MST radar observation of inertia-gravity waves generated from tropical cyclones

Using a Mesosphere Stratosphere Troposphere (MST) radar, operating at 53 MHz at Gadanki (13.5°N, 79.2°E), India, the present study reports on the temporal and spatial characteristics of inertia-gravity waves (IGWs) generated from four tropical cyclones that formed over the Bay of Bengal. IGWs are observed with intrinsic frequencies, vertical and horizontal wavelengths in the ranges of 1.2f–3.0f, 2.5–5, and 300–1600 km, respectively, where f is the Coriolis frequency at the Gadanki site. It is found that both the convective and geostrophic adjustment processes in the troposphere play a major role in the generation of IGWs. Also it is found that the horizontal propagation direction of IGWs is aligned along the motion of convective rain bands.

► We examine the MST radar observation of cyclones generated inertia-gravity waves.
► These four Bay of Bengal cyclones: TC03B, FANOOS, KHAI_MUK and NISHA are considered.
► Lower atmospheric winds during these four cyclones show cyclonic structures.
► Hodograph analysis of the inertia-gravity waves tracks the movement of cyclones.
► The inertia-gravity waves propagate normal outward from the cyclones as expected.