Systematic Ground-Based Measurements of Mesospherc Water Vapor and Radio Wave Absorption

Ground-based microwave radiometry has been used to remotely measure mesospheric water vapor during the late winter and spring of 1983-1984 and through the winter of 1984 and spring of 1985. The 22.235-GHz spectral emission line has been observed with a cryogenically cooled MASER low-noise receiver. A simple measure of the emission feature is obtained by fitting a best fit exponential to each spectra. During the same time interval, an "A3" radio wave absorption experiment monitored D-region ionospheric radio absorption. A comparison is made of the observed water vapor spectral height and area to the observed radio wave absorption. During active sun conditions (1983-1984) radio wave absorption seems uncorrelated to the water vapor. However, during quiet sun conditions, some general agreement between the spectral area and radio wave absorption is observed. Long term variations of 2 to 1 in the water vapor spectral height are found.