Nested-grid Circulation Model Research Articles

Examination of circulation, dispersion, and connectivity in Lunenburg Bay of Nova Scotia using a nested-grid circulation model

A coastal ocean observatory has been established in Lunenburg Bay, Nova Scotia since summer 2002 as part of a multi-agency research program of marine environmental observation and prediction over Atlantic Canada coastal waters. The observatory was operational when a category-2 hurricane (Juan) made land fall within 50-km of the bay in September 2003. The coastal response of the bay to Hurricane Juan is examined using a nested-grid coastal circulation modelling system. The nested-grid system is forced by the local wind, tides, and remotely generated coastal waves. A comparison of model results with observed surface elevations and currents demonstrates that the nested-grid system has reasonable skills in simulating the three-dimensional (3D) storm-induced circulation in the study region. The 3D model currents are used to examine the transport and dispersion of passive tracers, local flushing time, and retention and connectivity of passive particles in the bay during Hurricane Juan. Numerical results demonstrate that local wind forcing plays a dominant role in generating large dispersion and hydrodynamic connectivity in the bay during the storm.

Modelling of Suspended Sediment Transport in Coastal Areas Under Waves and Currents

A coupled hydrodynamic/suspended sediment transport model including waves and currents was developed. Four models, a nested grid circulation model (2-D and 3-D), a refraction-diffraction-dissipation wave propagation model, a wave-current bottom boundary layer model and a quasi-3-D suspended sediment concentration (SSC) model are integrated. The model system has been applied to Cleveland Bay, Australia to study SSC in January and March 1993 when two high SSC events (>100mg l−1) were observed during an intensive field monitoring programme. The swell has been found to be the dominant suspension mechanism and thus an important factor of high SSC in the bay. The model was able to predict the high SSC events in January and March 1993. A net deposition rate in Cleveland Bay was estimated to be about 0·1mm year−1, a figure consistent with geological evidence.