initial conditions for global gfs

Submitted by steven.fletcher on Fri, 07/30/2021 - 15:33
Forum: GSI-EnKf User Support | Application Issues

I have a couple of quick questions.  I am trying to run a global comparision between two set of satellite observations for one analysis time at 2018 12 10 00. which background fields are needed for this? i.e. i know that have to be called sigf** and sfcf**? and also how do you convert the nemsio files to the resolution used in GSI?  The example that come with the code is T62 is it possible to obtain the nemsion files are this resolution already

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Submitted by wmayfield on Tue, 08/03/2021 - 12:41

Hi Steve,

Yes, nemsio background files will need to be obtained from the NOAA archive, so you will need to inquire with someone who can access that for you to obtain the background files. To use them change the namelist option use_gfs_nemsio=.true., and change the part of the run script that copies the background, to copy the desired nemsio forecast files to be named sigf** and sfcf**, e.g. "cp $BK_ROOT/gfs.t<inithour>z.atmf<fhour>.nemsio  ./sigf06" and so on. They will be in whatever resolution GFS was run at the time, so I believe for your proposed date you will get files at a 1534 resolution. There is no need to convert the nemsio file to another resolution, as the GSI analysis resolution can be specified independently from the background. If you look in the run script at the GFSCASE options, you will see that T574 matches the 1534 GFS resolution (JCAP_B, must match the background file), and perform the analysis resolution (JCAP, check how these also set LATA, LONA) at 574. You can try other resolutions for the analysis and check how GSI uses them in stdout. The user's guide also has some information about these resolution namelist options.

 

Will

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Submitted by steven.fletcher on Tue, 08/03/2021 - 13:06

Thanks will, as a last resort can the GSI read grb2 files? I have emailed Daryl Kleist to see if he can point me in the direction of the files, i was able to for the fv3 last year but cannot find that repository any where now

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