Evidence of stratosphere–troposphere exchange during severe cyclones: a case study over Bay of Bengal, India

The role of cyclones in atmospheric mixing and troposphere–stratosphere exchange of ozone and relative humidity (RH) is investigated for two severe cyclones PHAILIN and HUDHUD over the Bay of Bengal. Ozone concentration from Microwave Limb Sounder along with RH profiles obtained from Sounder for Probing Vertical Profiles of Humidity instrument aboard Meghatropiques platform, upon analysis at different pressure levels, revealed a rapid increase in RH and ozone concentration from lower troposphere to upper troposphere one day prior to landfall for both cyclones. The Weather Research and Forecasting model based simulations of convergence and divergence were used to estimate mass and momentum exchanges between troposphere and stratosphere which suggest the drastic increase in RH and ozone concentrations in UT due to high convective activity. Variations in the vertical profiles of ozone and RH during cyclonic period acts as a tracer for stratosphere–troposphere exchanges during peak cyclone intensity period