Estimation of areal rainfall from satellite data

Abstract

For hydrological, agricultural and other raindependent activities, the estimates of the average rainfall over a catchment are very important.' Most of the methods formulated for estimating the areal average rainfall make use use of raingauges has several disadvantages which are, sometimes, not easily controlled. Due to these drawbacks, recent attempts ha~e been made to utilize remote sensing techniques in the estimation of areal rainfall. Areal estimation of rainfall from METEOSAT satellite data is the main objective of this study. 10-day and monthly total cold-cloud durations (CCD) for the months of January and February, 1987 covering _ the area within Latitudes 34°E to 400E and Longitudes 50S to 90S of S'butQ.ernTanzania, digitized corresponding to the raingauge statiction network,for three different temperature thresholds was used. These records of • -!Meteosat data were'compiled at University of Reading, U.K. Daily raingauge records from 147 stations located within the study area were used. These records were used in generating 10-day and monthly total rainfall records whrch were employed in the study as "ground truth" records. The rainfall records were obtained from the Directorate of Meteorology df Tanzania, Dar es Salaam. The study was divided into three sections. The first section deals with the relationship between the point CCDs and the surface recorded rainfall. Si!.ipl