A new perspective on MST radar observations of stratospheric intrusions into‐troposphere associated with tropical cyclone

Abstract

This paper presents the first ever evidence of stratospheric intrusion into troposphere during the passage of tropical cyclone using mesosphere‐stratosphere‐troposphere (MST) radar located at Gadanki (13.5°N, 79.2°E). The most significant and new observation is the enhanced signal‐to‐noise ratio (SNR) of thickness ∼1 km, extended from 16–13 km, when the cyclone is located close to the radar site. Small‐scale turbulence and strong downdraft followed by weak updraft are also observed from spectral‐width and vertical velocity, respectively. Further analysis of global data shows low out‐going long wave radiation (<170 W m−2), low tropopause temperature (<191 K), enhanced potential vorticity (∼1 PVU) in the upper/middle troposphere, and low specific humidity (∼2 × 10−4 kg/kg) at 300 hPa pressure level, occurs over the radar site. These observations clearly indicate the evidence of stratospheric intrusion into troposphere during the passage of tropical cyclone. The results are presented and discussed in the light of present understanding.