Response of tropical cyclone potential intensity over the north Indian Ocean to global warming

Abstract

The responses of tropical cyclone (TC) potential intensity (PI) and the associated environmental control parameters over the North Indian Ocean (NIO) to the doubled CO2 concentration are assessed based on the ensemble simulation from 15 coupled general circulation models (CGCMs) participated in the Intergovernmental Panel for Climate Change (IPCC) Forth Assessment Report (AR4). The results show that the annual mean sea surface temperature (SST) averaged over the NIO increases 1.71°C. The thermodynamic efficiency changes little because the outflow layer temperature increases accordingly. The monthly mean vertical shear decreases across the NIO with a maximum decrease of 8% in May-June except for a small increase in April. The dynamic efficiency decreases to the north of 10°N over Bay of Bengal while increases significantly in the southern NIO in response to the doubled CO2 concentration. The PI increases by 4.6% and 5.9% averaged over Arabian Sea and 2.0% and 4.86% averaged over Bay of Bengal during TC and summer monsoon seasons, respectively. An important finding is the significant increase in PI in May when the background PI is already high and the potentially longer TC season in response to global warming due to the decrease in vertical shear in June and September. Copyright 2009 by the American Geophysical Union.