Yongnian Zeng, Nanping Xiang, Zhao dong Feng, Huo Hu
Normalized Difference Vegetation Index (NDVI) and land surface albedo are very important biophysical parameters of land surface. In this paper we analyzed quantitatively the relationship between the severity of desertification and vegetation index (NDVI) and albedo. Through experiment and theoretical reasoning, we proposed a conception of Albedo-NDVI space and discussed its biophysical characteristics. Then, we analyzed the locations of different land cover classes and the trajectory of desertification in the Albedo-NDVI space. This knowledge can be used to improve current strategies for desertification mapping and change monitoring, by defining measurements in this feature space. Therefore, we present a methodology to monitor severity of desertification. Desertification field data, available data in the literature, and ancillary data were linked with land cover characteristics (vegetation index, land surface albedo) derived from Landsat ETM+ multispectral image. The desertification synthetic index, desertification difference index (DDI), was produced, which combined information contained in the Albedo-NDVI space. This synthesis index is easy to use and possess biophysical properties of the land surface. We proposed this synthesis index as powerful one for desertification assessment.