• Created by Unknown User (clement.bouvier@helsinki.fi) on Jul 27, 2022

Hello everyone

I'm seeking to reduce the amount of data output to the northern hemisphere only.
I saw that with FullPos (https://confluence.ecmwf.int/download/attachments/55118972/fullpos_usersguide.pdf?version=1&modificationDate=1455131954373&api=v2&download=true) it is possible to force the output to display only a specified area. This is interesting and I would like to do it on the entirety of the Northern Hemisphere. Does anyone know a simpler solution than the one presented in this document exist or shall I follow the written instruction?
Thanks again for your time and help.

Best regards,

Clément Bouvier

3 Comments

  1. Unknown User (gdcarver113@outlook.com)

    Bonjour Clément 

    Looks like the OpenIFS team haven't responded but I used to work at ECMWF so I'll answer.  As the FULLPOS manual is over 60 pages I've not looked through it to find the method you mentioned. If you point me to the page, I'll have a look.

    However, many items mentioned in there refer to the MeteoFrance configuration of IFS which is capable of limited area forecasts. ECMWF's IFS (and therefore OpenIFS) only runs as a global model.  Note also IFS outputs the main prognostic variables as spectral data (which is intrinsically global), it's not possible to restrict their output to NH only.  For other model fields output as gridpt data I'm not aware of any settings in FULLPOS that would restrict the data to NH only.  There is the DDH facility which is used for diagnostic primarily (though that doesn't get a mention in the FULLPOS manual I see), and it rather tricky to setup.

    Personally, I think you'd spend more time trying to get the model to output NH only for the fields you need than output global fields and then deal with the data reduction in post-processing.

    Cheers.

  2. Unknown User (clement.bouvier@helsinki.fi)

    Hello Ryan,

    Thank you for your helpful answer, I will look for post-processing solution to my problem.

    Cheers

  3. Marcus Koehler

    Hi Clément,

    I agree that postprocessing of the output is the best solution. As you may remember, when we discussed previously your question when you contacted me through OpenIFS support, I suggested at the time that you could look into the Metview package for postprocessing of GRIB data files.  Metview is capable of reading boh spectral and gridpoint data and I believe this would be a good tool for this task.  But perhaps some OpenIFS users have already developed other methods or used other tools to achieve this, so it's a good idea to post here on the Forum. 

    Best wishes,  Marcus