A review of surface-based microwave and millimeter-wave radiometric remote sensing of the troposphere

Surface-based radiometric sensing of tropospheric parameters has a long history of providing useful measurements of temperature, water vapor, and cloud liquid. In this review, a general overview of physical fundamentals, measurement techniques, and retrieval methodology is given. Several contemporary instruments are then discussed and representative results are presented. Recent and promising developments include multi-frequency radiometers, scanning observations of clouds, and combined active-passive 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.