Land Data Assimilation Schemes (LDAS): Parameters

Land Surface Parameters

GLDAS Vegetation Parameter Illustrations

This page illustrates the GLDAS unified land/water mask used in the GLDAS simulations. Details of the construction of the GLDAS unified mask are similar to that given in NLDAS described here.

In order to create the land/sea masks on this page, the percent coverage of water in each GLDAS grid box was used such that grid boxes made up of more than 50% water were assigned a "water" value of 0 in the GLDAS land/sea mask, while all other grid boxes recieved a "land" value of 1.

GLDAS Unified Mask
GLDAS land water mask, land in black, water in white

GLDAS Unified Land/Sea Mask

GLDAS Unified Land/Sea Mask (Ascii) UMD60mask0.25.asc
This ascii file contains the GLDAS unified land/sea mask in the following format:

Column 1	Grid Column Number
Column 2	Grid Row Number
Column 3	Latitude
Column 4	Longitude
Column 5	Mask Value (0=Water, 1=Land)

GLDAS UMD Dataset

GLDAS runs its 1-D land surface models on vegetation-based tiles to simulate variability below the scale of the model grid squares. A tile is not tied to a specific location within the grid square. Instead, each tile represents the area covered by a given vegetation type. The maximum number of tiles per grid square is determined by the user. A 1 km global vegetation dataset which uses the University of Maryland classification scheme is the basis for designating tile space. The predominant vegetation type in each 1/4 grid square is shown below.

GLDAS predominant vegetation type for each 1/4 grid box. There are 13 types of vegetation covering categories such as forests, woodlands, grassland, and cropland. The plot shows extensive areas of broadleaf forest in South America, cropland across parts of central US, shrubland across the American southwest and Australia, and decisuous forest in eastern US and northern Asia.

GLDAS predominant vegetation type for each 1/4 grid box. There are 13 types of vegetation covering categories such as forests, woodlands, grassland, and cropland. The plot shows extensive areas of broadleaf forest in South America, cropland across parts of central US, shrubland across the American southwest and Australia, and decisuous forest in eastern US and northern Asia.

UMD Vegetation Dataset used in GLDAS

The GLDAS Dominant Vegetation Type datasets are available at 1/4 degree and 1 degree. Files are in binary format (big_endian) and can be read using Fortran (1/4 degree f90 code, 1 degree f90 code) or GrADS (1/4 degree GrADS Control File, 1 degree GrADS Control File).

Frequency of Occurrence of UMD Vegetation Types (Ascii) UMD_60G0.25.txt
This ascii file lists the frequency with which each of the 14 UMD vegetation types occurs in each of the 1/4 degree LDAS grid boxes. The file is formatted as follows:

Column 1	Grid Column Number
Column 2	Grid Row Number
Column 3	Latitude
Column 4	Longitude
Column 5	Total Number of 1km Pixels in each 1/4 Degree Grid Box
Column 6	Frequency of Water (And Goode's Interrupted Space) (Category 0)
Column 7	Frequency of Evergreen Needleleaf Forest(Category 1)
Column 8	Frequency of Evergreen Broadleaf Forest (Category 2)
Column 9	Frequency of Deciduous Needleleaf Forest (Category 3)
Column 10	Frequency of Deciduous Broadleaf Forest (Category 4)
Column 11	Frequency of Mixed Cover (Category 5)
Column 12	Frequency of Woodland (Category 6)
Column 13	Frequency of Wooded Grassland (Category 7)
Column 14	Frequency of Closed Shrubland (Category 8)
Column 15	Frequency of Open Shrubland (Category 9)
Column 16	Frequency of Grassland (Category 10)
Column 17	Frequency of Cropland (Category 11)
Column 18	Frequency of Bare Ground (Category 12)
Column 19	Frequency of Urban and Built-Up (Category 13)

GLDAS Fractional Vegetation Cover

In many instances the predominant vegetation type in a given grid square does not cover 100% of the area so that a significant area of the grid contains bare soil. Shown below is the global fractional vegetation cover used in GLDAS.

$GLDAS Fractional vegetation cover for each 1/4 grid box. The plot shows that most of the eastern US, South America, Europe, and northern Asia have greater than 90% fractional vegetation cover. In the dry areas of northern Africa, the percentage is under 20%.$ Fractional Vegetation Cover Dataset used in GLDAS

LDAS Web Page
Developed and Maintained at NASA/GSFC

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