapter_4.2.html#create_disturbances">create_disturbances</a>
1386and <a href="chapter_4.2.html#random_heatflux">random_heatflux</a>).
1387By default, the "Numerical Recipes" random number generator is used.
1388This one provides exactly the same order of random numbers on all
1389different machines and should be used in particular for comparison runs.<br>
1390<br>
1391Besides, a system-specific generator is available ( <b>random_generator</b>
1392= <i>'system-specific')</i> which should particularly be
1393used for runs
1394on vector parallel computers (NEC), because the default generator
1395cannot be vectorized and therefore significantly drops down the code
1396performance on these machines.<br> </p> <span style="font-weight: bold;">Note:</span><br>
1397Results from two otherwise identical model runs will not be comparable
1398one-to-one if they used different random number generators.</td> </tr>
1399<tr> <td style="vertical-align: top;"> <p><a name="random_heatflux"></a><b>random_heatflux</b></p>
1400</td> <td style="vertical-align: top;">L</td>
1401<td style="vertical-align: top;"><i>.F.</i></td>
1402<td style="vertical-align: top;"> <p>Parameter to
1403impose random perturbations on the internal two-dimensional near
1404surface heat flux field <span style="font-style: italic;">shf</span>.
1405<br> </p>If a near surface heat flux is used as bottom
1406boundary
1407condition (see <a href="#surface_heatflux">surface_heatflux</a>),
1408it is by default assumed to be horizontally homogeneous. Random
1409perturbations can be imposed on the internal
1410two-dimensional&nbsp;heat flux field <span style="font-style: italic;">shf</span> by assigning <b>random_heatflux</b>
1411= <i>.T.</i>. The disturbed heat flux field is calculated
1412by
1413multiplying the
1414values at each mesh point with a normally distributed random number
1415with a mean value and standard deviation of 1. This is repeated after
1416every timestep.<br> <br>
1417In case of a non-flat <a href="#topography">topography</a>,&nbsp;assigning
1418<b>random_heatflux</b>
1419= <i>.T.</i> imposes random perturbations on the
1420combined&nbsp;heat
1421flux field <span style="font-style: italic;">shf</span>
1422composed of <a href="#surface_heatflux">surface_heatflux</a>
1423at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
1424at the topography top face.</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_max"></a><b>rif_max</b></p>
1425</td> <td style="vertical-align: top;">R</td>
1426<td style="vertical-align: top;"><i>1.0</i></td>
1427<td style="vertical-align: top;"> <p>Upper limit of
1428the flux-Richardson number.&nbsp; </p> <p>With the
1429Prandtl layer switched on (see <a href="#prandtl_layer">prandtl_layer</a>),
1430flux-Richardson numbers (rif) are calculated for z=z<sub>p</sub>
1431(k=1)
1432in the 3d-model (in the 1d model for all heights). Their values in
1433particular determine the
1434values of the friction velocity (1d- and 3d-model) and the values of
1435the eddy diffusivity (1d-model). With small wind velocities at the
1436Prandtl layer top or small vertical wind shears in the 1d-model, rif
1437can take up unrealistic large values. They are limited by an upper (<span style="font-weight: bold;">rif_max</span>) and lower
1438limit (see <a href="#rif_min">rif_min</a>)
1439for the flux-Richardson number. The condition <b>rif_max</b>
1440&gt; <b>rif_min</b>
1441must be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="rif_min"></a><b>rif_min</b></p>
1442</td> <td style="vertical-align: top;">R</td>
1443<td style="vertical-align: top;"><i>- 5.0</i></td>
1444<td style="vertical-align: top;"> <p>Lower limit of
1445the flux-Richardson number.&nbsp; </p> <p>For further
1446explanations see <a href="#rif_max">rif_max</a>.
1447The condition <b>rif_max</b> &gt; <b>rif_min </b>must
1448be met.</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="roughness_length"></a><b>roughness_length</b></p>
1449</td> <td style="vertical-align: top;">R</td>
1450<td style="vertical-align: top;"><i>0.1</i></td>
1451<td style="vertical-align: top;"> <p>Roughness
1452length (in m).&nbsp; </p> <p>This parameter is
1453effective only in case that a Prandtl layer
1454is switched
1455on (see <a href="#prandtl_layer">prandtl_layer</a>).</p>
1456</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="scalar_advec"></a><b>scalar_advec</b></p>
1457</td> <td style="vertical-align: top;">C * 10</td>
1458<td style="vertical-align: top;"><i>'pw-scheme'</i></td>
1459<td style="vertical-align: top;"> <p>Advection
1460scheme to be used for the scalar quantities.&nbsp; </p> <p>The
1461user can choose between the following schemes:<br> </p> <p><span style="font-style: italic;">'pw-scheme'</span><br>
1462</p> <div style="margin-left: 40px;">The scheme of
1463Piascek and
1464Williams (1970, J. Comp. Phys., 6,
1465392-405) with central differences in the form C3 is used.<br>
1466If intermediate Euler-timesteps are carried out in case of <a href="#timestep_scheme">timestep_scheme</a>
1467= <span style="font-style: italic;">'leapfrog+euler'</span>
1468the
1469advection scheme is - for the Euler-timestep - automatically switched
1470to an upstream-scheme. <br> </div> <br> <p><span style="font-style: italic;">'bc-scheme'</span><br>
1471</p> <div style="margin-left: 40px;">The Bott
1472scheme modified by
1473Chlond (1994, Mon.
1474Wea. Rev., 122, 111-125). This is a conservative monotonous scheme with
1475very small numerical diffusion and therefore very good conservation of
1476scalar flow features. The scheme however, is computationally very
1477expensive both because it is expensive itself and because it does (so
1478far) not allow specific code optimizations (e.g. cache optimization).
