干旱区生态环境知识资源中心

Arid areas (e.g. desertification area) and high elevation areas (e.g. the Tibetan Plateau) with inhomogencous landscapes are characterized by extreme gradients in land surface properties such as wetness, roughness and temperature, which have a significant but local impact on the atmospheric boundary layer (ABL). Observation of the actual extent over these areas is essential to understand the mechanisms through which inhomogeneous land surfaces may have a significant impact on the structure and dynamics of the overlying ABL. Progress in this research area requires spatial measurements of variables such as surface hemispherical reflectance, radiometric surface temperature, Normalized Difference Vegetation Index (NDVI), Modified Soil Adjusted Vegetation Index (MSAVI), vegetation coverage, leaf area index (LAI), local aerodynamic roughness length, etc. Imaging radiometric board satellites can provide useful estimates of most of these variables. By using these variables, we can derive the distribution of land surface heat fluxes over inhomogeneous landscape. Parameterization methods to derive the regional land surface variables, vegetation variables and land surface beat fluxes over inbomogeneous landscapes by using NOAA/AVHRR data, Landsat TM data and field observations have been proposed in this study. The method was applied to the areas of the GAME/Tibet and the HEIFE.