Land Surface Parameters

GLDAS Vegetation Class and Mask Illustrations

This page illustrates the GLDAS unified land/water mask and the land cover data used in the GLDAS simulations. GLDAS currently uses the land surface datasets from the Moderate Resolution Imaging Spectroradiometer (MODIS) as our "standard". The GLDAS version 2 products (GLDAS2) use the data described on this page. Previously, GLDAS has used the Advanced Very High Resolution Radiometer (AVHRR) based datasets, in which we refer to our "old standard". The old standard vegetation parameter datasets are used in GLDAS version 1 products (GLDAS1) and are available here.

GLDAS Land/Sea Mask Dataset

GLDAS adopted the MOD44W MODIS Water Mask as the standard land/sea mask. The mask data [Carroll et al, 2009] is produced at University of Maryland and described here. Instead of deriving the mask from a land cover data as done in GLDAS1, the standard mask is "imposed" to land cover data and other surface parameter maps in GLDAS2. In order to create the land/sea masks on this page, the percent coverage of 0.01 degree water pixels 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 received a "land" value of 1.

GLDAS land water mask, land in black, water in white
GLDAS standard Land/Sea Mask

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 high resolution MODIS land cover dataset is the basis for designating tile space. In GLDAS2, different land cover classification schemes are used depending on the land surface model.

The land cover in GLDAS2/Noah version 3.3 is based on a 30 arc second MODIS vegetation data that uses modified IGBP classification scheme (see details). The predominant vegetation type in each 1/4 grid square is shown below.

GLDAS NOAHv3.3 predominant vegetation type for each 1/4 grid box. The modified IGBP category provided by NCEP, which includes 20 types of land cover categories.
NOAHv3.3 Vegetation Dataset used in GLDAS2

The GLDAS2/Noah Dominant Vegetation Type datasets (Binary): 1/4 degree, 1 degree
Fortran code to read the Big_endian binary data: 1/4 degree, 1 degree
GrADS Control Files: 1/4 degree, 1 degree

  • Frequency of Occurrence of Modified IGBP Vegetation Types for GLDAS2/Noah (Ascii)
    This ascii file lists the frequency with which each of the 20 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 0.01 degree Pixels in each 1/4 Degree Grid Box
    Column 6 Frequency of Evergreen Needleleaf Forest (Category 1)
    Column 7 Frequency of Evergreen Broadleaf Forest(Category 2)
    Column 8 Frequency of Deciduous Needleleaf Forest (Category 3)
    Column 9 Frequency of Deciduous Broadleaf Forest (Category 4)
    Column 10 Frequency of Mixed Forest (Category 5)
    Column 11 Frequency of Closed Shrublands (Category 6)
    Column 12 Frequency of Open Shrublands (Category 7)
    Column 13 Frequency of Woody Savannas (Category 8)
    Column 14 Frequency of Savannas (Category 9)
    Column 15 Frequency of Grassland (Category 10)
    Column 16 Frequency of Permanent Wetland (Category 11)
    Column 17 Frequency of Cropland (Category 12)
    Column 18 Frequency of Urban and Built-Up (Category 13)
    Column 19 Frequency of Cropland/Natural Vegetation Mosaic (Category 14)
    Column 20 Frequency of Snow and Ice (Category 15)
    Column 21 Frequency of Barren or Sparsely Vegetated (Category 16)
    Column 22 Frequency of Ocean (Category 17)
    Column 23 Frequency of Wooded Tundra (Category 18)
    Column 24 Frequency of Mixed Tundra (Category 19)
    Column 25 Frequency of Bare Ground Tundra (Category 20)