Revisiting the Future Projections of Tropical Cyclones Intensity

The varying atmospheric and oceanic states impact the tropical cyclone intensity on both short-term weather time scales and long-term climate time scales. In a warming climate, the changes of environmental conditions of the atmosphere and ocean are not uniform and it is complicated to estimate the net influence on tropical cyclones. This study adopts the recently improved Dynamic Potential Intensity (DPI) which applies the depth averaged temperature and involves the subsurface salinity-induced stratification information. By using the Simple Ocean Data Assimilation reanalysis, and the IBTrACS (International Best Track Archive for Climate Stewardship) tropical cyclone best track data, a minimum DPI threshold is established for the intensification of TCs into category five hurricanes or typhoons in different regions of global tropical cyclones. The projected changes in accordance with the established minimum threshold under the CMIP5 RCP 4.5 and 8.5 scenarios are further analyzed using the ensemble DPI mean from CMIP5 models. The role of salinity is estimated. Results suggest that the depth averaged temperature which includes the effect of salinity stratification will continue to rise attributed to greenhouse gas emissions (GHG). However, the projected atmosphere condition in the future largely compensates for the influences of ocean temperature increases on the intensity of tropical cyclones.