How to prep met files for MPAS initialization

[afernandezody]

Hello,
I'm trying to tailor the files to run a new MPAS simulation. The atmosphere initialization app processes all the geographic data but crashes when it gets to read the met data as it looks for files with a CFSR prefix. I downloaded files from the RDA server but have 2 questions:
Q1 - I was able to download 10 types of files: egyh, egyl, flxf, flxl, ipvh, ipvl, pgbh, pgbl, ocnf, and ocnh. I really don't know which data each file holds, but my question is which one is the most appropriate for MPAS simulations?
Q2 - After untarring any of the previously mentioned packages, there are several GRIB2 files. A couple of posts indicate the need to run ungrib to generate intermediate files. However, I was unable to locate any example of namelist.wps for MPAS. Is there such or should I modify some from a WRF simulation?
Thanks.

 

[Ming Chen]

Please see my answers below:

Hello,
I'm trying to tailor the files to run a new MPAS simulation. The atmosphere initialization app processes all the geographic data but crashes when it gets to read the met data as it looks for files with a CFSR prefix. I downloaded files from the RDA server but have 2 questions:
Q1 - I was able to download 10 types of files: egyh, egyl, flxf, flxl, ipvh, ipvl, pgbh, pgbl, ocnf, and ocnh. I really don't know which data each file holds, but my question is which one is the most appropriate for MPAS simulations?

Did you want to use CFSR as input data for running MPAS? Is it possible that you use GFS? I recommend using GFS because GFS is well tested as input for MPAS. You can download GFS data from NCAR RDA Dataset d084001

Q2 - After untarring any of the previously mentioned packages, there are several GRIB2 files. A couple of posts indicate the need to run ungrib to generate intermediate files. However, I was unable to locate any example of namelist.wps for MPAS. Is there such or should I modify some from a WRF simulation?

UNGRIB is a component of WPS (WRF preprocess package). It is not included in MPAS modeling system. If you are not familiar with WPS/WRF, please take a look at the the instruction here. You may need to install WPS first, then run ungrib.exe to process GFS data and produce an intermediate format datafile that MPAS accepts.

Please try and let us know if you have any questions.

Thanks.

 

[afernandezody]

Got it. What threw me off was the default value to be set to CFSR as I was unfamiliar with it (even saw some posts discussing the use of ERA5). However, using GFS data is a lot easier (I prefer downloading the data from the S3 bucket as it is usually faster than using the RDA dataset).
Thanks.

 

[mgduda]

In case they're helpful, here are a few notes that I had written up elsewhere on compiling and running ungrib.

1) Clone the WPS repository from GitHub:

git clone https://github.com/wrf-model/WPS.git

2) Configure the WPS to not require WRF and to build internal GRIB2 libraries:

cd WPS
./configure --nowrf --build-grib2-libs

When prompted, choose a configuration option that matches the compilers that you have on your system. Choosing a "(serial)" option is best, as the "(dmpar)" options don't influence the operation of the ungrib program.

3) Compile the ungrib program only:

./compile ungrib

Once you've successfully compiled the ungrib program (there should be an ungrib.exe binary in your WPS directory), you can process a set of GRIB files into intermediate files. Assuming these GRIB files are in /filesystem/somewhere with names matching gfs*, there are four steps:

1) Symbolically link the GRIB files into the WPS directory with names GRIBFILE.AAA, GRIBFILE.AAB, GRIBFILE.AAC, etc. This can be done using the link_grib.csh script:

./link_grib.csh /filesystem/somewhere/gfs*

2) Symbolically link the variable table (Vtable) from the ungrib/Variable_Tables directory into the WPS directory as the file Vtable; e.g., for GFS GRIB files:

ln -s ungrib/Variable_Tables/Vtable.GFS Vtable

3) Edit the namelist.wps file to set the first start_date and end_date values to the starting and ending dates of the GRIB files that you will be processing. Also set the interval_seconds value to the interval between GRIB files. For example, if we have six hours of GFS files every three hours (three files total), we might set:

&share
start_date = '2024-10-18_00:00:00',
end_date = '2024-10-18_06:00:00',
interval_seconds = 10800
/

4) Run ungrib.exe to produce intermediate files with the prefix FILE:

./ungrib.exe

Once you have intermediate files with the FILE prefix, you can just change 'CFSR' to 'FILE' in your namelist.init_atmosphere file when running the init_atmosphere_model program.

 

[Ming Chen]

@mgduda

Many thanks for the detailed step-by-step instruction, which is very helpful !