A high-resolution 3-D circulation model in a complex archipelago on the coastal Scotian Shelf

A high-resolution coastal Finite-Volume Community Ocean Model (FVCOM) has been configured to simulate the water circulation in the Eastern Shore Islands (ESI) archipelago on the coastal Scotian Shelf. Circulation in this area is characterized by complex interactions between the irregular coastline, a dense archipelago, tides, wind, and subtidal currents.  Model outputs show close agreement with the tides, subtidal current and hydrographic observations. Two circulation regimes within the study area were identified ‘inshore’ and ‘offshore’ of the 60-m isobath. The balance between pressure gradient and Coriolis effect controls the dominant southwestward current (Nova Scotia Current) in the offshore. Rotary spectra and numerical experiments showed that the tidal current was an important component to the circulation in the inshore. Within the study area there are several clockwise and counter-clockwise gyres related to the Coriolis effect, surface wind stress, pressure gradient and the interaction between the irregular topography and current. The combined effects of topography, wind, tide and Nova Scotia Current regulate the inshore circulation. The topographic features complex the cross-shore transport. The increased bathymetric slope and strengthened relative vorticity contribute to the inshore cross-shore current. Here, we found that the joint effect of baroclinicity and bottom relief drives the cross-isobath transport. The ability of our model to resolve complex coastal circulation patterns provides an important basis on which to better understand how physical oceanography influences the unique ecological processes of this coastal archipelago and ultimately will help to evaluate dispersal and connectivity of coastal species in this area.