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5<meta content="Siegfried Raasch" name="AUTHOR"> <meta content="20041013;13430732" name="CREATED"> <meta content="20041117;11162734" name="CHANGED"> <meta content="parallel LES model" name="KEYWORDS"> <style>
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10<body style="direction: ltr;" lang="en-US"><h3 style="line-height: 100%;">4.4 Example of a minimum
11parameter set</h3>
12<p style="line-height: 100%;">In this chapter a brief,
13simple and
14complete parameter set is described, which can be used to carry out a
15model run. The presented example is available via <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/INSTALL/example_p3d">example
16file</a> and can be used (together with the <a href="http://www.muk.uni-hannover.de/%7Eraasch/PALM_group/INSTALL/.mrun.config">configuration
17file</a> described in <a href="chapter_3.2.html">chapter
183.2)</a> for the execution of a simple model run. </p>
19<p style="line-height: 100%;">This run simulates a
20quasi-stationary,
21convective, atmospheric boundary layer with&nbsp; <font color="#000000">zero
22mean horizontal
23wind.</font> For evaluation purposes, cross sections and
24horizontally averaged vertical
25profiles of typical boundary layer variables
26are output at the end of the run. The run shall be carried out in
27batch mode on the IBM Regatta "hanni" of the HLRN.</p>
28<p style="line-height: 100%;">The parameter file necessary
29to carry
30out a run must be provided to the model as an input file under the
31local name <a href="chapter_3.4.html#PARIN">PARIN</a>
32and has the following contents:</p>
33<pre style="line-height: 100%;">&amp;inipar <a href="chapter_4.1.html#nx">nx</a> = <span style="font-style: italic;">39</span>, <a href="chapter_4.1.html#ny">ny</a> = <span style="font-style: italic;">39</span>, <a href="chapter_4.1.html#nz">nz</a> = <span style="font-style: italic;">40</span>,<br> <a href="chapter_4.1.html#dx">dx</a> = <span style="font-style: italic;">50.0</span>, <a href="chapter_4.1.html#dy">dy</a> = <span style="font-style: italic;">50.0</span>, <a href="chapter_4.1.html#dz">dz</a> = <span style="font-style: italic;">50.0</span>,<br> <a href="chapter_4.1.html#dz_stretch_level">dz_stretch_level</a> = <span style="font-style: italic;">1200.0</span>,<br> <a href="chapter_4.1.html#fft_method">fft_method</a> = <span style="font-style: italic;">'temperton-algorithm'</span>,<br> <a href="chapter_4.1.html#initializing_actions">initializing_actions</a> = <span style="font-style: italic;">'set_constant_profiles'</span>,<br> <a href="chapter_4.1.html#ug_surface">ug_surface</a> = <span style="font-style: italic;">0.0</span>, <a href="chapter_4.1.html#vg_surface">vg_surface</a> = <span style="font-style: italic;">0.0</span>,<br> <a href="chapter_4.1.html#pt_vertical_gradient">pt_vertical_gradient</a> = <span style="font-style: italic;">0.0</span>, <span style="font-style: italic;">1.0</span>,<br> <a href="chapter_4.1.html#pt_vertical_gradient_level">pt_vertical_gradient_level</a> = <span style="font-style: italic;">0.0</span>, <span style="font-style: italic;">800.0</span>,<br> <a href="chapter_4.1.html#surface_heatflux">surface_heatflux</a> = <span style="font-style: italic;">0.1</span>, <a href="chapter_4.1.html#bc_pt_b">bc_pt_b</a> = <span style="font-style: italic;">'neumann'</span>,/<br><br>&amp;d3par <a href="chapter_4.2.html#end_time">end_time</a> = <span style="font-style: italic;">3600.0</span>,<br> <a href="chapter_4.2.html#create_disturbances">create_disturbances</a> = <span style="font-style: italic;">.T.</span>,<br> <a href="chapter_4.2.html#dt_disturb">dt_disturb</a> = <span style="font-style: italic;">150.0</span>, <a href="chapter_4.2.html#disturbance_energy_limit">disturbance_energy_limit</a> = <span style="font-style: italic;">0.01</span>,<br> <a href="chapter_4.2.html#dt_run_control">dt_run_control</a> = <span style="font-style: italic;">0.0</span>,<br> <a href="chapter_4.2.html#data_output">data_output</a> = <span style="font-style: italic;">'w_xy'</span>, <span style="font-style: italic;">'w_xz'</span>, <span style="font-style: italic;">'w_xz_av'</span>, <span style="font-style: italic;">'pt_xy'</span>, <span style="font-style: italic;">'pt_xz'</span>,<br> <a href="chapter_4.2.html#dt_data_output">dt_data_output</a> = <span