In 1998, I moved to San Diego, and started studying cross-shore circulation on the North Carolina shelf. This research was part CoOP '94, an interdisciplinary study of the transport and distribution of planktonic larvae. My part of the project combines data analysis to describe the cross shore circulation with some simple models of larval transport.
Wind driven circulation on the North Carolina shelf resembles the coastal upwelling observed off the west coast of North America, but with some important differences. First, the North Carolina shelf is quite shallow; depths are consistent with the the inner shelf off California. Second, winds in the CoOP study area reverse weekly, and drive upwelling and downwelling circulation in rapid alternation. This contrasts with the seasonal upwelling observed on the west coast. Downwelling circulation is further complicated by the presence of the Chesapeake Bay plume, which drives a coastal jet of faster currents. By contrast, during upwelling, along-shelf currents are strongest near the upwelling front, about 10 km offshore.
Initial tests of a larval transport model based on observed currents indicate a general cross-shelf convergence over time. Passive larvae put into the model outside the surf zone tend to settle out in relatively narrow band near the upwelling and downwelling fronts. This pattern should help inner shelf benthic invertebrates remain in favorable environments, and support a healthy ecosystem.