| Description |
The Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST v3.8; Warner and others, 2019; Warner and others, 2010) modeling system was used to simulate ocean circulation, water levels, and waves that occurred during Hurricane Dorian (2019) along the US East coast. Simulations were then further downscaled to focus on the resulting inundation, dune overtopping, and barrier island breaching during the storm along North Core Banks, NC. Simulations were performed with coupled and concurrent ocean and wave models simulated on a series of refined, cascading grids. The largest scale grids covered the entire US east coast (5km resolution), and subsequent grids downscaled to the Carolinas region (700m resolution), then to Pamlico Sound (250m resolution). Results on these grids were analyzed to investigate bay-scale dynamics of oceanic conditions. Results were further used to drive a coastal scale grid that stretched approximately 1.5 km in the alongshore and 4km in the cross-shore directions to cover a region of several breaches along North Core Banks. This nearshore grid had cross-shore resolution that varied from 10 m to 2m across the barrier island and was 1.5m in the alongshore direction. Several simulations on this smallest scale grid were performed to investigate sediment grain size (coarse and fine) and effects of vegetation included or excluded yes vegetation and no vegetation) on the breaching processes.
Surface atmospheric forcings were obtained from the NOAA Rapid Refresh v4 (Dowell and others; https://rapidrefresh.noaa.gov/) atmospheric analysis and included surface winds, pressure, relative humidity, and air temperature at ~13 km spatial resolution. For the smallest grid, four simulations were performed: coarse sediment and yes vegetation (CSYV), coarse sediment no vegetation (CSNV), fine sediment and yes vegetation (FSYV), and fine sediment no vegetation (FSNV). The sediment on the seafloor was initialized with a uniform 10m thick distribution. The coarse sediment had an erosion rate of 0.050 kg/m2/s; mean grain size of 0.40 mm, settling velocity of 47 mm/s, and a 0.22 N/m2 critical threshold of erosion. The fine sediment had an erosion rate of 0.025 kg/m2/s; mean grain size of 0.25 mm, settling velocity of 27 mm/s, and a 0.19 N/m2 critical threshold of erosion.
Reference cited:
Dowell, D. C., Alexander, C.R., James, E.P., Weygandt, S.S., Benjamin, S.G., Manikin, G.S., Blake, B.T., Brown, J.M., Olson, J.B., Hu, M., Smirnova, T.G., Ladwig, T., Kenyon, J.S., Ahmadov, R., Turner, D.D., Duda, J.D., and Alcott, T.I., 2022, The High-Resolution Rapid Refresh (HRRR): An Hourly Updating Convection-Allowing Forecast Model. Part I: Motivation and System Description: Wea. Forecasting, 37, 1371–1395, https://doi.org/10.1175/WAF-D-21-0151.1.
Warner, J.C., Armstrong, Brandy, He, Ruoying, 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.
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.
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