style="font-style: italic;">900.0</span>,<br> <a href="chapter_4.2.html#dt_data_output_av">dt_data_output_av</a> = <span style="font-style: italic;">1800.0</span>,<br> <a href="chapter_4.2.html#averaging_interval">averaging_interval</a> = <span style="font-style: italic;">900.0</span>,<br> <a href="chapter_4.2.html#dt_averaging_input">dt_averaging_input</a> = <span style="font-style: italic;">10.0</span>,<br> <a href="chapter_4.2.html#section_xy">section_xy</a> = <span style="font-style: italic;">2</span>, <span style="font-style: italic;">10</span>, <a href="chapter_4.2.html#section_xz">section_xz</a> = <span style="font-style: italic;">20</span>,<br> <a href="chapter_4.2.html#data_output_2d_on_each_pe">data_output_2d_on_each_pe</a> = <span style="font-style: italic;">.F.</span>,<br> <a href="chapter_4.2.html#dt_dopr">dt_dopr</a> = <span style="font-style: italic;">900.0</span>, <a href="chapter_4.2.html#averaging_interval_pr">averaging_interval_pr</a> = <span style="font-style: italic;">600.0</span>,<br> <a href="chapter_4.2.html#dt_averaging_input_pr">dt_averaging_input_pr</a> = <span style="font-style: italic;">10.0</span>,<br> <a href="chapter_4.2.html#data_output_pr">data_output_pr</a> = <span style="font-style: italic;">'#pt'</span>, <span style="font-style: italic;">'w&rdquo;pt&rdquo;'</span>, <span style="font-style: italic;">'w*pt*'</span>, <span style="font-style: italic;">'wpt'</span>, <span style="font-style: italic;">'w*2'</span>, <span style="font-style: italic;">'pt*2'</span>,<br> <a href="chapter_4.2.html#cross_profiles">cross_profiles</a> = <span style="font-style: italic;">' pt '</span>, <span style="font-style: italic;">' w"pt" w*pt* wpt '</span>, <span style="font-style: italic;">' w*2 '</span>, <span style="font-style: italic;">' pt*2 '</span>,<br> <a href="chapter_4.2.html#cross_xtext">cross_xtext</a> = <span style="font-style: italic;">'pot. temperature in K'</span>,<br> <span style="font-style: italic;">'heat flux in K ms&gt;-&gt;1'</span>,<br> <span style="font-style: italic;">'velocity variance in m&gt;2s&gt;-&gt;2'</span>,<br> <span style="font-style: italic;">'temperature variance in K&gt;2'</span>,<br> <a href="chapter_4.2.html#z_max_do1d">z_max_do1d</a> = <span style="font-style: italic;">1500.0</span>, /</pre><p style="line-height: 100%;"><br><br></p>
34<p style="line-height: 100%;">The initialization
35parameters (<tt><font style="font-size: 10pt;" size="2">&amp;inipar</font></tt>)
36are located at the beginning of the file. For analysis of a
37convective boundary layer of approx. 1000 m thickness the horizontal
38size of the model domain should amount to at least 2 km x 2 km. In
39order to resolve the convective structures a grid spacing of <b>dx</b>
40=
41<b>dy</b> = <b>dz</b> = <i>50 m</i>
42is enough, since the typical
43diameter of convective plumes is more than 100 m. Thereby the
44upper array index in the two horizontal directions needs to be <b>nx</b>
45= <b>ny</b> = <i>39</i>. <font color="#000000">Since in
46each case the lower array index has the value 0, 40 grid points are
47used along both horizontal directions.</font> In the vertical
48direction
49the domain must be high enough to include the entrainment processes at
50the top of the boundary layer as well as the propagation of gravity
51waves, which were stimulated by
52the convection. However, in the stably stratified region the grid
53resolution has not necessarily to be as high as within the boundary
54layer. This can be obtained by a vertical stretching of the grid
55starting
56from 1200 m via <b>dz_stretch_level</b> = <i>1200.0
57m.</i> This saves
58grid points and computing time. <font color="#800000">T</font><font color="#000000">he
59upper boundary of the model is located at (see </font><a href="chapter_4.1.html#dz_stretch_factor"><font color="#000000">dz_stretch_factor</font></a><font color="#000000">)
60&hellip; m (computed by the model)</font>.</p><p style="line-height: 100%;">Fast Fourier transformations are
61calculated using the Temperton-algorithm, which -on the IBM Regatta- is
62faster than the default system-specific algorithm (from IBM essl
63library).</p><p style="line-height: 100%;">The
64initial profiles for
65wind and temperature can be assigned via <b>initializing_actions</b>
66= <span style="font-style: italic;">'set_constant_profiles'</span>.
