Increased cyclone destruction potential in the Southern Indian Ocean

Abstract

The present study examines the role of the Southern Indian Ocean (SIO) warming on the cyclone destruction potential or Power Dissipation Index (PDI) during two contrasting periods of 1980-1998 and 1999-2016. The PDI in the SIO during 1999-2016 is found to have doubled compared to the same during 1980-1998. PDI was computed using the tropical cyclone track data in the SIO region for cyclone category three and above. The increasing trend in PDI during the latter period is primarily due to an increase in the intensity of cyclones and their duration. The increasing PDI is associated with a sea surface temperature warming and an upper ocean heat content increase as well as a significant slowdown in translation speeds. The increase in upper ocean heat content during the recent decades enhances the intensification of cyclones and their duration, which is consistent with the slowdown of cyclones. Analysis of the relevant atmospheric parameters indicates that processes in the atmosphere did not play a major role in the recent decades in increasing cyclone intensity. We show that in the SIO, ocean processes play a major role in the PDI rise during the recent period. Any continued increase in PDI will cause more loss of life and socioeconomic damage to the island countries such as Mozambique, Mauritius, Mascarene Islands and Madagascar, as well as the coastal inhabitants along East Africa.