Monitoring arid lands using AVHRR-observed visible reflectance and SMMR-37 GHz polarization difference

Abstract

Previous studies have shown the usefulness of visible reflectance observed by varied space-borne sensors for monitoring arid and semi-arid regions of the world, with particular reference to desertification. Visible reflectance along a transect through the Sahel and Sudan zones of Africa has been derived from observations by the advanced very high resolution radiometer (AVHRR) on board the NOAA-7 and NOAA-9 satellites and compared with concurrent observations of the 37 GHz polarization difference by the scanning multichannel microwave radiometer (SMMR) on board the Nimbus-7 satellite. The study period was January 1982 to December 1986, which included an unprecedented drought during 1984 over the Sahel zone. While spatial and temporal patterns of these two data sets are found to be highly correlated, there are also quantitative differences which need to be understood.