Rainfall

Abstract

There are various techniques to retrieve rainfall from satellites, each with their own set of attributes that are dictated by the particular needs for the information; for short-term, high spatial resolution applications like flash flood forecasting, the IR methods are generally preferred, while for global, climate scales, the PMWare usually preferred. In this sense, no single approach can be defined as the best one; however, in terms of accuracy on the instantaneous time scale (i.e., at the time the satellite is making its measurement), it is generally accepted that the active MW is the most accurate, followed by passive MW (ocean), passive MW (land), IR, and VIS. Many of the early methods were developed using sensors that were not necessarily flown for rainfall retrieval but more for tracking cloud features and monitoring atmospheric temperature and moisture. As was described, more recent and near-term missions are being designed specifically for rainfall monitoring and include AMW sensors (e.g., the GPM mission). Additionally, emerging methods such as the blended techniques or multispectral (including PMW and AMW) will yield improvements to the current accuracy of the remote sensing of rainfall and will likely become the standard retrieval method as we enter into the next decade.