Storm Wave Modeling in the Gulf of Mexico using nested WAVEWATCH III Model: A Case Study for Hurricane Ida (2021)

In this work, we aimed to study the storm waves generated by Hurricane Ida (2021) which made landfall along the Louisiana coast of the Gulf of Mexico basin. Hurricane Ida was classified as a category 4 (Saffir-Simpson hurricane scale) hurricane by the National Hurricane Center (NHC) and its maximum wind speed reached a peak of 130 kt (67 m/s). To study the impact of hurricane winds on waves, two different atmospheric forcing products, ECMWF's ERA5 and NOAA's HRRR wind data sets were used. The third-generation wave model WAVEWATCH III (WW3) was used to model the storm waves on a nested grid approach with three different grid resolutions. The simulations were carried out for the entire month of August 2021 and the estimated wave parameters were then compared with observed data obtained at several stations. It was intuitively observed that the results obtained through the atmospheric forcing of ERA5 and HRRR closely correlated with the observed values for non-hurricane conditions. However, during the peak wind conditions, wind fields were better represented in the HRRR model, and it also significantly improved the wave estimates. Through further spatial analyses of wind and wave fields, it was also identified that ERA5 is successful in representing the normal atmospheric conditions and is recommended to be used for studies on long-term seasonal analyses. However, during a hurricane scenario, ERA5 underestimates the wind fields and therefore, HRRR atmospheric forcing is recommended for extreme wave forecasting/modeling in coastal waters.