Measurement of atmospheric water vapour content over a tropical location by dual frequency microwave radiometry

Atmospheric water vapour was measured over a tropical location, Calcutta, b y deploying dual frequency microwave radiometers operating at 22.235 and 31 .4 GHz. Simultaneous measurements of brightness temperature and hence atten uation in the presence of thin cloud were made for the purpose. An algorith m was developed to exclude the effect of non-precipitating liquid water dur ing the measurement of water vapour. The experimental results are supported by the corresponding radiosonde data analysis. Dual frequency radiometric measurements are shown to improve the rms accuracy, over the single frequen cy inversion technique, for the measurement of water vapour.