1479Choice of this
1480scheme forces the Euler timestep scheme to be used for the scalar
1481quantities. For output of horizontally averaged
1482profiles of the resolved / total heat flux, <a href="chapter_4.2.html#data_output_pr">data_output_pr</a>
1483= <i>'w*pt*BC'</i> / <i>'wptBC' </i>should
1484be used, instead of the
1485standard profiles (<span style="font-style: italic;">'w*pt*'</span>
1486and <span style="font-style: italic;">'wpt'</span>)
1487because these are
1488too inaccurate with this scheme. However, for subdomain analysis (see <a href="#statistic_regions">statistic_regions</a>)
1489exactly the reverse holds: here <i>'w*pt*BC'</i> and <i>'wptBC'</i>
1490show very large errors and should not be used.<br> <br>
1491This scheme is not allowed for non-cyclic lateral boundary conditions
1492(see <a href="#bc_lr">bc_lr</a>
1493and <a href="#bc_ns">bc_ns</a>).<br> <br>
1494</div> <span style="font-style: italic;">'ups-scheme'</span><br>
1495<p style="margin-left: 40px;">The upstream-spline-scheme
1496is used
1497(see Mahrer and Pielke,
14981978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piascek
1499Williams scheme, this is characterized by much better numerical
1500features (less numerical diffusion, better preservation of flux
1501structures, e.g. vortices), but computationally it is much more
1502expensive. In
1503addition, the use of the Euler-timestep scheme is mandatory (<a href="#timestep_scheme">timestep_scheme</a>
1504= <span style="font-style: italic;">'</span><i>euler'</i>),
1505i.e. the
1506timestep accuracy is only first order. For this reason the advection of
1507momentum (see <a href="#momentum_advec">momentum_advec</a>)
1508should then also be carried out with the upstream-spline scheme,
1509because otherwise the momentum would
1510be subject to large numerical diffusion due to the upstream
1511scheme.&nbsp; </p> <p style="margin-left: 40px;">Since
1512the cubic splines used tend
1513to overshoot under
1514certain circumstances, this effect must be adjusted by suitable
1515filtering and smoothing (see <a href="#cut_spline_overshoot">cut_spline_overshoot</a>,
1516<a href="#long_filter_factor">long_filter_factor</a>,
1517<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>).
1518This is always neccesssary for runs with stable stratification,
1519even if this stratification appears only in parts of the model
1520domain.&nbsp; </p> <p style="margin-left: 40px;">With
1521stable stratification the
1522upstream-upline scheme also produces gravity waves with large
1523amplitude, which must be
1524suitably damped (see <a href="chapter_4.2.html#rayleigh_damping_factor">rayleigh_damping_factor</a>).<br>
1525</p> <p style="margin-left: 40px;"><span style="font-weight: bold;">Important: </span>The&nbsp;
1526upstream-spline scheme is not implemented for humidity and passive
1527scalars (see&nbsp;<a href="#humidity">humidity</a>
1528and <a href="#passive_scalar">passive_scalar</a>)
1529and requires the use of a 2d-domain-decomposition. The last conditions
1530severely restricts code optimization on several machines leading to
1531very long execution times! This scheme is also not allowed for
1532non-cyclic lateral boundary conditions (see <a href="#bc_lr">bc_lr</a>
1533and <a href="#bc_ns">bc_ns</a>).</p><br>A
1534differing advection scheme can be choosed for the subgrid-scale TKE
1535using parameter <a href="chapter_4.1.html#use_upstream_for_tke">use_upstream_for_tke</a>.</td>
1536</tr> <tr> <td style="vertical-align: top;">
1537<p><a name="statistic_regions"></a><b>statistic_regions</b></p>
1538</td> <td style="vertical-align: top;">I</td>
1539<td style="vertical-align: top;"><i>0</i></td>
1540<td style="vertical-align: top;"> <p>Number of
1541additional user-defined subdomains for which
1542statistical analysis
1543and corresponding output (profiles, time series) shall be
1544made.&nbsp; </p> <p>By default, vertical profiles and
1545other statistical quantities
1546are calculated as horizontal and/or volume average of the total model
1547domain. Beyond that, these calculations can also be carried out for
1548subdomains which can be defined using the field <a href="chapter_3.5.3.html">rmask </a>within the
1549user-defined software
1550(see <a href="chapter_3.5.3.html">chapter
15513.5.3</a>). The number of these subdomains is determined with the
1552parameter <b>statistic_regions</b>. Maximum 9 additional
1553subdomains
1554are allowed. The parameter <a href="chapter_4.3.html#region">region</a>
1555can be used to assigned names (identifier) to these subdomains which
1556are then used in the headers
1557of the output files and plots.</p><p>If the default NetCDF
1558output format is selected (see parameter <a href="chapter_4.2.html#data_output_format">data_output_format</a>),
1559data for the total domain and all defined subdomains are output to the
1560same file(s) (<a href="chapter_3.4.html#DATA_1D_PR_NETCDF">DATA_1D_PR_NETCDF</a>,
1561<a href="chapter_3.4.html#DATA_1D_TS_NETCDF">DATA_1D_TS_NETCDF</a>).
1562In case of <span style="font-weight: bold;">statistic_regions</span>
1563&gt; <span style="font-style: italic;">0</span>,
1564data on the file for the different domains can be distinguished by a
1565suffix which is appended to the quantity names. Suffix 0 means data for
1566the total domain, suffix 1 means data for subdomain 1, etc.</p><p>In
1567case of <span style="font-weight: bold;">data_output_format</span>
1568= <span style="font-style: italic;">'profil'</span>,
1569individual local files for profiles (<a href="chapter_3.4.html#PLOT1D_DATA">PLOT1D_DATA</a>)&nbsp;are
1570created for each subdomain. The individual subdomain files differ by
1571their name (the
1572number of the respective subdomain is attached, e.g.
