How to modify PFTS in CLM5.0？

[zqzq]

Dear all，

I have the following three questions for your advice，1. Which file in the surface data generated by CLM5.0 contains the vegetation type of the underlying surface for single-point simulation? 2. Which one of PFTDATA_MASK, PCT_NAT_PFT, LANDFRAC_PFT? 3.If the PFTS in the surface data does not match the actual situation, can you directly modify the values of the PFTS-related variables in the two nc files surfdata_1x1_PAILONG_simyr2000.nc and surfdata_1x1_PAILONG_simyr1850.nc



Thanks Reply

 

[oleson]

1. The file pointed to by fsurdat in the lnd_in namelist is the surface data file that contains vegetation type, etc.
2. PCT_NAT_PFT
3. Yes. Keep in mind the following rules:

PCT_CROP
PCT_NATVEG
PCT_LAKE
PCT_WETLAND
PCT_GLACIER
PCT_URBAN

The sum of these has to equal 100% at each gridcell. Note that unlike other landunits, there are up to three urban landunits per gridcell.

Also on the surface dataset is:

PCT_CFT

The sum of the two crops types (15 - C3 Unmanaged Rainfed Crop and 16 - C3 Unmanaged Irrigated Crop) must equal 100%, even for gridcells where PCT_CROP is zero (in this case crop type 15 is set to 100% and crop type 16 is set to 0%). These two crop types represent the non-irrigated/irrigated fractions on the crop landunit given by PCT_CROP.

Also on the surface dataset is:

PCT_NAT_PFT

The sum of these must equal 100%. They represent the fractions of pfts on the natural vegetated landunit given by PCT_NATVEG.

 

[zqzq]

1. The file pointed to by fsurdat in the lnd_in namelist is the surface data file that contains vegetation type, etc.
2. PCT_NAT_PFT
3. Yes. Keep in mind the following rules:

PCT_CROP
PCT_NATVEG
PCT_LAKE
PCT_WETLAND
PCT_GLACIER
PCT_URBAN

The sum of these has to equal 100% at each gridcell. Note that unlike other landunits, there are up to three urban landunits per gridcell.

Also on the surface dataset is:

PCT_CFT

The sum of the two crops types (15 - C3 Unmanaged Rainfed Crop and 16 - C3 Unmanaged Irrigated Crop) must equal 100%, even for gridcells where PCT_CROP is zero (in this case crop type 15 is set to 100% and crop type 16 is set to 0%). These two crop types represent the non-irrigated/irrigated fractions on the crop landunit given by PCT_CROP.

Also on the surface dataset is:

PCT_NAT_PFT

The sum of these must equal 100%. They represent the fractions of pfts on the natural vegetated landunit given by PCT_NATVEG.

thank you for your reply，The underlying surface of the research site I use CLM5.0 for single-point simulation is only grass，But the terrain data generated by clm5.0 is shown in the attached picture，In order to match the actual situation, do I need to set the value of non-polar C3 grassland in PFTS to 100?As you said, do I only need to modify this nc file directly to complete this operation?

 

[oleson]

If you want only grassland, then you may also need to set PCT_NATVEG to 100% (and any other non-zero landunits to 0%).