Principles of Surface-based Microwave and Millimeter wave Radiometric Remote Sensing of the Troposphere

Surface-based radiometric measurements of tropospheric parameters have long provided useful measurements of temperature, water vapor, and cloud liquid. In this paper, a general overview of physical fundamentals, measurement techniques, and retrieval methodology is given. Then several contemporary instruments are discussed and representative results are presented. Recent and promising developments include multifrequency radiometers, scanning observations of clouds, and combined activepassive remote sensing. The primary applications of these new technologies are weather forecasting and climate, communications, geodesy and long-baseline interferometry, satellite data validation, air-sea interaction, and fundamental molecular physics. The work presented here updates and extends the reviews published in [11] and [37].