GRIB1 file format

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airace
Posts: 2
Joined: Mon Dec 22, 2014 11:03 am

GRIB1 file format

Post by airace » Mon Dec 22, 2014 11:10 am

Hello everyone,
I am a new user of WRFEMS (especially for sailing purposes, so I am basically interested in UGRD:VGRD @10m) and I already start to have problems.
I have been able to configure, prep, run and post a 24h simulation. Now I am familiar with the configuration files. Problem is the following:

- I run a ARW simulation on a lat-lon grid
- I process the output data and produce grib1 and grib2 datasets
- I process grib2 datasets in order or extract only UGRD:VGRD at 10m above sea level
- I convert grib2 to grib1
- When I try to open the .grb file with Panoply, or XYGrib or some Weather routing program I get error. The most detailed error message I have been able to observe is (Unsupported GDS type = 203) from Panoply.
- On the other hand I am perfectly capable of opening the files with MATLAB and display the data correctly.

So the problem should be that the GRIB1 file that I am producing is not entirely compatible with the viewer.

Any suggestion on how to configure ems_post to produce a GRIB1 file that can be visualized using, i.e. XYGRIB ?

Thanks and regards
Andrea

smartie
Posts: 97
Joined: Sat May 21, 2011 7:34 am

Re: GRIB1 file format

Post by smartie » Mon Dec 22, 2014 4:05 pm

Panoply or any other Grib viewer won't be able to read the output files unless you have configured it with the correct vtable.
Panoply will read the native netCDF output.
IDV is a nice package that will read and plot WRFEMS Grib 1 and 2 and the native WRF netCDF files-
http://www.unidata.ucar.edu/software/idv/
or you can use the built-in GRADS.

airace
Posts: 2
Joined: Mon Dec 22, 2014 11:03 am

Re: GRIB1 file format

Post by airace » Mon Dec 22, 2014 9:11 pm

Thanks for your reply,
I have made some progress, now the GRIB1 files can be correctly opened with Panoply. But I really need to have a GRIB1 output which is compatible with other GRIB1 viewers or weather routing software such as Expedition, Blue Water Racing etc. as I want to distribute wx files during local sailing competitions.

I guess it's only a matter of configuring the GRIB1 header correctly. Again, I am capable of opening the emsprd/grib files with the read_grib MATLAB function and they look pretty normal, so it should be just a matter of simple tweaking. I will look into the vtables setup but I supposed it was for input variables.

rgds
andrea

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