SOME STUDIES ON ATTENUATION AND ATMOSPHERIC WATER-VAPOR MEASUREMENTS IN INDIA

The rainrate distributions obtained from rapid response rain gauge mea surements over five different locations in India are presented. On the basis of simultaneous observations of rainrate measured by rain gauge s having integration times of 10 seconds and 15 minutes, a power law h as been established. Rain attenuation characteristics at 11 GHz were a nalysed and some interesting results are presented, which are also com pared with International Radio Consultative Committee and other models . Attenuations due to water vapour are deduced for a frequency range o f 1-350 GHz at elevation angles 3 degrees and 10 degrees. The attenuat ion due to water vapour at a lower elevation angle is found to increas e as the tropospheric effects become dominant. It can also be seen tha t the antenna temperature attains a peak value of about 160 K in the m onsoon months and a minimum of about 80 K during the winter. The month ly variation of antenna temperature reveals a similar variation for th e attenuation and water vapour content.