1573PLOT1D_DATA_1). In this case the name of the file with the data of
1574the total domain is PLOT1D_DATA_0. If no subdomains
1575are declared (<b>statistic_regions</b> = <i>0</i>),
1576the name
1577PLOT1D_DATA is used (this must be considered in the
1578respective file connection statements of the <span style="font-weight: bold;">mrun</span> configuration
1579file).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_heatflux"></a><b>surface_heatflux</b></p>
1580</td> <td style="vertical-align: top;">R</td>
1581<td style="vertical-align: top;"><span style="font-style: italic;">no prescribed<br>
1582heatflux<br> </span></td> <td style="vertical-align: top;"> <p>Kinematic sensible
1583heat flux at the bottom surface (in K m/s).&nbsp; </p> <p>If
1584a value is assigned to this parameter, the internal two-dimensional
1585surface heat flux field <span style="font-style: italic;">shf</span>
1586is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span>&nbsp;as
1587bottom (horizontally homogeneous) boundary condition for the
1588temperature equation. This additionally requires that a Neumann
1589condition must be used for the potential temperature (see <a href="#bc_pt_b">bc_pt_b</a>),
1590because otherwise the resolved scale may contribute to
1591the surface flux so that a constant value cannot be guaranteed. Also,
1592changes of the
1593surface temperature (see <a href="#pt_surface_initial_change">pt_surface_initial_change</a>)
1594are not allowed. The parameter <a href="#random_heatflux">random_heatflux</a>
1595can be used to impose random perturbations on the (homogeneous) surface
1596heat
1597flux field <span style="font-style: italic;">shf</span>.&nbsp;</p>
1598<p>
1599In case of a non-flat <a href="#topography">topography</a>,&nbsp;the
1600internal two-dimensional&nbsp;surface heat
1601flux field <span style="font-style: italic;">shf</span>
1602is initialized with the value of <span style="font-weight: bold;">surface_heatflux</span>
1603at the bottom surface and <a href="#wall_heatflux">wall_heatflux(0)</a>
1604at the topography top face.&nbsp;The parameter<a href="#random_heatflux"> random_heatflux</a>
1605can be used to impose random perturbations on this combined surface
1606heat
1607flux field <span style="font-style: italic;">shf</span>.&nbsp;
1608</p> <p>If no surface heat flux is assigned, <span style="font-style: italic;">shf</span> is calculated
1609at each timestep by u<sub>*</sub> * theta<sub>*</sub>
1610(of course only with <a href="#prandtl_layer">prandtl_layer</a>
1611switched on). Here, u<sub>*</sub>
1612and theta<sub>*</sub> are calculated from the Prandtl law
1613assuming
1614logarithmic wind and temperature
1615profiles between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_pt_b">bc_pt_b</a>)
1616must be used as bottom boundary condition for the potential temperature.</p><p>See
1617also <a href="#top_heatflux">top_heatflux</a>.</p>
1618</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_pressure"></a><b>surface_pressure</b></p>
1619</td> <td style="vertical-align: top;">R</td>
1620<td style="vertical-align: top;"><i>1013.25</i></td>
1621<td style="vertical-align: top;"> <p>Atmospheric
1622pressure at the surface (in hPa).&nbsp; </p>
1623Starting from this surface value, the vertical pressure
1624profile is calculated once at the beginning of the run assuming a
1625neutrally stratified
1626atmosphere. This is needed for
1627converting between the liquid water potential temperature and the
1628potential temperature (see <a href="#cloud_physics">cloud_physics</a><span style="text-decoration: underline;"></span>).</td>
1629</tr> <tr> <td style="vertical-align: top;">
1630<p><a name="surface_scalarflux"></a><b>surface_scalarflux</b></p>
1631</td> <td style="vertical-align: top;">R</td>
1632<td style="vertical-align: top;"><i>0.0</i></td>
1633<td style="vertical-align: top;"> <p>Scalar flux at
1634the surface (in kg/(m<sup>2</sup> s)).&nbsp; </p>
1635<p>If a non-zero value is assigned to this parameter, the
1636respective scalar flux value is used
1637as bottom (horizontally homogeneous) boundary condition for the scalar
1638concentration equation.&nbsp;This additionally requires that a
1639Neumann
1640condition must be used for the scalar concentration&nbsp;(see <a href="#bc_s_b">bc_s_b</a>),
1641because otherwise the resolved scale may contribute to
1642the surface flux so that a constant value cannot be guaranteed. Also,
1643changes of the
1644surface scalar concentration (see <a href="#s_surface_initial_change">s_surface_initial_change</a>)
1645are not allowed. <br> </p> <p>If no surface scalar
1646flux is assigned (<b>surface_scalarflux</b>
1647= <i>0.0</i>),
1648it is calculated at each timestep by u<sub>*</sub> * s<sub>*</sub>
1649(of course only with Prandtl layer switched on). Here, s<sub>*</sub>
1650is calculated from the Prandtl law assuming a logarithmic scalar
1651concentration
1652profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_s_b">bc_s_b</a>)
1653must be used as bottom boundary condition for the scalar concentration.</p>
1654</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="surface_waterflux"></a><b>surface_waterflux</b></p>
1655</td> <td style="vertical-align: top;">R</td>
1656<td style="vertical-align: top;"><i>0.0</i></td>
1657<td style="vertical-align: top;"> <p>Kinematic
1658water flux near the surface (in m/s).&nbsp; </p> <p>If
1659a non-zero value is assigned to this parameter, the
1660respective water flux value is used
1661as bottom (horizontally homogeneous) boundary condition for the
1662humidity equation. This additionally requires that a Neumann
1663condition must be used for the specific humidity / total water content
1664(see <a href="#bc_q_b">bc_q_b</a>),
1665because otherwise the resolved scale may contribute to
1666the surface flux so that a constant value cannot be guaranteed. Also,
1667changes of the
1668surface humidity (see <a href="#q_surface_initial_change">q_surface_initial_change</a>)
