MST radar observations of short‐period gravity wave during overhead tropical cyclone

Abstract

Short‐period gravity waves associated with the passage of tropical cyclone using mesosphere‐stratosphere‐troposphere (MST) radar located at Gadanki (13.5°N, 79.2°E) has been discussed. The observed stratospheric gravity wave is found to have a periodicity of ∼42 min, vertical and horizontal wavelength of ∼3.5 km and 14 km, respectively. Maximum amplitude of gravity wave is observed in the upper troposphere and lower stratosphere (UTLS) region due to which periodic updrafts and downdrafts are observed. This weakens the stability of tropopause, which is observed in radar signal‐to‐noise ratio (SNR). The enhancement of vertical momentum flux of order ∼−0.6 m 2 /s 2 observed in the lower stratosphere is attributed to the cyclone generated gravity waves. The obstacle effect is found to be the generative mechanism for the observed gravity waves associated with the tropical cyclone.