[Dart-dev] [6668] DART/trunk/models/mpas_atm/model_mod.html: a few addition changes suggested by soyoung, a typo fix,
nancy at ucar.edu
nancy at ucar.edu
Wed Dec 11 08:36:50 MST 2013
Revision: 6668
Author: nancy
Date: 2013-12-11 08:36:48 -0700 (Wed, 11 Dec 2013)
Log Message:
-----------
a few addition changes suggested by soyoung, a typo fix,
and then more futzing by me on some wordsmithing.
Modified Paths:
--------------
DART/trunk/models/mpas_atm/model_mod.html
-------------- next part --------------
Modified: DART/trunk/models/mpas_atm/model_mod.html
===================================================================
--- DART/trunk/models/mpas_atm/model_mod.html 2013-12-10 23:54:28 UTC (rev 6667)
+++ DART/trunk/models/mpas_atm/model_mod.html 2013-12-11 15:36:48 UTC (rev 6668)
@@ -53,14 +53,17 @@
<img src="../../doc/images/MPAS_grid_structure.png" alt="MPAS_grid_structure" height=600 />
<P>
The wind options during a DART assimilation
-are controlled by combinations of 4 different namelist options.
-The options control how the forward operators compute expected observation values;
-how the horizontal interpolation is computed; and how the assimilation increments
-are applied to update the wind quantities in the state vector. Preliminary
-experimental results indicate that using the zonal and meridional winds
-for the forward operator fields and using Barycentric interpolation leads
-to the smoothest estimates of wind quantities, and using increments to update
-the <i>u</i> field gives the least noisy increments. However there remains
+are controlled by combinations of 4 different namelist values.
+The values determine which fields the forward operator uses to compute expected
+observation values; how the horizontal interpolation is computed in that
+forward operator; and how the assimilation increments
+are applied to update the wind quantities in the state vector.
+Preliminary results based on real data assimilation experiments indicate that
+performance is better when the zonal and meridional winds are used as
+input to the forward operator that uses Barycentric interpolation, and when the
+prognostic <i>u</i> wind is updated by the incremental method described in
+the figure below.
+However there remain
scientific questions about how best to handle the wind fields under different
situations. Thus we have kept all implemented options available for use in
experimental comparisons. See the figure below for a flow-chart representation
@@ -305,17 +308,27 @@
<A NAME="mpas_vars_nml"></A>
<P>
-This namelist contains the list of MPAS variables that make up the DART state vector.
+The <em class=code>&mpas_vars_nml</em> namelist contains the list
+of MPAS variables that make up the DART state vector.
The order the items are specified controls the order of the data in the
-state vector, so it should not be changed without regenerating any
+state vector, so it should not be changed without regenerating all
DART initial condition or restart files.
-These variables are directly updated by the assimilation in filter.
+These variables are directly updated by the filter assimilation.
+</P>
+<P>
Any variables whose values cannot exceed a given
-minimum or maximum can be listed in <em class=code>mpas_state_bounds</em>,
-and when the data is converted back into the MPAS NetCDF files, values
-outside the allowed range will be detected. Data inside the DART
-state vector and data written to the diagnostic files
-may exceed the allowed limits.
+minimum or maximum can be listed in <em class=code>mpas_state_bounds</em>.
+When the data is written back into the MPAS NetCDF files values
+outside the allowed range will be detected and changed.
+Data inside the DART state vector and data written to
+the DART diagnostic files will not go through this test and
+values may exceed the allowed limits.
+Note that changing values at the edges of the distribution
+means it is no longer completely gaussian. In practice
+this technique has worked effectively, but if the assimilation
+is continually trying to move the values outside the permitted
+range the results may be of poor quality. Examine the diagnostics for
+these fields carefully when using bounds to restrict their values.
</P>
<div class=namelist>
@@ -349,23 +362,29 @@
<TR><TD>mpas_vars_nml</TD>
<TD>character(len=NF90_MAX_NAME)::<br />
dimension(160)
- <TD>The table that relates the MPAS-ATM variables
- to use to build the DART state vector, and the corresponding
- DART kinds for those variables. The first column in each pair must
- be the NetCDF name of a field in the MPAS file. The second column
- in each pair must be a KIND known to the DART system. See the
- <em class=file>obs_kind/obs_kind_mod.f90</em> file for known names.
- These must be generic kinds, not specific types.
+ <TD>The table that both specifies which MPAS-ATM variables will be
+ placed in the state vector, and also relates those variables
+ to the corresponding DART kinds. The first column in each pair must
+ be the exact NetCDF name of a field in the MPAS file. The second column
+ in each pair must be a KIND known to the DART system. See
+ <em class=file>obs_kind/obs_kind_mod.f90</em> for known names.
+ This file is autogenerated when DART builds filter for a particular
+ model, so run <em class=code>quickbuild.csh</em> in the work directory
+ first before examining this file. Use the generic kind list in
+ the obs_kind_mod tables, not the specific type list.
</TD>
</TR>
<TR><TD>mpas_state_bounds</TD>
<TD>character(len=NF90_MAX_NAME)::<br />
dimension(160)
- <TD> MPAS-ATM variables that need to set up lower and upper bound values.
- Columns are a variable name, min, max values, and 'CLAMP' or 'FAIL' in case
- the field goes beyond the bounds. If the bound values have 'NULL',
- the actual data range is used.</TD>
+ <TD> List only MPAS-ATM variables that must restrict their values to remain
+ between given lower and/or upper bounds.
+ Columns are: NetCDF variable name, min value, max value, and action to take
+ for out-of-range values. Either min or max can have the string 'NULL' to indicate
+ no limiting will be done. If the action is 'CLAMP' out of range values will be
+ changed to the corresponding bound and execution continues;
+ 'FAIL' stops the executable if out of range values are detected.</TD>
</TR>
</TBODY>
@@ -1439,7 +1458,7 @@
<div class="top">[<a href="#">top</a>]</div><hr />
<H2>REFERENCES</H2>
<ul>
-<li> The Data Assimilation section in the MPAS documentatino
+<li> The Data Assimilation section in the MPAS documentation
found at <a href="http://mpas-dev.github.io">
http://mpas-dev.github.io</a></li>
</ul>
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