VHF radar observations of weak echo regions in tropical mesoscale convective systems

Abstract

A multibeam VHF radar experiment, which was carried out to explore the mesoscale convective systems over Gadanki (13.5°N, 79.2°E), is discussed. These observations revealed an interesting pattern in the height horizontal distance section of radar reflectivity. A weak echo region (WER) is observed in the height region of ∼8-14 km well above the melting layer, which is believed to be first of its kind in VHF radar observations. A single vertical velocity core of ∼7 km vertical extent with ∼10 ms-1 vertical velocity is observed and it has been noticed that the WER is forming in the peripheral region of large vertical velocities. An attempt has been made to explain the plausible mechanism responsible for the formation of WERs. Significance of present results lies in showing the capability of VHF radar to scan the convective system in vertical plane, and in providing observational evidence for existence of WER above the melting level. Copyright 2005 by the American Geophysical Union.