Determination of Rainfall with the ESOC Precipitation Index

Abstract

A validation of the ESOC (European Space 0Perations Centre) Precipitation Index (EPI) is carried out by comparing satellite data with observed rainfall in five African countries to determine the ability of estimating accumulated precipitation independently of the area considered. In the formulation of the EPI it is assumed that most of the tropical rain originates from deep and cold clouds. The scheme is a cloud indexing method based on the infrared channel, additionally including a stratification of data into three classes according to the Upper Tropospheric Humidity (UTH) obtained from METEOSAT 6.3 ?m channel. The results indicate that rainfall can be well estimated in the tropical area while more sophisticated methods are required for the subtropics. The stratification of the data according to the UTH constitutes an improvement which is particularly significant away from the Intertropical Convergence Zone (ITCZ).