Land Data Assimilation Schemes (LDAS): Parameters

Land Surface Parameters

GLDAS Soil Parameter Illustrations

The basic soils information used in GLDAS was derived from the global soils dataset of Reynolds, Jackson, and Rawls [1999, WRR2000], which is available online at http://www.ngdc.noaa.gov/seg/eco/cdroms/reynolds/reynolds/reynolds.htm. 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 mainly were chosen to match the most common set of depths originally used in Mosaic. Certain model parameters are indexed based on USDA soil 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. Currently, the top layer texture information is used in all soil layers. 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).

GLDAS Soil Porosity
GLDAS soil porosity for each 1/4 grid box in the 0-2 centimeter depth range. The scale ranges from 0.35 to 0.65. The highest values of porosity are located across Canada in the boreal forests and northern Europe and Asia. The lowest values are across Australia and parts of central Asia and the middle east.

GLDAS soil porosity for each 1/4 grid box in the 0-2 centimeter depth range. The scale ranges from 0.35 to 0.65. The highest values of porosity are located across Canada in the boreal forests and northern Europe and Asia. The lowest values are across Australia and parts of central Asia and the middle east.

Soil Porosity used in GLDAS

GLDAS Soil Texture
GLDAS soil texture for each 1/4 grid box from the USDA. There are 11 classes.

Soil texture used in GLDAS

GLDAS Soil Color
GLDAS soil color (used by CLM) for each 1/4 grid box. There are eight classes.

Soil Color used in GLDAS

GLDAS Fraction of Silt
$The fraction of silt for each 1/4 grid box in the 0-2 centimeter depth range. The scale ranges from 0.1 to 0.9. The highest fraction of silt is located across northeastern Asia with values from 0.4 to 0.8. The remainder of the world has values generally ranging from 0.2-0.4.$ Fraction of Silt used in GLDAS
Fraction Silt Binary Datafiles: 1/4 degree, 1 degree Fortran code to read data: 1/4 degree, 1 degree GrADS Control Files: 1/4 degree, 1 degree

GLDAS Fraction of Clay
$The fraction of clay for each 1/4 grid box in the 0-2 centimeter depth range. The scale ranges from 0.1 to 0.9. The majority of the world has values ranging from 0.1 to 0.4. Parts of eastern South America and Africa, central Asia, and India have higher values ranging from 0.4-0.6.$ Fraction of Clay used in GLDAS
Fraction Clay Binary Datafiles: 1/4 degree, 1 degree Fortran code to read data: 1/4 degree, 1 degree GrADS Control Files: 1/4 degree, 1 degree

GLDAS Fraction of Sand
$The fraction of sand for each 1/4 grid box in the 0-2 centimeter depth range. The scale ranges from 0.1 to 0.9. Large areas in Africa, Australia, western Asia, and northern North America have values ranging from 0.6-0.9. The majority of the world has values ranging from 0.3-0.6 while the lowest values are located in northeastern Asia with values ranging between 0.2-0.3.$ Fraction of Sand used in GLDAS
Fraction Sand Binary Datafiles: 1/4 degree, 1 degree Fortran code to read data: 1/4 degree, 1 degree GrADS Control Files: 1/4 degree, 1 degree

LDAS Web Page
Developed and Maintained at NASA/GSFC

Brian Cosgrove: Brian.Cosgrove@gsfc.nasa.gov
Matthew Rodell: Matthew.Rodell-at-nasa.gov