Collaborative Research: A Lagrangian SeaSoar Study of the Coupling of Circulation, Mixing, and Productivity at a Shelfbreak Front

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0002755 HalesThe cause for the observed coincidence of enhanced biological activity in the vicinity of shelfbreak fronts will be investigated by a series of field experiments in the Middle Atlantic Bight. The hypotheses to be tested are both physical and biological. First the convergence of buoyancy flux in the bottom boundary layer drives upwelling of nutrient rich Shelf Water along the shoreward side of the shelfbreak front. Second, the biological activity is enhanced due to this large flux nutrient and by optimal optical conditions as the water transitions from turbid shelf water to clear oceanic water, making the front a region with high photosynthetic efficiency. Five new technologies (dye tracer, isopycnal floats, pumped Seasoar with high speed chemical analysis, towed microstructure instrument and use of optical variability to estimate photosynthetic properties of phytoplankton) will used in three 10-dy cruises to track the front in a Lagrangian framework.