(RESOLVED) ERA-Interim data - using specific humidity instead of RH

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Joined: Thu Jul 02, 2020 3:57 pm

(RESOLVED) ERA-Interim data - using specific humidity instead of RH

Post by qinchi_97 » Fri Jul 03, 2020 1:30 am

I'm running WRF with ERA-Interim data(pressure level, RH not included), can I use specific humidity, 2m temperature and 2m dewpoint temperature to calculate relative humidity instead of ungribbing it from ERA-interim RH data file during the ungrib procedure?
I simply add SPECHUMD to the Vtable.ECMWF and others are the same.
Vtable.png (11.59 KiB) Viewed 186 times
Then I notice this RH data calculated from SPECHUMD, 2m TT and 2m DEWPT are different from the ungribbed ERA-Interim RH data in met_em*.nc, what could be the problem?

Thanks so much,

Posts: 1926
Joined: Wed Feb 14, 2018 9:21 pm

Re: Vtable for ERA-Interim data

Post by kwerner » Wed Jul 08, 2020 5:02 pm

It's hard to say what the difference is, but if you have specific humidity available, you do not need to worry about having or calculating RH. That process will be done for you. See this section of the Users' Guide, regarding mandatory input data:
https://www2.mmm.ucar.edu/wrf/users/doc ... cal_Fields

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