On the response of extreme Tropical Cyclones to Anomalous Upper Ocean Thermal Structure

This study investigates the Rapid Intensification (RI) and Maximum Intensity (MI) of Hurricanes Wilma and Rita (2005), focusing on the impact of Sea Surface Temperature (SST), SST anomalies (SSTA), Ocean Heat Content (OHC), and the Ocean Mixed Layer Depth (OMLD) on tropical cyclone intensity and trajectory. Utilizing numerical model simulations, the research aims to quantify the ocean's influence on tropical cyclone intensity, particularly under different OHC scenarios. Additionally, the study examines how these variations influence the trajectory of tropical cyclones (TCs). By exploring these relationships, this research contributes to a better understanding of the complex interplay between oceanic conditions and tropical cyclone behavior. Numerical simulations are performed using the Weather Research and Forecasting (WRF) model coupled with a simplified 1D Ocean Model. Simulations performed include a control with initialization consistent with observations, removing the SSTA, modulating the OMLD (doubling and halving), and modulating SST initialization fields at –3, –2, –1, +1, +2, +3 Celsius. Simulations successfully reproduce the RI phase and intensity trajectory of Hurricane Wilma and Rita, with the SST variations significantly impacting both intensity and track. Preliminary results (under ideal atmospheric conditions) indicate higher OHC scenarios result in a lower northerly/easterly component of the TCs displacement. The SSTA produces an average 27% lower Central Sea Level Pressure (CSLP), a 30% difference in minimum CSLP, and a mean difference in maximum wind speed of approximately 6%. Additionally, SSTA enhances the deepening rate during the RI phase by about 47%, increases the total surface heat flux by approximately 19%, and produces a 10% increase in accumulated grid scale precipitation.