DROUGHT MONITORING AND CORN YIELD ESTIMATION IN SOUTHERN AFRICA FROM AVHRR DATA

Drought is one of the major environmental disasters in southern Africa . In recent years, the damage from droughts to the environment and eco nomies of some countries was extensive, and the death toll of livestoc k and wildlife was unprecedented. Weather data often come from a very sparse meteorological network, incomplete and/or not always available in good time to enable relatively accurate and timely large scale drou ght detection and monitoring. Therefore, data obtained from the Advanc ed Very High Resolution Radiometer (AVHRR) sensor on board the NOAA po lar-orbiting satellites have been studied as a tool for drought monito ring and climate impact assessment in southern Africa. The AVHRR-based vegetation condition index (VCI) and temperature condition index (TCI ) developed recently were used in this study because in other parts of the globe they showed goon results when used for drought detection an d tracking, monitoring excessive soil wetness, assessment of weather i mpacts on vegetation, and evaluation of vegetation health and producti vity. The results clearly show that temporal and spatial characteristi cs of drought in southern Africa can be detected, tracked, and mapped by the VCI and TCI indices. These results were numerically validated b y in situ data such as precipitation, atmospheric anomaly fields, and agricultural crop yield. In the later case, it lans found that usable corn yield scenarios can be constructed from the VCI and TCI at approx imately 6 (in some regions up to 13) weeks prior to harvest time. Thes e indices can be especially beneficial when used together with ground data. (C) Elsevier Science Inc., 1998.