67The wind speed, constant with
68height, amounts to <b>ug_surface</b> = <b>vg_surface</b>
69= <i>0.0 m/s</i>. In order
70to allow for a fast onset of convection, a neutral stratified layer up
71to z
72= 800 m capped by an inversion with dtheta/dz = 1K/100 m is given:
73<b>pt_vertical_gradient</b> = <i>0.0, 1.0</i>,
74<b>pt_vertical_gradient_level</b> = <i>0.0, 800.0.</i>
75The surface
76temperature, which by default amounts to 300 K, provides the fixed
77point for the temperature profile (see <a href="chapter_4.1.html#pt_surface">pt_surface</a>).
78Convection is driven by a given, near-surface sensible heat flux via <b>surface_heatflux</b>
79= <i>0.1 K m/s.</i> A given surface sensible heta flux
80requires the
81bottom boundary condition for potential temperature to be <b>bc_pt_b</b>
82=
83<span style="font-style: italic;">'neumann'</span> .
84Thus
85all initialization parameters are determined. These can not be
86changed during the run (also not for restart runs). </p>
87<p style="line-height: 100%;">Now the run parameters (<tt><font style="font-size: 10pt;" size="2">&amp;d3par</font></tt>)
88must be specified. To produce a quasi stationary boundary layer the
89simulated time should be at least one hour, i.e. <b>end_time</b>
90= <i>3600
91s.</i> To stimulate convection, the initially homogeneous (zero)
92wind
93field must be disturbed (<b>create_disturbances</b> = <i>.T.</i>).
94These perturbations should be repeated in a temporal interval of
95<b>dt_disturb</b> = <i>150.0 s</i> until the
96energy of the
97perturbations exceeds the value <b>disturbance_energy_limit</b>
98= 0.<i>01
99m<sup>2</sup>/s<sup>2</sup></i>. After
100each time step run time
101informations (e.g. size of the timestep, maximum velocities, etc.) are
102to be written to the local file <a href="chapter_3.4.html#RUN_CONTROL">RUN_CONTROL</a>
103(<b>dt_run_control</b> = <i>0.0 s</i>).</p><p style="line-height: 100%;">Instantaneous cross section data
104of vertical velocity (<span style="font-style: italic;">w</span>)
105and potential temperature (<span style="font-style: italic;">pt</span>)
106are to be output for horizontal (<span style="font-style: italic;">xy</span>)
107and vertical (<span style="font-style: italic;">xz</span>)
108cross sections, and additionally, time averaged (<span style="font-style: italic;">av</span>) vertical cross
109section data are to be output for the vertical velocity: <span style="font-weight: bold;">data_output</span> = <span style="font-style: italic;">'w_xy'</span>, <span style="font-style: italic;">'w_xz'</span>, <span style="font-style: italic;">'w_xz_av'</span>, <span style="font-style: italic;">'pt_xy'</span>, <span style="font-style: italic;">'pt_xz'</span>. Output of
110instantaneous (time averaged) data is done after each 900 (1800)s: <span style="font-weight: bold;">dt_data_output</span> = <span style="font-style: italic;">900.0</span>, <span style="font-weight: bold;">dt_data_output_av</span> = <span style="font-style: italic;">1800.0</span>. The
111averaged data are time averaged over the last 900.0 s, where the
112temporal interval of data entering the average is 10 s: <span style="font-weight: bold;">averaging_interval</span> =
113<span style="font-style: italic;">900.0</span>, <span style="font-weight: bold;">dt_averaging_input</span> =
114<span style="font-style: italic;">10.0</span>.
