PRECIPITATION RECYCLING IN THE AMAZON BASIN

Precipitation recycling is the contribution of evaporation within a re gion to precipitation in that same region. The recycling rate is a dia gnostic measure of the potential for interactions between land surface hydrology and regional climate. In this paper we present a model for describing the seasonal and spatial variability of the recycling proce ss. The precipitation recycling ratio, rho, is the basic variable in d escribing the recycling process. Rho is the fraction of precipitation at a certain location and time which is contributed by evaporation wit hin the region under study. The recycling model is applied in studying the hydrologic cycle in the Amazon basin. It is estimated that about 25% of all the rain that falls in the Amazon basin is contributed by e vaporation within the basin. This estimate is based on analysis of a d ata set supplied by the European Centre for Medium-range Weather Forec asts. The same analysis is repeated using a different data set from th e Geophysical Fluid Dynamics Laboratory. Based on this data set, the r ecycling ratio is estimated to be 35%. The seasonal variability of the recycling ratio is small compared with the yearly average. The new es timates of the recycling ratio are compared with results of previous s tudies, and the differences are explained.