Monitoring ecological dynamics in Africa with the ERS-1 scatterometer

Radar backscatter measurements obtained over Africa by the C-band scatterometer aboard the First European Remote Sensing Satellite (ERS-1) are analyzed for the period from November 1991 to December 1994. The predominant signal in this time series is the annual variation of the normalized radar cross section (NRCS) in the savanna regions north and south of the tropical rain forest. The change in the incidence angle dependence of the NRCS as well as the increase in radar cross section correlates well with the precipitation rate and indicates an instantaneous onset of vegetation growth during the rainy season. In particular the exceptional high rain rates in 1994 as well as the drought in 1991/92 in southern Africa are well reflected in the NRCS data.