2002 Annual

Thursday, 17 January 2002: 3:30 PM
Improving the representation of arid regions of northern Africa and the Arabian peninsula in climate models by incorporating MODIS derived surface albedo
Elena Tsvetsinskaya, Boston University, Boston, MA; and C. Schaaf, F. Gao, A. Strahler, R. E. Dickinson, and X. Zeng
We use the MODerate resolution Imaging Spectroradiometer (MODIS) on board of the Terra satellite to derive surface albedo of arid areas of Northern Africa and Arabian peninsula. We discuss the spatial and temporal variability patterns of surface albedo over the period of MODIS operation. We suggest a classification scheme for the region that links various soil types and landforms to MODIS-derived albedo statistics. Work is ongoing on incorporating our results into the National Center for Atmospheric Research Common Land Model (NCAR CLM).

MODIS derived surface albedo is a sixteen-day composite analyzed at a 1km x 1km spatial resolution. We used seven MODIS spectral bands for land and three broad bands (for shortwave, NIR, and visible portions of the spectrum). Considerable spatial variability of surface albedo in the study region is observed by airborne spectroradiometers that is related to soil and geological characteristics of the surface (vegetation contribution to surface reflectance is essentially negligible in the study area since fractional canopy cover rarely exceeds 10 percent). The observed spatial variability in surface reflectance / albedo is not captured by the current version of the NCAR CLM, which uses soil color and texture to infer surface reflective properties. We suggest a scheme that relates soil groups (based on Food and Agriculture Organization, FAO, soil classification) and landforms (based on the United States Geological Service, USGS, geological maps) to MODIS derived surface albedo statistics. This approach allows for the representation in land surface models of the observed spatial variability in surface reflective properties.

Supplementary URL: