Attenuation Characteristics of GSAT-14/Ka-Band Signals Over the Tropical Coastal Region

Collocated and concurrent measurements of the attenuation in the GSAT-14 Ka-band transponder signals at 20.2 and 30.5 GHz by using cross-polarization Ka-band beacon receiver, atmospheric and cloud parameters by using microwave radiometer profiler, and rain parameters using microrain radar and laser precipitation monitor are carried out during the prolonged Indian monsoon and the tropical convective rain events over the tropical coastal station, Trivandrum (8.5 degrees N, 76.98 degrees E), located in the Indian peninsular region. The attenuations of 10-25 and 2-12 dB, respectively, observed during the convective and the stratiform rain events. The altitudinal variability of the water vapor (relative humidity) and cloud liquid water (CLW) content during rainy conditions indicated an enhanced band of CLW in the 4-5 km altitude level during the stratiform rain and an increase in CLW throughout the column for convective rain. The effect of rain rate and raindrop size for stratiform and convective rains to the attenuation of Ka-band signals has been examined, and empirical relations between attenuation in Ka-band signal at 20.2 and 30.5 GHz and the reflectivity have been formulated for this location, which has application in the estimation of attenuation for reflectivity values measured by radars.