Introduction to Passive Microwave Retrieval Methods

Abstract

This chapter introduces the reader to the basic concepts behind the remote sensing of precipitation from passive microwave radiation. Distinctions are drawn between emission-based frameworks that work well over radiometrically cold oceans, scattering methods that work better over land, and the newer optimal estimation methods that incorporate both of these concepts as well as principles adopted from the atmospheric sounding community. The reader is introduced simultaneously to the basic spaceborne sensors, and their evolution, to show how sensors and algorithms have evolved over time, leading to the current GPM satellite concept. This chapter is not a comprehensive review of all the algorithms that have been developed. Instead, it highlights individual algorithms that represent the spectrum of algorithm being employed.