Global Land Cover Characterization (GLCC)

Global Land Cover Characterization (GLCC) is a series of global land cover classification datasets made available by the United States Geological Survey. They are based primarily on the unsupervised classification of 1-km AVHRR (Advanced Very High Resolution Radiometer) 10-day NDVI (Normalized Difference Vegetation Index ) composites. The AVHRR source imagery dates from April 1992 through March 1993. Ancillary data sources include digital elevation data, eco-regions interpretation, and country- or regional-level vegetation and land cover maps. Given the age of the AVHRR source imagery the derived land use/cover data may in places be outdated.

The following classifications are included in the GLCC database:

• Global Ecosystems: 99 classes

• IGBP Land Cover Classification: 17 classes

• U.S. Geological Survey Land Use/Land Cover System: 24 classes

• Simple Biosphere Model: 16 classes

• Simple Biosphere 2 Model: 11 classes

• Biosphere Atmosphere Transfer Scheme: 20 classes

• Vegetation Lifeform: 8 classes

All of the GLCC classifications consist of raster images that contain class number values for each pixel that correspond to the appropriate classification scheme legend. Legends for each of the derived datasets are listed in the appendices to the GLCC database documentation.

All GLCC data is available in two forms:

1) GLCC (by continent) provides the GLCC classifications, as well as monthly NDVI composites, on a continent-by-continent basis (Africa, North America, South America, Eurasia, and Australia/Pacific). The continent GLCC data is available in the Interrupted Goode Homolosine or in the Lambert Azimuthal Equal-Area projection. Nominal spatial resolution is 1 kilometer.

2) GLCC (global) data consists of the continent GLCC datasets which have been combined to produce a set of global GLCC composites. The global data is available in either the Interrupted Goode Homolosine or in geographic (latitude/longitude) coordinates. Nominal spatial resolution is 1 kilometer.

All datasets are available in either GeoTIFF or BIL raster format. For every GLCC dataset, there are two versions available. Version 1 consists of GLCC data which has undergone complete accuracy assessment. Version 2 is updated GLCC which reflects additional data and sources, but accuracy assessment has not been completed.