Cyclone Induced Changes in the Ocean and Atmosphere in the north Indian Ocean

Tropical cyclones in the north Indian Ocean evolve differently in response to the SST changes during the pre-monsoon (April-June) and post-monsoon (October-December) cyclone season. It is observed that during the pre-monsoon season, cyclone induced SST cooling is significantly larger than the post-monsoon cyclones. Also, the maximum cooling is observed 2-3 days after the passage of the cyclone. This difference in the SST response is mainly due to the different ocean subsurface dynamics and difference in the cyclone translation speed during the two seasons. The recovery time of the cyclone induced SST cooling in pre-monsoon season is more than two weeks, which is larger than the post-monsoon season. Further, the pre-monsoon cyclones induce large mid-to-upper tropospheric warming, of the magnitude of up to 3 ºC, in both the basins. This cyclone induced atmospheric warming is relatively low in the post-monsoon cyclone season. This difference in the atmospheric warming induced by the cyclones in the two seasons is linked to the difference in the cyclone-ocean interactions during the two seasons.