Monthly fractional green vegetation cover associated with land cover classes of the conterminous USA

The land cover classes developed under the coordination of the International Geosphere-Biosphere Programme Data and Information System (IGBP-DIS) have been analyzed for a study area that includes the Conterminous United States and portions of Mexico and Canada. The 1-km resolution data have been analyzed to produce a gridded data set that includes within each 20-km grid cell: 1) the three most dominant land cover classes, 2) the fractional area associated with each of the three dominant classes, and 3) the fractional area covered by water. Additionally, the monthly fraction of green vegetation cover (fgreen) associated with each of the three dominant land cover classes per grid cell was derived from a 5year climatology of 1-km resolution NOAA-AVHRR data. The variables derived in this study provide a potential improvement values derived as an average for the grid cell. The advantages of sub-grid cell vegetation information have been discussed by Koster and Suarez [1992] and demonstrated by Avissar and Pielke [1989] as well as others. The objectives of this study included development of land surface data sets for use in coupled land-atmosphere models that include sub-grid cell land classes and the seasonal characteristics of vegetation (fgreen) associated with each of those land classes for the Conterminous USA. A grid cell size of 20 km by 20 km was selected for this initial analysis as this is the nominal grid cell size in the current operational Eta model at NCEP