1669are not allowed.<br> </p> <p>If no surface water
1670flux is assigned (<b>surface_waterflux</b>
1671= <i>0.0</i>),
1672it is calculated at each timestep by u<sub>*</sub> * q<sub>*</sub>
1673(of course only with Prandtl layer switched on). Here, q<sub>*</sub>
1674is calculated from the Prandtl law assuming a logarithmic temperature
1675profile between k=0 and k=1. In this case a Dirichlet condition (see <a href="#bc_q_b">bc_q_b</a>)
1676must be used as the bottom boundary condition for the humidity.</p>
1677</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_surface"></a><b>s_surface</b></p>
1678</td> <td style="vertical-align: top;">R</td>
1679<td style="vertical-align: top;"><i>0.0</i></td>
1680<td style="vertical-align: top;"> <p>Surface value
1681of the passive scalar (in kg/m<sup>3</sup>).&nbsp;<br>
1682</p>
1683This parameter assigns the value of the passive scalar s at
1684the surface (k=0)<b>.</b> Starting from this value, the
1685initial vertical scalar concentration profile is constructed with<a href="#s_vertical_gradient">
1686s_vertical_gradient</a> and <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.</td>
1687</tr> <tr> <td style="vertical-align: top;">
1688<p><a name="s_surface_initial_change"></a><b>s_surface_initial</b>
1689<br> <b>_change</b></p> </td> <td style="vertical-align: top;">R</td> <td style="vertical-align: top;"><i>0.0</i></td>
1690<td style="vertical-align: top;"> <p>Change in
1691surface scalar concentration to be made at the
1692beginning of the 3d run (in kg/m<sup>3</sup>).&nbsp; </p>
1693<p>If <b>s_surface_initial_change</b><i>&nbsp;</i>is
1694set to a
1695non-zero
1696value, the near surface scalar flux is not allowed to be given
1697simultaneously (see <a href="#surface_scalarflux">surface_scalarflux</a>).</p>
1698</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient"></a><b>s_vertical_gradient</b></p>
1699</td> <td style="vertical-align: top;">R (10)</td>
1700<td style="vertical-align: top;"><i>10 * 0</i><i>.0</i></td>
1701<td style="vertical-align: top;"> <p>Scalar
1702concentration gradient(s) of the initial scalar
1703concentration profile (in kg/m<sup>3 </sup>/
1704100 m).&nbsp; </p> <p>The scalar gradient holds
1705starting from the height level
1706defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level
1707</a>(precisely: for all uv levels k, where zu(k) &gt;
1708s_vertical_gradient_level, s_init(k) is set: s_init(k) = s_init(k-1) +
1709dzu(k) * <b>s_vertical_gradient</b>) up to the top
1710boundary or up to
1711the next height level defined by <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>.
1712A total of 10 different gradients for 11 height intervals (10 intervals
1713if <a href="#s_vertical_gradient_level">s_vertical_gradient_level</a>(1)
1714= <i>0.0</i>) can be assigned. The surface scalar value is
1715assigned
1716via <a href="#s_surface">s_surface</a>.<br> </p>
1717<p>Example:&nbsp; </p> <ul> <p><b>s_vertical_gradient</b>
1718= <i>0.1</i>, <i>0.05</i>,&nbsp; <br>
1719<b>s_vertical_gradient_level</b> = <i>500.0</i>,
1720<i>1000.0</i>,</p> </ul> <p>That
1721defines the scalar concentration to be constant with
1722height up to z = 500.0 m with a value given by <a href="#s_surface">s_surface</a>.
1723For 500.0 m &lt; z &lt;= 1000.0 m the scalar gradient is 0.1
1724kg/m<sup>3 </sup>/ 100 m and for z &gt; 1000.0 m up to
1725the top
1726boundary it is 0.05 kg/m<sup>3 </sup>/ 100 m (it is
1727assumed that the
1728assigned height levels
1729correspond with uv
1730levels).</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="s_vertical_gradient_level"></a><b>s_vertical_gradient_</b>
1731<br> <b>level</b></p> </td> <td style="vertical-align: top;">R (10)</td> <td style="vertical-align: top;"> <p><i>10 *</i>
1732<i>0.0</i></p> </td> <td style="vertical-align: top;"> <p>Height level from
1733which on the scalar gradient defined by <a href="#s_vertical_gradient">s_vertical_gradient</a>
1734is effective (in m).&nbsp; </p> <p>The height levels
1735are to be assigned in ascending order. The
1736default values result in a scalar concentration constant with height
1737regardless of the values of <a href="#s_vertical_gradient">s_vertical_gradient</a>
1738(unless the top boundary of the model is higher than 100000.0 m). For
1739the
1740piecewise construction of scalar concentration profiles see <a href="#s_vertical_gradient">s_vertical_gradient</a>.</p>
1741</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="timestep_scheme"></a><b>timestep_scheme</b></p>
1742</td> <td style="vertical-align: top;">C * 20</td>
1743<td style="vertical-align: top;"> <p><i>'runge</i><br>
1744<i>kutta-3'</i></p> </td> <td style="vertical-align: top;"> <p>Time step scheme to
1745be used for the integration of the prognostic
1746variables.&nbsp; </p> <p>The user can choose between
1747the following schemes:<br> </p> <p><span style="font-style: italic;">'runge-kutta-3'</span><br>
1748</p> <div style="margin-left: 40px;">Third order
1749Runge-Kutta scheme.<br>
1750This scheme requires the use of <a href="#momentum_advec">momentum_advec</a>
1751= <a href="#scalar_advec">scalar_advec</a>
1752= '<i>pw-scheme'</i>. Please refer to the&nbsp;<a href="../tec/numerik.heiko/zeitschrittverfahren.pdf">documentation
1753on PALM's time integration schemes&nbsp;(28p., in German)</a>
1754fur further details.<br> </div> <p><span style="font-style: italic;">'runge-kutta-2'</span><br>
1755</p> <div style="margin-left: 40px;">Second order
1756Runge-Kutta scheme.<br>
1757For special features see <b>timestep_scheme</b> = '<i>runge-kutta-3'</i>.<br>
1758</div> <br> <span style="font-style: italic;"><span style="font-style: italic;">'leapfrog'</span><br>
1759<br> </span> <div style="margin-left: 40px;">Second
1760order leapfrog scheme.<br>
1761Although this scheme requires a constant timestep (because it is
1762centered in time),&nbsp; is even applied in case of changes in
1763timestep. Therefore, only small
1764changes of the timestep are allowed (see <a href="#dt">dt</a>).
