Regarding Soil Data for AMIP Experiment

[yan Chen]

In my recent work, I have been investigating the GPP obtained from the CMIP6 AMIP experiment. However, I have encountered challenges in accurately calculating soil water availability due to the unavailability of datasets for the wilting point and field capacity. I am of the belief that these two crucial parameters could be linked to soil texture in the CESM model as an input dataset, although I have been unable to locate this information online.

I am writing to inquire whether it might be feasible to access soil texture data or datasets for wilting point and field capacity specific to the CMIP6 AMIP experiment from your resources. Alternatively, I would greatly appreciate any guidance or suggestions you could provide on this matter.

 

[yan Chen]

I found a dataset named mksrf_soitex.10level.c010119.nc which is percent clay and percent sand in ten soil layers. But the abscissa of the data is from 0 to 6997 and I don't know the meaning of the numbers. The ordinate of the data is the soil layer from 0-9. I don't know if this is a global data set, if so, how to find the soil texture in the United States?

 

[slevis]

We refer to the files prefixed mksrf_ as "raw" datasets. We use them as inputs when generating CTSM's fsurdat files (surface datasets). If you "ncdump" the mksrf_soitex file, you will find out the meaning of the dimensions, and you may wish to pursue that approach further.

Alternatively, CTSM's fsurdat files contain PCT_SAND, PCT_CLAY variables in the more intuitive dimensions of nlevsoi, lsmlat, lsmon.

 

[yan Chen]

We refer to the files prefixed mksrf_ as "raw" datasets. We use them as inputs when generating CTSM's fsurdat files (surface datasets). If you "ncdump" the mksrf_soitex file, you will find out the meaning of the dimensions, and you may wish to pursue that approach further.

Alternatively, CTSM's fsurdat files contain PCT_SAND, PCT_CLAY variables in the more intuitive dimensions of nlevsoi, lsmlat, lsmon.

Thank you for reply and great suggestions!
I am inquiring about the soil depth information used in the generation of the Community Terrestrial Systems Model (CTSM) fsurdat files. Specifically, I'm interested in the contents of the file named surface-data.amip366clm2.nc, which includes surface dataset variables such as PCT_SAND and PCT_CLAY. I am seeking clarification on whether the values for PCT_SAND and PCT_CLAY represent the total percentages across all 10 soil layers or if they pertain solely to the first soil layer.

 

[slevis]

If you "ncdump" your file, you will probably see something like this:

netcdf surfdata_1.9x2.5_78pfts_CMIP6_simyr1850_c170824 {
dimensions:
        lsmlon = 144 ;
        lsmlat = 96 ;
        nglcec = 10 ;
        nglcecp1 = 11 ;
        numurbl = 3 ;
        nlevurb = 5 ;
        numrad = 2 ;
        nchar = 256 ;
        nlevsoi = 10 ;
        time = UNLIMITED ; // (12 currently)
        lsmpft = 79 ;
        natpft = 15 ;
        cft = 64 ;
variables:
        int mxsoil_color ;
                mxsoil_color:long_name = "maximum numbers of soil colors" ;
                mxsoil_color:units = "unitless" ;
        int SOIL_COLOR(lsmlat, lsmlon) ;
                SOIL_COLOR:long_name = "soil color" ;
                SOIL_COLOR:units = "unitless" ;
        double PCT_SAND(nlevsoi, lsmlat, lsmlon) ;
                PCT_SAND:long_name = "percent sand" ;
                PCT_SAND:units = "unitless" ;
        double PCT_CLAY(nlevsoi, lsmlat, lsmlon) ;
                PCT_CLAY:long_name = "percent clay" ;
                PCT_CLAY:units = "unitless" ;
        double ORGANIC(nlevsoi, lsmlat, lsmlon) ;
                ORGANIC:long_name = "organic matter density at soil levels" ;
                ORGANIC:units = "kg/m3 (assumed carbon content 0.58 gC per gOM)" ;
        double FMAX(lsmlat, lsmlon) ;
                FMAX:long_name = "maximum fractional saturated area" ;
                FMAX:units = "unitless" ;

As you can see, PCT_SAND and PCT_CLAY are values in each soil layer. From these values you can also come up with PCT_SILT as follows:

PCT_SILT = 100 - PCT_SAND - PCT_CLAY

 

[yan Chen]

If you "ncdump" your file, you will probably see something like this:

netcdf surfdata_1.9x2.5_78pfts_CMIP6_simyr1850_c170824 {
dimensions:
        lsmlon = 144 ;
        lsmlat = 96 ;
        nglcec = 10 ;
        nglcecp1 = 11 ;
        numurbl = 3 ;
        nlevurb = 5 ;
        numrad = 2 ;
        nchar = 256 ;
        nlevsoi = 10 ;
        time = UNLIMITED ; // (12 currently)
        lsmpft = 79 ;
        natpft = 15 ;
        cft = 64 ;
variables:
        int mxsoil_color ;
                mxsoil_color:long_name = "maximum numbers of soil colors" ;
                mxsoil_color:units = "unitless" ;
        int SOIL_COLOR(lsmlat, lsmlon) ;
                SOIL_COLOR:long_name = "soil color" ;
                SOIL_COLOR:units = "unitless" ;
        double PCT_SAND(nlevsoi, lsmlat, lsmlon) ;
                PCT_SAND:long_name = "percent sand" ;
                PCT_SAND:units = "unitless" ;
        double PCT_CLAY(nlevsoi, lsmlat, lsmlon) ;
                PCT_CLAY:long_name = "percent clay" ;
                PCT_CLAY:units = "unitless" ;
        double ORGANIC(nlevsoi, lsmlat, lsmlon) ;
                ORGANIC:long_name = "organic matter density at soil levels" ;
                ORGANIC:units = "kg/m3 (assumed carbon content 0.58 gC per gOM)" ;
        double FMAX(lsmlat, lsmlon) ;
                FMAX:long_name = "maximum fractional saturated area" ;
                FMAX:units = "unitless" ;

As you can see, PCT_SAND and PCT_CLAY are values in each soil layer. From these values you can also come up with PCT_SILT as follows:

PCT_SILT = 100 - PCT_SAND - PCT_CLAY

Thank you for providing clarification! I realize now that I had a misunderstanding.