From El Niño to La Niña: Vegetation Response Patterns over East and Southern Africa during the 1997–2000 Period

Abstract

Abstract During the period 1997–2000, the global climate system experienced a transition from the strongest ENSO warm event this century in 1997/98 to a strong cold event in 1999/2000. Normalized difference vegetation index (NDVI) time series data derived from the Advanced Very High Resolution Radiometer (AVHRR) instrument aboard the NOAA polar-orbiting satellite series were analyzed to resolve the land surface response patterns over Africa during this period. The rearrangement of precipitation patterns induced by the change from El Nino to La Nina conditions had significant effects on biomass production in arid and semiarid lands of Africa as revealed by NDVI anomaly patterns, particularly in equatorial East Africa and southern Africa where the ENSO–precipitation linkage is most pronounced. In general, there was a reversal in NDVI response patterns in East (southern) Africa from positive (negative) during the El Nino in 1997/98 to negative (positive) during the La Nina event in 1999/2000. These changes c...