115Horizontal cross sections are output for vertical levels with grid
116index k=2 and k=10, vertical cross sections are output for index j=20: <span style="font-weight: bold;">section_xy</span> = <span style="font-style: italic;">2</span>, <span style="font-style: italic;">10</span>, <span style="font-weight: bold;">section_xz</span> = <span style="font-style: italic;">20</span>. For runs on
117more than one processor, cross section data are collected and output on
118PE0: <span style="font-weight: bold;">data_output_2d_on_each_pe</span>
119= <span style="font-style: italic;">.F.</span>.</p><p style="line-height: 100%;">Output
120of vertical profiles is to be done after each 900 s. The profiles shall
121be temporally averaged<font color="#000000"> over the last
122<font color="#000000">600 </font>seconds, </font>whereby
123the temporal interval of the profiles entering the average has to be
12410 s: <b>dt_dopr</b> = <i>900.0 s</i>, <b>averaging_interval_pr</b>
125=
126<i>600.0 s</i>, <b>dt_averaging_input_pr</b> =
127<i>10.0 s.</i> The temperature
128profile including the initial temperature profile (therefore <span style="font-style: italic;">'#pt'</span>),
129the subgrid scale, resolved and total vertical sensible heat flux as
130well as the variances of the vertical velocity and the potential
131temperature are to be output:&nbsp; <b>data_output_pr</b>
132= <span style="font-style: italic;">'#pt'</span><i>,
133'w"pt&rdquo;',
134'w*pt*', 'wpt', 'w*2', 'pt*2'</i>.</p><p style="line-height: 100%;">If the data output format for
135graphic software <span style="font-weight: bold;">profil</span>
136is selected (see <a href="chapter_4.2.html#data_output_format">data_output_format</a>),
137the temperature
138profile and the individual variances are to be drawn into independent
139coordinate systems, and in contrast to this all heat flux profiles are
140to
141be
142drawn into the same system: <b>cross_profiles</b> = <span style="font-style: italic;">'pt'</span><i>,
143'w"pt"w*pt*wpt', 'w*2', 'pt*2'</i>. The legend of the x
144axes of these systems is set to <b>cross_xtext</b>= <i>'pot.
145temperature in K', 'heat flux in K ms&gt;-&gt;1', 'velocity
146variance
147in m&gt;2s&gt;-&gt;2', 'temperature variance in K&gt;2'</i>.
148The profiles are to be drawn up to a height level of <b>z_max_do1d</b>
149=
150<i>1500.0 m</i>. </p>
151<p style="line-height: 100%;">Before starting the mo<font color="#000000">del
152on the parallel computer, the number of processing elements must be
153specified.</font> Since relatively few grid points are used for
154this run, choosing of e.g. 8 PEs is sufficient. By default, a 1d domain
155decomposition along x is used on the IBM-Regatta, which means that a
156virtual processor topology (grid) of 8*1 (x*y) is used. (<span style="font-weight: bold;">Note:</span> the user may
157adjust this
158default domain decomposition with the help of the parameters <a href="chapter_4.1.html#npex">npex</a>
159and <a href="chapter_4.1.html#npey">npey</a>).
160</p><p style="line-height: 100%;">Provided that the
161parameters
162file described above are set within the file </p>
163<ul> <pre style="margin-bottom: 0.5cm; line-height: 100%;"><font style="font-size: 10pt;" size="2">~/palm/current_version/JOBS/example/INPUT/example_p3d</font></pre></ul><p style="line-height: 100%;">and that the conditions
164mentioned in the
165first sections of <a href="chapter_3.2.html">chapter
1663.2</a> are met, the model run can be started with the command </p>
167<p style="line-height: 100%;"><font face="Cumberland, monospace"><font style="font-size: 10pt;" size="2">mrun
168-d example -h ibmh -K parallel -X 8 -T 8 -t 1800 -q cdev -r
169&ldquo;d3# xy# xz# pr#&rdquo;</font></font></p>
170<p style="line-height: 100%;">The output files will appear
171in the
172directories </p>
173<blockquote style="line-height: 100%;"><tt><font style="font-size: 10pt;" size="2">~/palm/current_version/JOBS/example/MONITORING</font></tt><font style="font-size: 10pt;" size="2"><br> </font><tt><font style="font-size: 10pt;" size="2">~/palm/current_version/JOBS/example/OUTPUT
174,</font></tt></blockquote>
175<p style="line-height: 100%;">while the job protocol will
176appear in
177directory <font style="font-size: 10pt;" size="2"><font face="Cumberland, monospace">~/</font></font><tt><font style="font-size: 10pt;" size="2"><font face="Cumberland, monospace">job_queue</font></font></tt>.
178<br>
179&nbsp; </p>
180<hr><p style="line-height: 100%;"><br><font color="#000080"><font color="#000080"><a href="chapter_4.3.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_4.5.html"><font color="#000080"><img name="Grafik3" src="right.gif" align="bottom" border="2" height="32" width="32"></font></a></font></font></p><p style="line-height: 100%;"><i>Last change:&nbsp;
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