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GLDAS Soil Land Surface

The basic soils information used in GLDAS was derived from the global soils dataset of Reynolds, Jackson, and Rawls [WRR2000], which is available online here. That dataset includes fractions of sand, silt, and clay, and porosity, among other fields, and it is based on the FAO Soil Map of the World linked to a global database of over 1300 soil pedons (sample cores). The spatial resolution of the Reynolds maps is 5 minutes and there are two layers: 0-30 cm and 30-100 cm. These maps were spatially resampled to simulation resolution (1/4 or 1 degree) for GLDAS, and vertically inter/extrapolated to 0-2 cm, 2-150 cm, and 150-350 cm. These depths were chosen to match the most common set of depths originally used in Mosaic.

Certain model parameters are indexed based on a soil texture class and different model uses different texture class. Therefore a routine is included in LDAS to compute texture class based on fractions of sand, silt, and clay in a given grid cell for the model's soil texture classification scheme. Currently, the top layer texture information is used in all soil layers.

In GLDAS2 products, our approach is to stay with model’s default parameter datasets as much as possible, as opposed to conforming models to use the GLDAS standard parameter datasets as done in GLDAS1. The soil texture map was used if provided by the model developer, otherwise, it was computed based on the soil fractions. 

GLDAS Soil Texture

The version of Noah model in GLDAS2 uses the FAO 16-category soil texture class. The map is a hybrid of 30-second STATSGO over CONUS and 5-minute FAO elsewhere, which is available from the NCAR RAL website.


 

  1. Sand
  2. Loamy Sand
  3. Sandy Loam
  4. Silt Loam
  5. Silt
  6. Loam
  7. Sandy Cay Loam
  8. Silty Clay Loam
  9. Clay Loam
  10. Sandy Clay
  11. Silty Clay
  12. Clay
  13. Organic Materials
  14. Water
  15. Bedrock
  16. Other

 

Soil texture used in GLDAS2/Noah

  • GLDAS2/Noah Soil Texture Data (NetCDF): 0.25 degree, 1 degree
  • GLDAS2/Noah Soil Texture Data in other format (zip file including big_endian Binary data, Fortran code to read in, and GrADS control files): 0.25 degree, 1 degree

GLDAS Fractions of Clay, Sand, & Silt

 



Soil fraction maps used in GLDAS2

  • GLDAS Fractions of clay, sand, and silt Data (NetCDF): 0.25 degree, 1 degree
  • GLDAS Fractions of caly, sand, and silt Data in other format (zip file including big_endian Binary data, Fortran code to read in, and GrADS control files): 0.25 degree, 1 degree

GLDAS Soil Porosity


Soil Porosity used in GLDAS1/Mosaic

  • FAO Porosity for top, middle, and bottom layers of MOSAIC Data (NetCDF): 0.25 degree, 1 degree
  • FAO Porosity for top, middle, and bottom layers of MOSAIC Data (zip file including big_endian Binary data, Fortran code to read in, and GrADS control files): 0.25 degree, 1 degree

 

GLDAS Soil Color

The soil color map used by CLM was interpolated from a 2 x 2.5 degree global map from the National Center for Atmospheric Research (NCAR).


Soil Color used in GLDAS1/CLM2