U.S. Geological Survey simulations of waves and ocean dynamics during Hurricanes Ian (2022), Idalia (2023), and Helene (2024)

The Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST v3.8; Warner and others, 2010; Warner and others, 2019) modeling system was used to simulate ocean circulation, water levels, and waves that occurred during three separate hurricanes: Hurricane Ian (2022), Hurricane Idalia (2023), and Hurricane Helene (2024). Simulations were performed with coupled and concurrent ocean and wave models simulated on a set of two refined, cascading grids. The larger oceanic scale grid (USE) covered the entire U.S. East coast and Gulf of America, and had a ~5km horizontal resolution. The second grid (GOMSAB) was a region of refinement of USE and downscaled to focus in the Gulf of America. The GOMSAB grid had a ~2km horizontal resolution to cover the west and east coasts of Florida. Several simulations were conducted for each hurricane to study the spectral characteristics of the waves, current effects on waves, and how the storm transported surface drifters based on an increasing complexity of physical processes. Results on the GOMSAB grid were analyzed to investigate coastal ocean-scale dynamics, waves, and circulation.

Surface atmospheric forcings were obtained from the Coupled Ocean/Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS-TC; Doyle and others, 2012), developed by the U.S. Naval Research Laboratory. COAMPS-TC is a non-hydrostatic, convection-permitting model. The simulation was conducted by the US Navy with a 4-km resolution storm-following nest that was periodically re-initialized using a modified Rankine wind vortex. The track and intensity were nudged to fit to the Best Track from the National Hurricane Center (NHC; Bucci and others, 2022; Cangialosi and Alaka, 2023; Hagen and others, 2024). Results included surface winds, pressure, relative humidity, and air temperature.

For Hurricane Helene (2024), simulations were performed on the USEast and GOMSAB grids for a time period from 0000hr September 24, 2024 to 0000hr on September 27, 2024 UTC.
For Hurricane Ian (2022), simulations were performed on the USEast and GOMSAB grids for a time period from 0000hr September 26, 2022 to 0000hr on October 1, 2022 UTC.
For Hurricane Idalia (2023), simulations were performed on the GOMSAB grid for a time period from 0000hr August 26, 2023 to 0000hr on August 31, 2023 UTC.

References cited:

Bucci, L., Alaka, L., Hagen, A., Delgado, S., and Beven, J., 2022, National Hurricane Center Tropical Cyclone Report AL 092022, Hurricane Ian 2022, https://www.nhc.noaa.gov/data/tcr/AL092022_Ian.pdf.

Cangialosi, J.P. and Alaka, L., 2023, National Hurricane Center Tropical Cyclone Report AL 102023, Hurricane Idalia 2023, https://www.nhc.noaa.gov/data/tcr/AL102023_Idalia.pdf.

Hagen, A.B., Cangialosi, J.P., Chenard, M., Alaka, L., and Delgado, S., 2024, National Hurricane Center Tropical Cyclone Report AL 092024, Hurricane Helene 2024, https://www.nhc.noaa.gov/data/tcr/AL092024_Helene.pdf.

Doyle, J. D., Jin, Y., Hodur, R. M., Chen, S., Jin, H., Moskaitis, J., Reinecke, A., Black, P., Cummings, J., Hendricks, E., Holt, T., Liou, C.-S, Peng, M., Reynolds, C., Sashegyi, K., Schmidt, J., and Wang, S., 2012, Real-time tropical cyclone prediction using COAMPS-TC: Advances in Geosciences, Vol. 28, pp. 15–28, https://doi.org/10.1142/9789814405683_0002.

Warner, J.C., Armstrong, B., He, R., and Zambon, J.B., 2010, Development of a coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system: Ocean Modelling, v. 35, issue 3, p. 230-244, https://doi.org/10.1016/j.ocemod.2010.07.010.

Warner, J.C., Ganju, N.K., Sherwood, C.R., Kalra, T.S., Aretxabaleta, A., He, R., Zambon, J., and Kumar, N., 2019, Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System: U.S. Geological Survey Software Release, 23 April 2019, https://doi.org/10.5066/P9NQUAOW.