Tidal-driven dynamics and mixing processes in a coastal ocean model with wetting and drying

Abstract

A three-dimensional sigma coordinate numerical model with wetting and drying (WAD) and a Mellor-Yamada turbulence closure scheme has been used in an idealized island configuration to evaluate how tidally driven dynamics and mixing are affected by inundation processes. Comprehensive sensitivity experiments evaluate the influence of various factors, including tidal amplitudes (from 1-to 9-m range), model grid size (from 2 to 16 km), stratification, wind, rotation, and the impact of WAD on the mixing. The dynamics of the system involves tidally driven basin-scale waves (propagating anticlockwise in the northern hemisphere) and coastally trapped waves propagating around the island in an opposite direction. The evolutions of the surface mixed layer (SML) and the bottom boundary layer (BBL) under different forcing have been studied. With small amplitude tides, wind-driven mixing dominates and the thickness of the SML increases with time, while with large-amplitude tides, tidal mixing dominates and the thickness of the BBL increases with time. The inclusion of WAD in the simulations increases bottom stress and impacts the velocities, the coastal waves, and the mixing. However, the impact of WAD is complex and non-linear. For example, WAD reduces near-coast currents during flood but increases currents during ebb as water drains from the island back to the sea. The impacts of WAD, forcing, and model parameters on the dynamics are summarized by an analysis of the vorticity balance for the different sensitivity experiments.

On the dynamics and morphology of extensive tidal mudflats: Integrating remote sensing data with an inundation model of Cook Inlet, Alaska

“…We will use the inundation model recently developed by Oey (2005Oey ( , 2006, which was based on the community Princeton Ocean Model (i.e., version POM-WAD). Oey (2005Oey ( , 2006) tested the inundation model for various 1D, 2D, and 3D idealized problems; see also Saramul and Ezer (2010) and Xue and Du (2010), for recent evaluation of the inundation processes in the model and their effect on mixing. The implementation of POM-WAD for the Cook Inlet (CI), Alaska, is described in Oey et al (2007) and Ezer et al (2008).…”