1765However, an Euler timestep is always used as the first timestep of an
1766initiali run. When using the Bott-Chlond scheme for scalar advection
1767(see <a href="#scalar_advec">scalar_advec</a>),
1768the prognostic equation for potential temperature will be calculated
1769with the Euler scheme, although the leapfrog scheme is switched
1770on.&nbsp; <br>
1771The leapfrog scheme must not be used together with the upstream-spline
1772scheme for calculating the advection (see <a href="#scalar_advec">scalar_advec</a>
1773= '<i>ups-scheme'</i> and <a href="#momentum_advec">momentum_advec</a>
1774= '<i>ups-scheme'</i>).<br> </div> <br>
1775<span style="font-style: italic;">'</span><span style="font-style: italic;"><span style="font-style: italic;">leapfrog+euler'</span><br>
1776<br> </span> <div style="margin-left: 40px;">The
1777leapfrog scheme is used, but
1778after each change of a timestep an Euler timestep is carried out.
1779Although this method is theoretically correct (because the pure
1780leapfrog method does not allow timestep changes), the divergence of the
1781velocity field (after applying the pressure solver) may be
1782significantly larger than with <span style="font-style: italic;">'leapfrog'</span>.<br>
1783</div> <br> <span style="font-style: italic;">'euler'</span><br>
1784<br> <div style="margin-left: 40px;">First order
1785Euler scheme.&nbsp; <br>
1786The Euler scheme must be used when treating the advection terms with
1787the upstream-spline scheme (see <a href="#scalar_advec">scalar_advec</a>
1788= <span style="font-style: italic;">'ups-scheme'</span>
1789and <a href="#momentum_advec">momentum_advec</a>
1790= <span style="font-style: italic;">'ups-scheme'</span>).</div>
1791<br><br>A differing timestep scheme can be choosed for the
1792subgrid-scale TKE using parameter <a href="#use_upstream_for_tke">use_upstream_for_tke</a>.<br>
1793</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>
1794<td style="vertical-align: top;">C * 40</td> <td style="vertical-align: top;"><span style="font-style: italic;">'flat'</span></td> <td>
1795<p>Topography mode.&nbsp; </p> <p>The user can
1796choose between the following modes:<br> </p> <p><span style="font-style: italic;">'flat'</span><br> </p>
1797<div style="margin-left: 40px;">Flat surface.</div> <p><span style="font-style: italic;">'single_building'</span><br>
1798</p> <div style="margin-left: 40px;">Flow
1799around&nbsp;a single rectangular building mounted on a flat surface.<br>
1800The 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>
1801<span style="font-style: italic;"></span> <p><span style="font-style: italic;">'read_from_file'</span><br>
1802</p> <div style="margin-left: 40px;">Flow around
1803arbitrary topography.<br>
1804This 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
1805information</font></font><font color="#000000">
1806in m. These data&nbsp;<span style="font-style: italic;"></span>must
1807exactly match the horizontal grid.</font> </div> <span style="font-style: italic;"><br> </span><font color="#000000">
1808Alternatively, the user may add code to the user interface subroutine <a href="chapter_3.5.1.html#user_init_grid">user_init_grid</a>
1809to allow further topography modes.<br> <br>
1810All non-flat <span style="font-weight: bold;">topography</span>
1811modes </font>require the use of <a href="#momentum_advec">momentum_advec</a>
1812= <a href="#scalar_advec">scalar_advec</a>
1813= '<i>pw-scheme'</i>, <a href="chapter_4.2.html#psolver">psolver</a>
1814= <i>'poisfft'</i> or '<i>poisfft_hybrid'</i>,
1815<i>&nbsp;</i><a href="#alpha_surface">alpha_surface</a>
1816= 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>
1817= <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>
1818<font color="#000000"><br>
1819Note 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
1820nonzero </font><a href="#alpha_surface">alpha_surface</a>.</td>
1821</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>
1822heatflux</span></td><td style="vertical-align: top;"><p>Kinematic
1823sensible heat flux at the top boundary (in K m/s).&nbsp; </p>
1824<p>If a value is assigned to this parameter, the internal
1825two-dimensional surface heat flux field <span style="font-family: monospace;">tswst</span> is
1826initialized with the value of <span style="font-weight: bold;">top_heatflux</span>&nbsp;as
1827top (horizontally homogeneous) boundary condition for the
1828temperature equation. This additionally requires that a Neumann
1829condition must be used for the potential temperature (see <a href="chapter_4.1.html#bc_pt_t">bc_pt_t</a>),
1830because otherwise the resolved scale may contribute to
1831the top flux so that a constant value cannot be guaranteed.<span style="font-style: italic;"></span>&nbsp;</p>
1832<p><span style="font-weight: bold;">Note:</span><br>The
1833application of a top heat flux additionally requires the setting of
1834initial parameter <a href="#use_top_fluxes">use_top_fluxes</a>
1835= .T..<span style="font-style: italic;"></span><span style="font-weight: bold;"></span> </p><p>No
1836Prandtl-layer is available at the top boundary so far.</p><p>See
1837also <a href="#surface_heatflux">surface_heatflux</a>.</p>
1838</td></tr><tr> <td style="vertical-align: top;">
1839<p><a name="ug_surface"></a><span style="font-weight: bold;">ug_surface</span></p>
1840</td> <td style="vertical-align: top;">R<br> </td>
1841<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
1842<td style="vertical-align: top;">u-component of the
1843geostrophic
1844wind at the surface (in m/s).<br> <br>
1845This parameter assigns the value of the u-component of the geostrophic
1846wind (ug) at the surface (k=0). Starting from this value, the initial
