weichun_tao@kaust_edu_sa
New Member
These questions I have asked Sam through email, for sharing experience, I'm now posting all the QA here.
A.
Sam:
1) It's your choice. You do not have to modify the raw data. You could just modify the surface data. To modify any of these files, you need a method that can read, change, and write a netcdf file. This could be a fortran program, or matlab, idl, ncl, netcdf operators, the tools ncdump (to make .nc to text) and ncgen (to make text back to .nc).
2) Study the surface data before you change it and this will be your guidance. You probably need to make sure that gridcell sums add to 100% and not change anything other than the pfts.
3) I think that the clm does not use elevation data except related to the glacier model (TOPO_GLC_MEC). If you need to read in a new variable, add it to the surface data and modify the clm code to read it. We do not provide guidance on this unless you find it in the cesm/clm documentation.
4) I'm sorry, I do not know the answer because I've never worked with topo in the clm. Seems like topo is used in downscaleMod.F90 and other places in the code. Maybe it's all 0 because it's not active in your simulation. Maybe it's used only in specific cases (such as glc? downscaling?). You'll have to explore this further yourself and this could be a good exercise for becoming more familiar with the clm code.
B.
Sam:
C.
The source erodibility factor S and fz, factor depend on surface roughness are set to 1 as place holder.
Will you complete them?
In the DUSTMod.F90, line 275, you wrote that " the following comes from subr. frc_thr_rgh_fct_get". But where is "subr. frc_thr_rgh_fct_get". Does it exist?
Sam:
Lot of thanks to Sam!
Weichun Tao
A.
I want to use high resolution surface data in CLM4: the MODIS PFT data and high resolution DEM data.
For doing this I used the CLM tools to get grid, fraction, domain, surface dataset at wanted resolution.
Then I need to replace the percent PFT value in the surface data by the MODIS PFT data. And add in the elevation value.
Some questions:
1) Should I use this PFT and DEM as raw data when making surface data?
If yes, how to edit them to the format as the raw data which is accepted by the tool? Where can I get some guidence?
2) If I could only replace the PFT value after the surface data is generated, how to do it? Except the percentage of number of PFT, what else should be replaced accordingly? If I keep all other variables as default, will there be any problems?
3) Which variable in surface data is reprecentative the elevation? It seems there is only the TOPO_GLC_MEC is related to elevation. How can I add the DEM data as input to CLM? Does any guidence exist?
For doing this I used the CLM tools to get grid, fraction, domain, surface dataset at wanted resolution.
Then I need to replace the percent PFT value in the surface data by the MODIS PFT data. And add in the elevation value.
Some questions:
1) Should I use this PFT and DEM as raw data when making surface data?
If yes, how to edit them to the format as the raw data which is accepted by the tool? Where can I get some guidence?
2) If I could only replace the PFT value after the surface data is generated, how to do it? Except the percentage of number of PFT, what else should be replaced accordingly? If I keep all other variables as default, will there be any problems?
3) Which variable in surface data is reprecentative the elevation? It seems there is only the TOPO_GLC_MEC is related to elevation. How can I add the DEM data as input to CLM? Does any guidence exist?
Sam:
1) It's your choice. You do not have to modify the raw data. You could just modify the surface data. To modify any of these files, you need a method that can read, change, and write a netcdf file. This could be a fortran program, or matlab, idl, ncl, netcdf operators, the tools ncdump (to make .nc to text) and ncgen (to make text back to .nc).
2) Study the surface data before you change it and this will be your guidance. You probably need to make sure that gridcell sums add to 100% and not change anything other than the pfts.
3) I think that the clm does not use elevation data except related to the glacier model (TOPO_GLC_MEC). If you need to read in a new variable, add it to the surface data and modify the clm code to read it. We do not provide guidance on this unless you find it in the cesm/clm documentation.
4) I'm sorry, I do not know the answer because I've never worked with topo in the clm. Seems like topo is used in downscaleMod.F90 and other places in the code. Maybe it's all 0 because it's not active in your simulation. Maybe it's used only in specific cases (such as glc? downscaling?). You'll have to explore this further yourself and this could be a good exercise for becoming more familiar with the clm code.
In the DUSTMod.F90, subroutine Dustini, it is said to compute source efficiency factor from topography. The source is from Paul Ginoux and you modifided it. But I couldn't find any variable representative topography in the subroutine.
And is the basin factor "mbl_bsn_fct" representative the source efficiency factor?
And it is set to 1 for now (line 713).
Does this mean there is no code at all for calculating this factor?
And is the basin factor "mbl_bsn_fct" representative the source efficiency factor?
And it is set to 1 for now (line 713).
Does this mean there is no code at all for calculating this factor?
Sam:
From a quick look in the code and in the clm4 technical note, your interpretation seems correct. You will find my complete description of the dust algorithm in the clm4 technical note available on the clm web-page:
http://www.cesm.ucar.edu/models/cesm1.0/clm/index.shtml
Here we refer to the mbl_bsn_fct variable as source erodibility factor.
http://www.cesm.ucar.edu/models/cesm1.0/clm/index.shtml
Here we refer to the mbl_bsn_fct variable as source erodibility factor.
C.
The source erodibility factor S and fz, factor depend on surface roughness are set to 1 as place holder.
Will you complete them?
In the DUSTMod.F90, line 275, you wrote that " the following comes from subr. frc_thr_rgh_fct_get". But where is "subr. frc_thr_rgh_fct_get". Does it exist?
Sam:
We do not have plans to develop the dust model further.
If I remember correctly what I meant by this, the comment should say "the following comes from subr. frc_thr_rgh_fct_get in Charlie Zender's dust model." You may be able to download or request Charlie Zender's dust model from his website.
If I remember correctly what I meant by this, the comment should say "the following comes from subr. frc_thr_rgh_fct_get in Charlie Zender's dust model." You may be able to download or request Charlie Zender's dust model from his website.
Lot of thanks to Sam!
Weichun Tao