mandatory forcing variables to drive CLM5

[xgao304]

I am in the process of generating our in-house future forcing data set to run CLM5, based on the statistical downscaling method. So far I have only used the provided forcing data sets (i.e. GSWP3). I am just wondering what are the mandatory variables to drive CLM5 among the commonly used 7 variables: tbot (air temperature), prectmms (precipitation), FSDS (solar radiation), wind (wind speed), QBOT( specific humidity), FLDS (longwave radiation), PSRF(surface pressure). As I recall, in the previous CLM versions, you don't have to have all the seven variables as input as some variables can be derived inside the codes. I am trying to look into the source codes, but am unable to find out the answer.

Any information is appreciated.

Xiang

 

[oleson]

According to the technical note, those are all required except for FLDS and PSRF:

2.32. Land-Only Mode — ctsm CTSM master documentation

escomp.github.io

 

[xgao304]

Dear Dr. Oleson,

Thanks for the quick reply and link to the detail information.

 

[xgao304]

Dr. Oleson,

I checked the link, just have one question:

Isn't PSRF required to derive the atmospheric vapor pressure

according to (2.33.10)? vapor pressure is also used to derive the FLDS if we don't provide FLDS.

Thanks,

Xiang

 

[xgao304]

OK. I see the following:

If not provided by the user, the atmospheric pressure

(Pa) is set equal to the standard atmospheric pressure

Pa, and surface pressure

(Pa) is set equal to

.

Thanks,

 

[qian yang]

dear oleson
I have a question that In the GSWP3 datasets, does solar radiation (The total solar radiation) refer to solar shortwave radiation, or solar shortwave radiation plus solar long wave radiation? I don't know much about atmosphere and would like to consult you.

 

[oleson]

Solar radiation is divided into two broad spectral bands, the visible waveband at wavelengths less than 0.7 micrometers and the near-infrared waveband at wavelengths greater than 0.7 micrometers. It does not include longwave radiation which is at wavebands greater than 4 micrometers. See here for a discussion of GSWP3 forcing data:

2.33. Land-Only Mode — ctsm release-clm5.0 documentation