Ocean surface waves in Hurricane Ike (2008) and Superstorm Sandy (2012): Coupled model predictions and observations

Abstract

Forecasting hurricane impacts of extreme winds and flooding requires accurate prediction of hurricane structure and storm-induced ocean surface waves days in advance. The waves are complex, especially near landfall when the hurricane winds and water depth varies significantly and the surface waves refract, shoal and dissipate. In this study, we examine the spatial structure, magnitude, and directional spectrum of hurricane-induced ocean waves using a high resolution, fully coupled atmosphere-wave-ocean model and observations. The coupled model predictions of ocean surface waves in Hurricane Ike (2008) over the Gulf of Mexico and Superstorm Sandy (2012) in the northeastern Atlantic and coastal region are evaluated with the NDBC buoy and satellite altimeter observations. Although there are characteristics that are general to ocean waves in both hurricanes as documented in previous studies, wave fields in Ike and Sandy possess unique properties due mostly to the distinct wind fields and coastal bathymetry in the two storms. Several processes are found to significantly modulate hurricane surface waves near landfall. First, the phase speed and group velocities decrease as the waves become shorter and steeper in shallow water, effectively increasing surface roughness and wind stress. Second, the bottom-induced refraction acts to turn the waves toward the coast, increasing the misalignment between the wind and waves. Third, as the hurricane translates over land, the left side of the storm center is characterized by offshore winds over very short fetch, which opposes incoming swell. Landfalling hurricanes produce broader wave spectra overall than that of the open ocean. The front-left quadrant is most complex, where the combination of windsea, swell propagating against the wind, increasing wind-wave stress, and interaction with the coastal topography requires a fully coupled model to meet these challenges in hurricane wave and surge prediction.

Wind‐Based Estimations of Ocean Surface Currents From Massive Clusters of Drifters in the Gulf of Mexico

“…We use highly realistic winds and waves from a coupled ocean‐atmosphere‐wave model to implement the parameterization for V cor and V W . The source for the synoptic wind and wave data used in this study is the UWIN‐CM (Chen & Curcic, ; Chen et al, ). It is designed as a multimodel system with the flexibility of exchanging individual model components for the atmosphere, waves, ocean, land, and sea ice.…”

Hurricane‐induced ocean waves and stokes drift and their impacts on surface transport and dispersion in the Gulf of Mexico

“…Recent advancement in high‐resolution, fully coupled atmosphere‐wave‐ocean modeling made it possible to study the hurricane‐induced surface waves and Stokes drift. Chen and Curcic [] showed that the coupled model predictions of ocean surface waves in Hurricane Ike (2008) and Superstorm Sandy (2012) were verified very well against both in situ observations from the National Data Buoy Center buoys and the satellite observations. The coupled modeling studies by Chen et al [] and Chen and Curcic [] have shown that hurricane‐induced surface waves are highly complex and asymmetric in terms of wave heights and propagation directions around a moving storm.…”

Quantifying initial and wind forcing uncertainties in the Gulf of Mexico

“…Similarly, passive OGCM simulations where wind forcing is not affected by the ocean states should be improved to a coupled atmosphere-wave-ocean model to better simulate the dynamics across the atmosphere-ocean interface. Based on the insight provided by the present experiences, work is underway to enhance both the construction and propagation of more realistic uncertain input fields, particularly by relying on the fully coupled atmospherewave-ocean model [6]. Results from this ongoing effort will be reported in a future study.…”

“…However, due to the rapid increase in the basis size when increasing the polynomial order, the hyperbolic truncation introduced in [40] is employed in this study. Specifically, we use an isotropic polynomial basis which is the union set of three hyperbolic truncated basis given by maximum total order of No = [6,20,35]; the corresponding truncation parameters are q = [1, 0.55, 0.42], respectively. The choice of this basis has been carefully analyzed for all the approximations constructed below.…”