The 404 MHz wind profiler to observe precipitation

Abstract

This article delineates the tropical precipitation and classification of precipitating systems into stratiform and convective type, using the UHF wind profiler located at the Indian tropical station Pune (18°32′N, 73°51′E). Under moderate rain conditions the two signals arising due to clear air motions and precipita- tion are clearly distinguished in the power spectra. An algorithm with suitable methodology has been devel- oped that separates clear air and precipitation echoes when they are clearly distinguishable as seen in the power spectrum. This was tested for various power spectra and found to work well under moderate rain conditions. The sensitivity of the threshold was tested for the precipitation observed on 25 July 2005. In addition, case studies of stratiform rain (precipitation observed over the site on 26 July 2005, 0800 h IST) and convective system (a thunderstorm observed on 16 May 2004) are presented and discussed. An attempt has been made to fit a Gaussian distribution curve to determine the actual Doppler shift and spec- tral width. The observed convective and stratiform precipitation is described in terms of reflectivity, maximum spectral width and Doppler velocity gradi- ent in the vertical.