Search

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° N, 76.98° 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. [ABSTRACT FROM AUTHOR]

This paper focuses on study of attenuation of microwave propagation at Ka-band frequencies due to precipitation over an Indian Tropical station, Thiruvananthapuram (8.5°N, 76.8°E). The station is located on the gateway of S-W Indian monsoon into the subcontinent characterized with prolonged rain for a period of about 9 months. A satellite link has been established at Thumba, Thiruvananthapuram, between Ka-band receiver operating at 20.2 and 30.5 GHz and GSAT-14 as part of Indian Space Research Organization's Ka-band propagation experiment. The concurrent measurements of Ka-band signals and the precipitation, using a collocated laser precipitation monitor instrument, were carried out during the entire period of Indian monsoon. The study focuses on quantifying the dependence of Ka-band attenuation on rain rate during the rain-dominated premonsoon and summer monsoon seasons. The observed attenuation has been evaluated with ITU model. [ABSTRACT FROM AUTHOR]