Ocean heat content for tropical cyclone intensity forecasting and its impact on storm surge

Abstract

Accurate tropical cyclone track and intensity forecasts are vital to storm surge prediction and risk management. However, current cyclone intensity forecast skill is deficient, especially for rapid, unexpected intensification events. These sudden intensification events could be catastrophic if they occur just prior to making landfall in heavily populated and storm surge-vulnerable regions of the world. New satellite altimetry observations have revealed that oceanic subsurface warm features such as eddies and currents could make a critical contribution to the sudden intensification of high-impact cyclones. These warm features are characterized by high ocean heat content or tropical cyclone heat potential (TCHP) and can effectively limit a cyclone’s self-induced negative feedback from ocean cooling to favor intensification. This manuscript presents recent advancements in the understanding of the ocean’s role in generating intense tropical cyclones, that can produce high storm surge events such as Hurricane Katrina (2005) and ‘killer’ Cyclone Nargis (2008), which produced high storm surge events. Regional characteristics and on-going cyclone intensity forecast and storm-surge modeling efforts are also described. Quantitative assessment based on the case of Hurricane Rita (2005) revealed that an encounter with a high TCHP region can lead to large difference in the subsequent surge and inundation. The results show that, after a high TCHP encounter, there is approximately a 30 % increase in surge and inundation along the coast and new areas become submerged deep inland, as compared to a tropical cyclone that does not encounter a high TCHP region along its storm track.