Compset question

[heyaqian1987@gmail_com]

Dear all,

We are trying to replace the land cover/use (LCLU) map in the CLM in 1984 and 2014, respectively, using high-resolution/accuracy LCLU derived from remotely sensed data. Then we want to run two experiments: (1) a 30-year run with 1984 LCLU data and (2) a 30-year run with 2014 LCLU data. By differencing these two experiments, we can explore how land cover/use change impacts on local climate in the northwestern US.

I searched a little bit and found we may use the F2000climo compset with active land and atmosphere models or the corresponding I2000clm50Sp compset with land model only.

Can anyone help to have a look if the compsets are proper?

Thanks a lot.

Best regards,
Yaqian

 

[oleson]

Those would give you land satellite phenology (SP, prescribed leaf/stem area and canopy heights) which would allow you to explore the biophysical impacts of landcover/use change. If you wanted to look at biogeochemical impacts (i.e., carbon/nitrogen and prognostic leaf area) you'd need to choose a BGC or BGC-CROP compset (you could specify this by the compset longname). However, this would likely required longer spinups.

 

[heyaqian1987@gmail_com]

Hi Keith,

Thank you for the response. So if we want to explore further like impacts of land cover/use change on ecosystem productivity (e.g., GPP), we'd need to use BGC or BGC-CROP, correct? If we do so, how long do we need to spinups?

Thanks,
Yaqian

 

[oleson]

GPP is essentially FPSN (photosynthesis) in SP mode. And it would be constrained by the prescribed LAI. But if you want to look at something like NEE or NEP, then you'd need either BGC or BGC-CROP.
There is some explanation of spinups here in the User's Guide:

1.5.5. Spinup of CLM5.0-BGC-Crop — ctsm release-clm5.0 documentation

However, most of the BGC spinup time is spent spinning up soil carbon in cold regions. If you're not running globally, e.g., over the northwestern U.S., then the spinup time should be greatly reduced. I don't really have an idea how long it would take in that region.

 

[heyaqian1987@gmail_com]

Hi Keith,

I understand it now. My study region surrounds Alaska. I feel it is a cold region. I will explore the examples you provided.

Thanks a lot for your guidance.

Yaqian