1847vertical profile of the <br>
1848u-component of the geostrophic wind is constructed with <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
1849and <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
1850The
1851profile constructed in that way is used for creating the initial
1852vertical velocity profile of the 3d-model. Either it is applied, as it
1853has been specified by the user (<a href="#initializing_actions">initializing_actions</a>
1854= 'set_constant_profiles') or it is used for calculating a stationary
1855boundary layer wind profile (<a href="#initializing_actions">initializing_actions</a>
1856= 'set_1d-model_profiles'). If ug is constant with height (i.e. ug(k)=<span style="font-weight: bold;">ug_surface</span>)
1857and&nbsp; has a large
1858value, it is recommended to use a Galilei-transformation of the
1859coordinate system, if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
1860in order to obtain larger time steps.<br> </td> </tr>
1861<tr> <td style="vertical-align: top;"> <p><a name="ug_vertical_gradient"></a><span style="font-weight: bold;">ug_vertical_gradient</span></p>
1862</td> <td style="vertical-align: top;">R(10)<br>
1863</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
1864* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
1865profile of the&nbsp; u-component of the geostrophic wind (in
18661/100s).<br> <br>
1867The gradient holds starting from the height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>
1868(precisely: for all uv levels k where zu(k) &gt; <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>,
1869ug(k) is set: ug(k) = ug(k-1) + dzu(k) * <span style="font-weight: bold;">ug_vertical_gradient</span>)
1870up to the top
1871boundary or up to the next height level defined by <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>.
1872A
1873total of 10 different gradients for 11 height intervals (10
1874intervals&nbsp; if <a href="#ug_vertical_gradient_level">ug_vertical_gradient_level</a>(1)
1875= 0.0) can be assigned. The surface geostrophic wind is assigned by <a href="#ug_surface">ug_surface</a>. <br> </td>
1876</tr> <tr> <td style="vertical-align: top;">
1877<p><a name="ug_vertical_gradient_level"></a><span style="font-weight: bold;">ug_vertical_gradient_level</span></p>
1878</td> <td style="vertical-align: top;">R(10)<br>
1879</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
1880* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
1881gradient defined by <a href="#ug_vertical_gradient">ug_vertical_gradient</a>
1882is effective (in m).<br> <br>
1883The height levels are to be assigned in ascending order. For the
1884piecewise construction of a profile of the u-component of the
1885geostrophic wind component (ug) see <a href="#ug_vertical_gradient">ug_vertical_gradient</a>.<br>
1886</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_e"></a><b>ups_limit_e</b></p>
1887</td> <td style="vertical-align: top;">R</td>
1888<td style="vertical-align: top;"><i>0.0</i></td>
1889<td style="vertical-align: top;"> <p>Subgrid-scale
1890turbulent kinetic energy difference used as
1891criterion for applying the upstream scheme when upstream-spline
1892advection is switched on (in m<sup>2</sup>/s<sup>2</sup>).
1893&nbsp; </p> <p>This variable steers the appropriate
1894treatment of the
1895advection of the subgrid-scale turbulent kinetic energy in case that
1896the uptream-spline scheme is used . For further information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp; </p>
1897<p>Only positive values are allowed for <b>ups_limit_e</b>.
1898</p> </td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_pt"></a><b>ups_limit_pt</b></p>
1899</td> <td style="vertical-align: top;">R</td>
1900<td style="vertical-align: top;"><i>0.0</i></td>
1901<td style="vertical-align: top;"> <p>Temperature
1902difference used as criterion for applying&nbsp;
1903the upstream scheme when upstream-spline advection&nbsp; is
1904switched on
1905(in K).&nbsp; </p> <p>This criterion is used if the
1906upstream-spline scheme is
1907switched on (see <a href="#scalar_advec">scalar_advec</a>).<br>
1908If, for a given gridpoint, the absolute temperature difference with
1909respect to the upstream
1910grid point is smaller than the value given for <b>ups_limit_pt</b>,
1911the upstream scheme is used for this gridpoint (by default, the
1912upstream-spline scheme is always used). Reason: in case of a very small
1913upstream gradient, the advection should cause only a very small
1914tendency. However, in such situations the upstream-spline scheme may
1915give wrong tendencies at a
1916grid point due to spline overshooting, if simultaneously the downstream
1917gradient is very large. In such cases it may be more reasonable to use
1918the upstream scheme. The numerical diffusion caused by the upstream
1919schme remains small as long as the upstream gradients are small.<br>
1920</p> <p>The percentage of grid points for which the
1921upstream
1922scheme is actually used, can be output as a time series with respect to
1923the
1924three directions in space with run parameter (see <a href="chapter_4.2.html#dt_dots">dt_dots</a>, the
1925timeseries names in the NetCDF file are <i>'splptx'</i>, <i>'splpty'</i>,
1926<i>'splptz'</i>). The percentage
1927of gridpoints&nbsp; should stay below a certain limit, however, it
1928is
1929not possible to give
1930a general limit, since it depends on the respective flow.&nbsp; </p>
1931<p>Only positive values are permitted for <b>ups_limit_pt</b>.<br>
1932</p>
1933A more effective control of
1934the &ldquo;overshoots&rdquo; can be achieved with parameter <a href="#cut_spline_overshoot">cut_spline_overshoot</a>.
