Rain attenuation measurements over New Delhi with a microwave radiometer at 11 GHz

Rain attenuation measurements over New Delhi carried out with a microwave radiometer installed at the National Physical Laboratory in that city and operating on 11 GHz for more than three years are presented. It is shown that attenuation is maximum during the monsoon period. A comparison between the attenuation distribution and rain rate demonstrates that, for 0.01 percent of the time, the attenuation value exceeded 14.0 dB, corresponding to a surface rainfall rate of 140 mm/h. For 0.1 percent of the time (monsoons of 1978, 1979), the attenuation value of 9.0 dB is seen to correspond to a surface rainfall rate of 90 mm/h. It is also shown that a single curve can represent the relation between effective distance and rate of surface rainfall for a particular site.