Experimental Determination of Water Vapor Profiles from Ground-Based Radiometer Measurements at 21.0 and 31.4 GHz.

Abstract

Water vapor profiles have been obtained from radiometer measurements at 21.0 and 31.4 GHz and ground values of humidity, temperature and pressure. The inversion technique was based on minimum variance estimation, including constraints derived from a statistical ensemble of radiosonde measurements. Corrections were included to give profiles under cloudy conditions with a resulting accuracy comparable with clear-sky situations. The comparison between the retrieved profiles and radiosonde measurements shows good agreement. The rms difference is 0.8 g m?3 at altitudes lower than 2 km, decreasing to 0.2 g m?3 at 6 km. This is a somewhat higher accuracy than what has been obtained in earlier experiments.