1935</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_u"></a><b>ups_limit_u</b></p>
1936</td> <td style="vertical-align: top;">R</td>
1937<td style="vertical-align: top;"><i>0.0</i></td>
1938<td style="vertical-align: top;"> <p>Velocity
1939difference (u-component) used as criterion for
1940applying the upstream scheme
1941when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1942<p>This variable steers the appropriate treatment of the
1943advection of the u-velocity-component in case that the upstream-spline
1944scheme is used. For further
1945information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1946</p> <p>Only positive values are permitted for <b>ups_limit_u</b>.</p>
1947</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_v"></a><b>ups_limit_v</b></p>
1948</td> <td style="vertical-align: top;">R</td>
1949<td style="vertical-align: top;"><i>0.0</i></td>
1950<td style="vertical-align: top;"> <p>Velocity
1951difference (v-component) used as criterion for
1952applying the upstream scheme
1953when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1954<p>This variable steers the appropriate treatment of the
1955advection of the v-velocity-component in case that the upstream-spline
1956scheme is used. For further
1957information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1958</p> <p>Only positive values are permitted for <b>ups_limit_v</b>.</p>
1959</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="ups_limit_w"></a><b>ups_limit_w</b></p>
1960</td> <td style="vertical-align: top;">R</td>
1961<td style="vertical-align: top;"><i>0.0</i></td>
1962<td style="vertical-align: top;"> <p>Velocity
1963difference (w-component) used as criterion for
1964applying the upstream scheme
1965when upstream-spline advection is switched on (in m/s).&nbsp; </p>
1966<p>This variable steers the appropriate treatment of the
1967advection of the w-velocity-component in case that the upstream-spline
1968scheme is used. For further
1969information see <a href="#ups_limit_pt">ups_limit_pt</a>.&nbsp;
1970</p> <p>Only positive values are permitted for <b>ups_limit_w</b>.</p>
1971</td> </tr> <tr> <td style="vertical-align: top;"> <p><a name="use_surface_fluxes"></a><b>use_surface_fluxes</b></p>
1972</td> <td style="vertical-align: top;">L</td>
1973<td style="vertical-align: top;"><i>.F.</i></td>
1974<td style="vertical-align: top;"> <p>Parameter to
1975steer the treatment of the subgrid-scale vertical
1976fluxes within the diffusion terms at k=1 (bottom boundary).<br> </p>
1977<p>By default, the near-surface subgrid-scale fluxes are
1978parameterized (like in the remaining model domain) using the gradient
1979approach. If <b>use_surface_fluxes</b>
1980= <i>.TRUE.</i>, the user-assigned surface fluxes are used
1981instead
1982(see <a href="#surface_heatflux">surface_heatflux</a>,
1983<a href="#surface_waterflux">surface_waterflux</a>
1984and <a href="#surface_scalarflux">surface_scalarflux</a>)
1985<span style="font-weight: bold;">or</span> the
1986surface fluxes are
1987calculated via the Prandtl layer relation (depends on the bottom
1988boundary conditions, see <a href="#bc_pt_b">bc_pt_b</a>,
1989<a href="#bc_q_b">bc_q_b</a>
1990and <a href="#bc_s_b">bc_s_b</a>).<br> </p>
1991<p><b>use_surface_fluxes</b>
1992is automatically set <i>.TRUE.</i>, if a Prandtl layer is
1993used (see <a href="#prandtl_layer">prandtl_layer</a>).&nbsp;
1994</p> <p>The user may prescribe the surface fluxes at the
1995bottom
1996boundary without using a Prandtl layer by setting <span style="font-weight: bold;">use_surface_fluxes</span> =
1997<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
1998case, the
1999momentum flux (u<sub>*</sub><sup>2</sup>)
2000should also be prescribed,
2001the user must assign an appropriate value within the user-defined code.</p>
2002</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
2003the treatment of the subgrid-scale vertical
2004fluxes within the diffusion terms at k=nz (top boundary).</p><p>By
2005default, the fluxes at nz are calculated using the gradient approach.
2006If <b>use_top_fluxes</b>
2007= <i>.TRUE.</i>, the user-assigned top fluxes are used
2008instead
2009(see <a href="chapter_4.1.html#top_heatflux">top_heatflux</a>).</p><p>Currently,
2010only 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
2011heat flux at the top will be automatically set to zero.</p></td></tr><tr>
2012<td style="vertical-align: top;"> <p><a name="use_ug_for_galilei_tr"></a><b>use_ug_for_galilei_tr</b></p>
2013</td> <td style="vertical-align: top;">L</td>
2014<td style="vertical-align: top;"><i>.T.</i></td>
2015<td style="vertical-align: top;"> <p>Switch to
2016determine the translation velocity in case that a
2017Galilean transformation is used.<br> </p> <p>In
2018case of a Galilean transformation (see <a href="#galilei_transformation">galilei_transformation</a>),
2019<b>use_ug_for_galilei_tr</b>
2020= <i>.T.</i>&nbsp; ensures
2021that the coordinate system is translated with the geostrophic windspeed.<br>
2022</p> <p>Alternatively, with <b>use_ug_for_galilei_tr</b>
2023= <i>.F</i>.,
2024the
2025geostrophic wind can be replaced as translation speed by the (volume)
2026averaged velocity. However, in this case the user must be aware of fast
2027growing gravity waves, so this
2028choice 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
2029advection/timestep scheme to be used for the subgrid-scale TKE.<br><br>By
2030default, the advection scheme and the timestep scheme to be used for
2031the subgrid-scale TKE are set by the initialization parameters <a href="#scalar_advec">scalar_advec</a> and <a href="#timestep_scheme">timestep_scheme</a>,
2032respectively. <span style="font-weight: bold;">use_upstream_for_tke</span>
2033= <span style="font-style: italic;">.T.</span>
2034forces the Euler-scheme and the upstream-scheme to be used as timestep
