b. WRF-Var
Observation Preprocessor (OBSPROC)
By this stage you have
successfully downloaded the test data for the tutorial and are ready to run OBSPROC,
the WRF-Var observation pre-processor. If haven't
downloaded the data, return to a. Downloading Test Data.
i. Compiling OBSPROC code
Change
directories to
make
Once this is
complete, you can check for the presence of the OBSPROC executable by issuing
following command (from “var/obsproc” directory)
ls -l
ii. Running
3DVAR_OBSPROC
OK, so now
you have compiled “OBSPROC”. Before running “3dvar_obs.exe”, create the desired
namelist file, namelist.3dvar_obs (see README.namelist for details). For this tutorial, a file
named “namelist_3dvar_obs.wrfvar-tut” has already been created in the "var/obsproc" directory. Thus, proceed as follows.
cp
namelist.3dvar_obs.wrfvar-tut namelist.3dvar_obs
[
edit
In this
tutorial, all you need to change is the full path to the observation file (ob.little_r) file, the grid dimensions (nestix
= nestjx = 45), the resolution (dis
= 200[km]), and the time window (2003-01-01_09 through 2003-01-01_15 centered
at 2003-01-01_12).
To run the
3DVAR_OBSPROC, type
./3dvar_obs.exe >&! 3dvar_obs.out
iii. Looking at
3DVAR_OBSPROC output.
Once
3dvar_obs.exe has completed successfully, you will see an observation data
file, obs_gts.3dvar, in the “obsproc” directory; this
is the input observation file to WRF-Var. Before
running WRF-Var, you may like to learn more about
various types of data you are aiming to assimilate for this case, its geographical
distribution, etc. The obs_gts.3dvar file is in ASCII format, and so you can
easily view it.
1) cd MAP_plot
2) Modify
the script Map.csh to set the time window and full
path of input observation file (obs_gts.3dvar).Precisely, the following string in
this script as follows.
TIME_WINDOW_MIN = ‘2007010121’
TIME_ANALYSIS = ‘2007010200’
TIME_WINDOW_MAX = ‘2007010203’
OBSDATA = ./obs_gts.3dvar
3) Map.csh
Note: the configure.user
file will be automatically picked up for your computer system when you run Map.csh.
4) When the
job has completed, you will have a NCAR Graphics meta-file called gmeta.{analysis_time},
corresponding to analysis_time=2007010200. This
contains plots of data distribution for each type of observations contained in
the obs_gts.3dvar observation file. To view this, type
idt gmeta.2007010200
It will display, frame by
frame, the geographical distribution of various types of data which are listed
in the header of “obs_gts.3dvar”. Following is the geographic distribution of the
“sonde” observations for this case.
iv. Saving necessary
file for WRF-Varand clean OBSPROC
In this tutorial, we are
storing data in a directory defined by the environment variable $DAT_DIR.
mv
obs_gts.3dvar $DAT_DIR/ob/2007010200/ob.ascii
Finally, to clean up the “var/obsproc” directory, type following command in the same
directory
make clean
v.
Miscellanies
1) When running 3dvar_obs.exe, if you
did not obtain the file obs_gts.3dvar, please check the 3dvar_obs.out file to
see where the program aborted. Usually there is information in this file to
tell you what is wrong;
2) When running 3dvar_obs.exe, if you got
an error such as 'Error in NAMELIST record 2' in 3dvar_obs.outfile, please
check if your namelist.3dvar_obs file matches the Makefile
settings. Either your namelist.3dvar_obs file or your Makefile
need to be modified. After making corrections, re-compile and re-run the job;
3) From the *.diag
files, you may find which observation report caused the failure of a job.
4) In most cases, a job failure is
caused by incorrect input file names or an incorrectly specified analysis time,
time window, etc., in namelist.3dvar_obs;
5) If none of the above are helpful in
resolving the problem, please inform us and pass us your input files, including
the namelist file and the 3dvar_obs.out file.
vi. What next?
OK, you have now created
the observation file and looked at some plots of observations, now you are
ready to move on to WRF-Var:
Trouble Shooting:
1. If you have questions, ask
wrfhelp@ucar.edu.