An Environmental Explanation for the Recent Increase in Tropical Cyclone Intensification

Abstract

<p>Tropical cyclone (TC) rapid intensification events are responsible for intensity forecasts with the highest errors, and hurricanes that rapidly intensify cause a disproportionate amount of the fatalities and damage from TCs. According to a recent study by Bhatia et al. (2019), natural variability cannot account for the recent (1982-2009), observed increase in the highest TC intensification rates in the Atlantic Basin. These results agree well with the main conclusions of Bhatia et al. (2018), which demonstrated climate change could significantly increase TC intensification rates worldwide by the end of 21<sup>st</sup> century.</p><p>Expanding on the work of Bhatia et al. (2018, 2019), TC intensification trends are analyzed for the period 1982-2017 using two observational datasets, the International Best-Track Archive for Climate Stewardship (IBTrACS) and the Advanced Dvorak Technique-HurricaneSatellite-B1 (ADT-HURSAT). The extended observational datasets confirm significant upward trends in intensifications metrics. To explore a physical explanation for the climate change response of TC intensification, we use ERA5 reanalysis data to calculate trends in the favorability of storm environments. When evaluating environmental data, we use 6-hour increments at specific annuli around already-formed storms in order to focus on synoptic conditions unique to storm evolution and not genesis. The robust trends in a 36-year times series and corresponding evolution of storm environments corroborates a climate change fingerprint on TC intensification.</p>