2035scheme and advection scheme, respectively. By these methods, the strong
2036(artificial) near-surface vertical gradients of the subgrid-scale TKE
2037are significantly reduced. This is required when subgrid-scale
2038velocities are used for advection of particles (see particle package
2039parameter <a href="chapter_4.2.html#use_sgs_for_particles">use_sgs_for_particles</a>).</td></tr><tr>
2040<td style="vertical-align: top;"> <p><a name="vg_surface"></a><span style="font-weight: bold;">vg_surface</span></p>
2041</td> <td style="vertical-align: top;">R<br> </td>
2042<td style="vertical-align: top;"><span style="font-style: italic;">0.0</span><br> </td>
2043<td style="vertical-align: top;">v-component of the
2044geostrophic
2045wind at the surface (in m/s).<br> <br>
2046This parameter assigns the value of the v-component of the geostrophic
2047wind (vg) at the surface (k=0). Starting from this value, the initial
2048vertical profile of the <br>
2049v-component of the geostrophic wind is constructed with <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
2050and <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
2051The
2052profile
2053constructed in that way is used for creating the initial vertical
2054velocity profile of the 3d-model. Either it is applied, as it has been
2055specified by the user (<a href="#initializing_actions">initializing_actions</a>
2056= 'set_constant_profiles')
2057or it is used for calculating a stationary boundary layer wind profile
2058(<a href="#initializing_actions">initializing_actions</a>
2059=
2060'set_1d-model_profiles'). If vg is constant
2061with height (i.e. vg(k)=<span style="font-weight: bold;">vg_surface</span>)
2062and&nbsp; has a large value, it is
2063recommended to use a Galilei-transformation of the coordinate system,
2064if possible (see <a href="#galilei_transformation">galilei_transformation</a>),
2065in order to obtain larger
2066time 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>
2067</td> <td style="vertical-align: top;">R(10)<br>
2068</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
2069* 0.0</span><br> </td> <td style="vertical-align: top;">Gradient(s) of the initial
2070profile of the&nbsp; v-component of the geostrophic wind (in
20711/100s).<br> <br>
2072The gradient holds starting from the height level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>
2073(precisely: for all uv levels k where zu(k)
2074&gt; <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>,
2075vg(k) is set: vg(k) = vg(k-1) + dzu(k)
2076* <span style="font-weight: bold;">vg_vertical_gradient</span>)
2077up to
2078the top boundary or up to the next height
2079level defined by <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>.
2080A total of 10 different
2081gradients for 11 height intervals (10 intervals&nbsp; if <a href="#vg_vertical_gradient_level">vg_vertical_gradient_level</a>(1)
2082=
20830.0) can be assigned. The surface
2084geostrophic wind is assigned by <a href="#vg_surface">vg_surface</a>.</td>
2085</tr> <tr> <td style="vertical-align: top;">
2086<p><a name="vg_vertical_gradient_level"></a><span style="font-weight: bold;">vg_vertical_gradient_level</span></p>
2087</td> <td style="vertical-align: top;">R(10)<br>
2088</td> <td style="vertical-align: top;"><span style="font-style: italic;">10
2089* 0.0</span><br> </td> <td style="vertical-align: top;">Height level from which on the
2090gradient defined by <a href="#vg_vertical_gradient">vg_vertical_gradient</a>
2091is effective (in m).<br> <br>
2092The height levels are to be assigned in ascending order. For the
2093piecewise construction of a profile of the v-component of the
2094geostrophic wind component (vg) see <a href="#vg_vertical_gradient">vg_vertical_gradient</a>.</td>
2095</tr> <tr> <td style="vertical-align: top;">
2096<p><a name="wall_adjustment"></a><b>wall_adjustment</b></p>
2097</td> <td style="vertical-align: top;">L</td>
2098<td style="vertical-align: top;"><i>.T.</i></td>
2099<td style="vertical-align: top;"> <p>Parameter to
2100restrict the mixing length in the vicinity of the
2101bottom
2102boundary.&nbsp; </p> <p>With <b>wall_adjustment</b>
2103= <i>.TRUE., </i>the mixing
2104length is limited to a maximum of&nbsp; 1.8 * z. This condition
2105typically affects only the
2106first grid points above the bottom boundary.</p> </td> </tr>
2107<tr> <td style="vertical-align: top;"><span style="font-weight: bold;"><a name="wall_heatflux"></a>wall_heatflux</span></td>
2108<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
2109kinematic sensible heat flux in W m<sup>-2</sup>
2110at the five topography faces:<br> <br> <div style="margin-left: 40px;"><span style="font-weight: bold;">wall_heatflux(0)&nbsp;&nbsp;
2111&nbsp;</span>top face<br> <span style="font-weight: bold;">wall_heatflux(1)&nbsp;&nbsp;&nbsp;
2112</span>left face<br> <span style="font-weight: bold;">wall_heatflux(2)&nbsp;&nbsp;&nbsp;
2113</span>right face<br> <span style="font-weight: bold;">wall_heatflux(3)&nbsp;&nbsp;&nbsp;
2114</span>south face<br> <span style="font-weight: bold;">wall_heatflux(4)&nbsp;&nbsp;&nbsp;
2115</span>north face</div> <br>
2116This parameter applies only in case of a non-flat <a href="#topography">topography</a>.&nbsp;The
2117parameter <a href="#random_heatflux">random_heatflux</a>
2118can be used to impose random perturbations on the internal
2119two-dimensional surface heat
2120flux field <span style="font-style: italic;">shf</span>
2121that is composed of <a href="#surface_heatflux">surface_heatflux</a>
2122at the bottom surface and <span style="font-weight: bold;">wall_heatflux(0)</span>
2123at the topography top face.&nbsp;</td> </tr> </tbody>
2124</table><br>
2125<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>
2126<p style="line-height: 100%;"><i>Last
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2128<br><br>
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