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19<h2 style="line-height: 100%;"><font size="4">4.0 Steering parameters</font></h2>
20<p style="line-height: 100%;">Before carrying out a model run, the user
21has to /determine/ a data set - the model parameters - e.g. how
22many grid points are to be used, how large the horizontal and
23vertical grid spacing should be, which kind of boundary conditions are
24to be used for the individual variables, which numerical schemes
25implemented in the model are to be used, how long the simulated time
26should be, at which times and points plot output are supposed to be
27made, etc. <br>
29<p style="line-height: 100%;">These data are assigned with the help of
30so-called ?“NAMELIST-driven input”? (FORTRAN - NAMELIST –
31input). The ?gewählten? values of the model parameters are written
32into an ASCII file with fixed format, which is expected by the model as
33an input
34file under the local name <a href="chapter_3.4.html#PARIN">PARIN</a>.
35On this file the parameters are represented by their variable names
36they have in the model. These parameters can be assigned one or more
37values, depending on the type and size the variable has. The following
38example shows the format of the file
39PARIN: <br>
40&nbsp; </p>
42  <p style="line-height: 100%; font-family: monospace;">&amp;inipar nx
43= 79, ny = 79, nz = 40, <br>
44&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dx = 50.0, dy = 50.0, dz =
4550.0, <br>
46&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; initializing_actions =
47"set_1d-model_profiles", <br>
48&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; prandtl_layer = .TRUE.,/ </p>
49  <p style="line-height: 100%; font-family: monospace;">&amp;d3par&nbsp;
50end_time = 9000.0, section_xy = 1, 10, 20,/ </p>
51  <p style="line-height: 100%; font-family: monospace;">&amp;packagename
52var1 = .TRUE. / </p>
53  <p style="line-height: 100%;"><span style="font-family: monospace;">&amp;userpar
54abcd = 1234,0,/ </span><br>
55&nbsp; <br>
58<p style="line-height: 100%;">The parameters are separated into four
59different groups which all start with the so-called NAMELIST group
61These are <span style="font-family: monospace;">&amp;inipar</span>, <span
62 style="font-family: monospace;">&amp;d3par</span> and <span
63 style="font-family: monospace;">&amp;packagename</span> as well as <span
64 style="font-family: monospace;">&amp;userpar</span>. In each case a
65group is terminated with one backslash ("/"). Between the beginning of
66the line and the group name at least one blank has to be typed. Between
68group names and the "/", the
69values are assigned to the variables. The example shows that in
70principle all FORTRAN data types are allowed. For more details
71concerning the NAMELIST syntax, refer to
72appropriate FORTRAN manuals. <br>
74<p style="line-height: 100%;">Parameters belonging to the group <span
75 style="font-family: monospace;">inipar</span> are first read by PALM.
76These are the initialization parameters. Second, the so-called run
77parameters belonging to the group <span style="font-family: monospace;">d3par</span>
78are read in, then the parameters for steering the optional software
79packages (group <span style="font-family: monospace;">packagename,</span>
80the string <span style="font-family: monospace;">"packagename"</span>
81must be replaced by the NAMELIST
82group name of the respective package) as well as user-defined
84(group <span style="font-family: monospace;">userpar</span>). The four
85groups must be given in this order, the last groups, <span
86 style="font-family: monospace;">packagename</span> and <span
87 style="font-family: monospace;">userpar</span>, may
88be omitted. If several software packages are selected
89(see chapter <a href="chapter_3.7.html">3.7</a>),
90further NAMELIST groups may be inserted before the group <span
91 style="font-family: monospace;">userpar</span>.
93<p style="line-height: 100%;"><b>The initialization, run</b> and
94<b>package parameters</b> differ as follows: </p>
96  <li>
97    <p style="margin-bottom: 0cm; line-height: 100%;">The <b>initialization
98parameters </b>are steering the basic settings of the model run. They
99define e.g. the number of the grid points, the numerical schemes to be
100used, initial and boundary conditions to be applied, how the
101three-dimensional fields are initialized at the beginning of a model
102run (constant&nbsp; value profiles or 1D-model-pre-run, the initial
103temperature profile etc.). These parameters apply to the total model
104run and thus can not be changed with restart runs! If one tries to
105change these values within the NAMELIST input file of a restart run,
106then these changes are ignored (sole exception is the parameter <a
107 style="font-family: monospace;"
108 href="chapter_4.1.html#initializing_actions">initializing_actions</a><font
109 style="font-size: 10pt;" size="2">, </font>which must be given the
110value<span style="font-family: thorndale,serif,mon;"> </span><span
111 style="font-family: monospace; font-style: italic;">read_restart_data</span><span
112 style="font-family: thorndale,serif,mon;"> for </span>restart runs). <br>
113&nbsp; </p>
114  </li>
115  <li>
116    <p style="margin-bottom: 0cm; line-height: 100%;">The <b>run
117parameters</b> are generally steering actions to be carried out during
118a model run. One can select for example, at which times plot output
119should happen and which variables are to be written. Additionally one
120can (and must) specify the time to be simulated. Run parameters only
121apply to the actual run (job) and with each restart run other values
122may be declared (if runs are restarted automatically, parameters will
123usually keep their values, provided that the NAMELIST input file was
124not changed by the user in the meantime). <br>
125&nbsp; </p>
126  </li>
127  <li>
128    <p style="line-height: 100%;"><b>Package parameters</b> behave like
129    <b>run parameters</b>. Package parameters determine the behavior of
130the additional (not user-defined) software packages . </p>
131  </li>
133<p style="line-height: 100%;">The user-defined parameters are assigned
134by the user within the NAMELIST group name <tt>&amp;userpar</tt> (see <a
135 href="chapter_3.5.2.html">chapter
1363.5.2</a>). They steer actions programmed by the user. By default,
137this group has only one parameter (<a href="chapter_4.3.html#region">region</a>).
138If the
139user don't want to assign any values to the user-defined&nbsp;
140parameters, the group<span style="font-family: monospace;"> userpar
141</span>may be omitted. The group name <span
142 style="font-family: monospace;">&amp;userpar</span>
143can be changed by the user in the user-defined code. In
144addition to this, further NAMELIST groups may also be declared (all
145within routine <span style="font-family: monospace;">user_parin</span>
146in file <span style="font-family: monospace;">user_interface.f90</span>).
147<a href="chapter_4.4.html">Chapter
1484.4</a> shows a simple but complete example of the input file PARIN.
149This example file can be used together with the configuration file
150(described in <a href="chapter_3.2.html">chapter
1513.2</a>) for the execution of a model test run. </p>
152<p style="line-height: 100%;">PALM assigns default
153values to nearly all parameters. They become effective
154if no other assignments are given in the parameter file. These
155default values as well as the parameter name, type and its
156explanation are described in the lists of the following subsections. <br>
157&nbsp; </p>
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169&nbsp;<span style="font-style: italic;">Last change:</span> 15/04/05
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