AN OVERVIEW OF HAPEX-SAHEL - A STUDY IN CLIMATE AND DESERTIFICATION

HAPEX-Sahel was an international experiment designed to provide the fi eld data needed to model the climate of the Sahel and its dependence o n land surface conditions, The design of the experiment was based on t he study of a 1 degrees square experimental domain in which there were three observational supersites. At each of these supersites detailed hydro-meteorological studies were made at subsites for each of the thr ee principal vegetation types: miller, fallow savannah and tiger bush. Remote sensing from satellite and aircraft was used to scale up from the local to the regional scale. Hydrological monitoring, from 1991 to 1993, was combined with an 8-week intensive observation period that c overed the end of the wet season and the beginning of the dry season i n 1992. The structure and content of the HAPEX-Sahel Special Issue are described and an introduction is given to the HAPEX-Sahel information system where the data are stored. (C) 1997 Elsevier Science B.V.