Potential of combined spaceborne infrared and microwave radiometry for near real-time rainfall attenuation monitoring along earth-satellite links

The objective of this paper is to investigate how spaceborne remote sensors , and their derived products, can be exploited to optimize the performances of a satellite communication system in the presence of precipitating cloud s along the path. The complementarity between sun-synchronous microwave (MW ) and geostationary infrared (IR) radiometry for monitoring the earth's atm osphere is discussed and their potential as a rain detection system within near real-time countermeasure techniques for earth-satellite microwave link s is analysed. A general approach, consisting in estimating rainfall intens ity and attenuation by polar-orbiting microwave radiometers and temporally tracking the rainfall areas by geo-stationary infrared radiometers, is deli neated. Multiple regression algorithms for predicting rainfall attenuation from spaceborne brightness temperatures and from surface rainrate, trained by radiative transfer and cloud models, are illustrated. A maximum likeliho od technique is delineated to discriminate stratiform and convective rainfa ll from spaceborne brightness temperatures. The differences among attenuati on estimates derived from layered raining-cloud structures with respect to those obtained from simple rain stabs, as recommended by ITU-R, are also qu antified. A test of the proposed attenuation prediction methods is performe d using raingage and Italsat data acquired in Spino d'Adda (Italy) during 1 994. A description of the statistical method, based on the probability matc hing technique, adopted to combine MW and IR data for retrieving and tracki ng precipitating cloud systems in terms of path attenuation and accumulated rain at ground is finally provided together with its application to a case study over the Mediterranean area during October 1998. Copyright (C) 2001 John Wiley & Sons, Ltd.