(
By this stage you have successfully downloaded the
test data for the tutorial and are ready to run 3DVAR observation preprocessor
(3DVAR_OBSPROC). If not, return to a.
Downloading Test Data.
At any stage, to consult documentation, you may like
to return to the 3DVAR web-page.
Chapter 3 of the 3DVAR Technical
Note describes 3DVAR_OBSPROC in more detail. Or you can view the Online
3DVAR Tutorial Presentations.
1. Accessing and compiling the 3DVAR_OBSPROC code
First, go to your working directory and download the 3DVAR_OBSPROC from 3DVAR_code_data by clicking "3DVAR Pre-processing Source Code". Once you have it on your machine, type the following to unzip and untar it:
gunzip 3DVAR_OBSPROC.tar.gz
tar -xvf 3DVAR_OBSPROC.tar
After this, you should see a directory 3DVAR_OBSPROC/
created in your working directory. If so remove the .tar file
rm 3DVAR_OBSPROC.tar
and cd to this directory:
cd 3DVAR_OBSPROC
Read the README file. To compile 3DVAR_OBSPROC, type
make
Once this is complete (a minute or less on most
machines), you can check for the presence of the 3DVAR_OBSPROC executable by
issuing the command (from the 3DVAR_OBSPROC directory)
ls –l src/3dvar_obs.exe
-rwxr-xr-x 1 mmm01
system 591184
2. Running 3DVAR_OBSPROC
OK, so now you’ve compiled 3DVAR_OBSPROC. Before
running the 3dvar_obs.exe, create the namelist file namelist.3dvar_obs and
edit (see README.namelist for details);
cp namelist.3dvar_obs.sample
namelist.3dvar_obs
then edit namelist.3dvar_obs.
In this tutorial, all you need to change are the
locations of the observation (ob.little_r) and first guess (fg)
files, and the analysis time (which for this case is 12 UTC 19 August
1999).
Note that the default settings in Makefile is
to use a namelist.3dvar_obs with the templet of namelist.3dvar_obs.sample,
which needs a first guess file fg (MMINPUT or MMOUTPUT) as the input
file. If you do not have a first guess file ready to be used, you still can run
3DVAR_OBSPROC, but you need to modify Makefile by deleting the CPP option
-DBKG prior to compiling, and must use namelist.3dvar_obs.sample1 as
the templet of the namelist.3dvar_obs file.
To run the 3DVAR_OBSPROC, type
3dvar_obs.exe
>& 3dvar_obs.out
Take a look at the 3dvar_obs.out file to acquaint
yourself with details of the run.
3. Looking at 3DVAR_OBSPROC output.
When the 3dvar_obs.exe was completed normally, you’ll have an
observation data file: obs_gts.3dvar, which will be used as
the input to 3dvar. Before running 3dvar, there is a utility to look at the
data distribution for each type of observations.
1) cd MAP_plot;
2) Modify the shell script Map.csh
to set the time window and resulted OBS data file name: obs_gts.3dvar including path;
3) Type
Map.csh
the configure.user will
be automatically picked up for your computer system (IBM, DEC, or PC
Linux) when you type Map.csh;
4) When the job has
completed, you’ll have a gmeta file gmeta.{analysis_time}
which contains plots of data distribution for each
type of observations contained in the OBS data file: obs_gts.3dvar. To view this, type
idt gmeta.1999081912
4. Saving necessary file for 3DVAR and clean
3DVAR_OBSPROC
In this tutorial, we are storing data in a directory
defined by the environment variable $DAT_DIR. Having successfully created your own observation file (obs_gts.3dvar),
copy it to $DAT_DIR using the command (from 3DVAR_OBSPROC directory)
mv obs_gts.3dvar $DAT_DIR/ob
Finally, to clean up the
3DVAR_OBSPROC directory, type
make clean
5. What next?
OK, you’ve now created the observation file and
looked at some plots of observations, now you’re ready to move on to 3DVAR:
Miscellanies:
1) When you run 3dvar_obs.exe, and you did not obtain the file obs_gts.3dvar, please check 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 you run 3dvar_obs.exe and got a error as 'Error in NAMELIST record 2' in 3dvar_obs.out file, please check if your namelist.3dvar_obs file matches with the Makefile settings. Either Your namelist.3dvar_obs file or Makefile need to be modified, then re-compile and re-run the job;
3) From the *.diag files, you may find which observation report caused the job failed;
4) In most cases, the job failed was caused by incorrect input files names, or the specified analysis time, time window, etc. in namelist.3dvar_obs;
5) If users still cannot figure out the troubles, please inform us and pass us your input files including the namelist file, and printed file 3dvar_obs.out.
Trouble Shooting:
1. If you have questions, ask mesouser.