(RESOLVED) ungrib does not understand projections of ICON model data

Topics related to running the ungrib.exe program
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sekluzia
Posts: 187
Joined: Mon Oct 15, 2018 12:42 pm

(RESOLVED) ungrib does not understand projections of ICON model data

Post by sekluzia » Mon Jul 22, 2019 12:36 pm

I am trying to process ICON global model data with the WPS. I selected global 700 hPa temperature field for a specific date (https://opendata.dwd.de/weather/nwp/icon/grib/). The data are in grib2 format. However, ungrib.exe complains that the data are in unknown Projection, because the ICON is using unstructured mesh:
*** Starting program ungrib.exe ***
Start_date = 2019-07-19_00:00:00 , End_date = 2019-07-19_00:00:00
output format is WPS
Path to intermediate files is ./
GRIB2 Unknown Projection: 101
ungrib understands projections 0, 20, 30, and 40
STOP Stop in rd_grib2

Please, look also into the attached files.

Best regards,
Artur
Attachments
namelist.wps.txt
(1.6 KiB) Downloaded 32 times
Vtable.txt
(2.83 KiB) Downloaded 31 times
icon_T700.tar.gz
(4.49 MiB) Downloaded 23 times

kwerner
Posts: 2287
Joined: Wed Feb 14, 2018 9:21 pm

Re: ungrib does not understand projections of ICON model data

Post by kwerner » Tue Jul 23, 2019 3:14 pm

Hi,
Unfortunately the ungrib program is specific about the type of projection it expects. For global data sets, either a Gaussian or cylindrical equidistant projection must be used, and for regional data sets, either a Mercator, Lambert conformal, polar stereographic, or cylindrical equidistant may be used. If your data are not on one of the correct grids, then you won't be able to use it with the ungrib program.
NCAR/MMM

sekluzia
Posts: 187
Joined: Mon Oct 15, 2018 12:42 pm

Re: ungrib does not understand projections of ICON model data

Post by sekluzia » Thu Jul 25, 2019 5:52 am

Thanks a lot for your response! Could you suggest any tool for interpolating an unstructured mesh (ICON model mesh) to regular lat-lon grid which will be acceptable for the ungrib program?

mgduda
Posts: 466
Joined: Mon Feb 26, 2018 7:35 pm

Re: ungrib does not understand projections of ICON model data

Post by mgduda » Fri Jul 26, 2019 1:05 am

There are two aspects to this. The first part -- regridding the native ICON data -- can be done using the ESMF regridding utilities, for which there is an NCL interface. DKRZ have a nice document that gives an example of remapping ICON data. Once you've remapped the data onto one of the supported input projections, you'll need to write the data to a format that is usable by the WPS. Rather than writing the data to GRIB format (which is the only file format the ungrib program can read), it may be better to write the remapped ICON data directly to the "intermediate format", which is described in Chapter 3 of the ARW User's Guide.
NCAR/MMM

cachocomadreja
Posts: 1
Joined: Mon Oct 26, 2020 8:05 pm

Re: (RESOLVED) ungrib does not understand projections of ICON model data

Post by cachocomadreja » Mon Oct 26, 2020 8:07 pm

Hello! Have you managed to make it work? If so, could you please describe (at least briefly) that process? Thanks in advance!

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