Application of the spectral wave model SWAN in Delaware Bay
Date
2005
Authors
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Publisher
University of Delaware
Abstract
SWAN (Simulating Waves Nearshore) is a third-generation numerical wave model to simulate the random, short-crested, wind-generated waves in coastal regions with shallow water and ambient currents. This study focuses on the application of SWAN in Delaware Bay. ☐ A bathymetry based on an orthogonal curvilinear grid taken from Whitney (2003), including the entire Delaware Bay and its adjacent ocean region, is used as the model domain. The grid has higher resolution in the bay than o_shore, satisfying the resolution need in shallow water and calculation e_ciency. Most of the physical processes presented in SWAN are utilized in the simulations, such as wave shoaling, refraction, nonlinear interactions, depth-induced breaking, wave-current interaction, bottom friction and whitecapping dissipation. The o_shore boundary condition is set by the wave parameters from WAVEWATCH III simulation. ☐ Two sensitivity factors in SWAN model are discussed. One is the wind _eld distribution in space. On one hand, SWAN is run with a uniform wind _eld; on the other hand, it is driven by spatially variable wind _eld. SWAN is sensitive to the current _eld as well. The current _eld calculated by ROMS (Regional Ocean Model System) with tidal input at seaward boundary has been introduced into SWAN model. ☐ Finally, three sets of _eld measurement data are used to test SWAN simulation results. First, an experiment was conducted in Delaware Bay in September 1997 to investigate acoustic uctuations and the environmental parameters. The sea surface elevation and spectrum were measured using an inverted echo sounding technique. In 2003 and 2005, a Wave Sentry Buoy (WSB) was deployed to measure the surface at the same site as experiment in 1997. The simulated current velocities from ROMS at the measuring station are compared to the ADCP data. SWAN simulations during these periods are compared to the _eld data in signi_cant wave height, dominant direction and frequency spectrum.