Comparison of three infrared satellite techniques to estimate accumulated rainfall over the Iberian Peninsula

The potential of three infrared satellite-based techniques to estimate accumulated rainfall is tested, and the techniques are compared and contrasted. The tests are conducted in the western Mediterranean area and for the first time in the Iberian Peninsula. The well-known Arkin and the Negri-Adler-Wesley techniques are applied, as well as the Autoestimator technique, during the autumn of 1994. Because the aim of this work is to automate the process of extracting the data inferred in a large number of satellite images for as long as possible (only 4368 images have been analysed in this paper), no assisted preselection is recommended. The correlation coefficients obtained for the three methods in comparisons at specific points are near 0.6; and even better results were obtained for wide areas. The Iberian Peninsula is divided into three zones, which present different climatic characteristics. Tests conducted in the north and northwest yielded the worst results, probably due to the predominance of stratiform rain and the associated orographic effects. Tests conducted in Mediterranean coastal areas gave the best results, probably due to the convective nature of precipitation predominant in this zone. Various modifications are introduced in the methods, in order to adapt them to the target area. Copyright (C) 2003 Royal Meteorological Society.