GEWEX Land Processes Database Map Server

GEWEX Databases


Make available consistent land processes and population spatial databases at 1—km cell size for each of the regional GEWEX site. These databases will be distributed by CD-ROM and over the Internet.

     A series of themes have been extracted for the regional sites. The criteria for the selection of the themes are that they are consistent for each of the sites and of a spatial and thematic resolution relevant for drainage basin scale studies. The 1-km databases are designed for continent or large regional studies and are not appropriate for small study areas. The themes are those that are readily available at the EROS Data Center and that appear to be most relevant for drainage basin studies.


EDC DAAC: Global 1-km AVHRR (NDVI)

February 1-10, 1995 — Jan 21-30, 1996
NDVI 10-day composites



EDC DAAC: Global Land Cover Characterization (GLCC)

Land Cover Characterization




Drainage Basins



UNEP/CIESIN: Population

Population Density



ESRI: ArcWorld 1:3M

International boundaries
Administrative boundaries



ESRI: Digital Chart of the World (DCW)

Hydrology (rivers, lakes and oceans)



Re-Analysis Data

European Centre for Medium-Range Forecasts
NASA/GSFC Global Modeling and Assimilation Office
National Centers for Environmental Prediction (NCEP)/NCAR

Other Data Sets:

Earth Observing System Data Gateway
National Geophysical Data Center
Global Change Data Center
International Soil Moisture Network
USGS Land Cover Characterization
University of Maryland Global Land Cover Facility
World Data Center for Meteorology

Map Projection:

Lambert Azimuthal Equal Area map projections with projection centers optimized for each continent were used for the regional sites. These map projections are the native projection for the HYDRO1k themes. The Global 1-km AVHRR themes are native in the Goode’s map projection and the population theme is native in geographics. These themes can readily be converted to Lambert. All of the themes with the exception of population are native at 1-km cell size.

Projection and cell size:

Projection Limitations:

Study areas cannot include the north pole, south pole or the 180° longitude. The sun angle restricts images during the winter in the far north and south. Cloud cover can restrict certain periods in the AVHRR data on all continents.


File structures:

The file structures were selected to allow the maximum information to be retained within the data structure while still providing a structure that can be used. Most analysis systems and general purpose image processing systems can read the GEOTIFF structure. The external ASCII data description files are provided for those who cannot use the geo tags in the TIFF file. Vector data is always a problem. Arc/INFO export file format was selected as the de facto transfer format that can be ingested by most image analysis systems while maintaining the information content of the vector data.

File structures:

UNEP Logo UN Logo United Nations Environment Programme
Global Resource Information Database

Division of Early Warning & Assessment - North America
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