Impacts of Wave-Current Interactions on Storm Surge during the Passage of Hurricane Ian (2022): An Application of the UFS-Coastal Modeling Framework

Hurricane Ian moved northwestward through the Caribbean Sea. Upon entering the Gulf of Mexico, it landed in southwest Florida on September 28, 2022, with peak marine winds reaching up to 72 m/s (161 mph). Storm surge heights exceeded 2.1 m in Fort Myers and approximately 4 m in Fort Myers Beach. After traversing central Florida, it returned offshore into the Atlantic and made its final landfall in South Carolina. Hurricane Ian was classified as a Category 5 Atlantic hurricane, resulting in significant wind damage and flooding, becoming one of the most costly natural disasters on record.

A workflow based on the Unified Forecast System-Coastal Application (UFS-Coastal) framework was developed and applied to simulate and analyze coastal ocean responses to Hurricane Ian using the cloud platform Parallel Works. Firstly, the OCSMesh tool (https://github.com/noaa-ocs-modeling/OCSMesh) was used to subset and combine the 34-knot wind coverage region with high-resolution grids and other areas with coarse mesh on the Eastern Coast of the United States domain. The final mesh included approximately 2.4 million grids with resolutions ranging from 5 m to 2.1 km. Secondly, the ocean components, WAVEWATCH III (WW3), and the 2-dimensional Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM), including river runoffs coupled with the National Water Model (NWM), were forced with atmospheric data (ATM) through the Community Data Models for Earth Prediction Systems (CDEPS) to generate surge simulations for Hurricane Ian. The simulation sets, including ATM+SCHISM, and ATM+SCHISM+WW3, were employed to explore the impact of wave-current interactions on storm surge simulations. Finally, the simulation results were compared with observations (NOAA CO-OPS stations using Searvey https://github.com/oceanmodeling/searvey) for sea level, high water marks, significant wave heights, etc. Standard statistical measures were utilized to validate the performance of the coupled system and identify spatial and temporal limitations. The simulation results for Hurricane Ian demonstrate the wave’s impacts on storm surge and the predictive capabilities of UFS-Coastal in forecasting total water levels, wave heights, and flood inundation regions.