Variability of Shelfbreak Currents North of Cape Hatteras

Glen Gawarkiewicz, Woods Hole Oceanographic Institution, Woods Hole, MA, United States, Frank Bahr, Woods Hole Oceanographic Institution, Woods Hole, United States, Brian Hogue, Woods Hole Oceanographic Institution, United States, Magdalena Andres, WHOI, Woods Hole, United States, Robert E Todd, Woods Hole Oceanographic Institution, Physical Oceanography, Woods Hole, MA, United States, Harvey Seim, University of North Carolina at Chapel Hill, Earth, Marine, and Environmental Sciences, Chapel Hill, NC, United States, Sara Haines, University of North Carolina at Chapel Hill, Earth, Marine, and Environmental Sciences, Chapel Hill, United States, John Bane, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, Mike Muglia, Coastal Studies Institute North Carolina, United States, Catherine Richardson Edwards, Skidaway Institute of Oceanogr, Savannah, GA, United States and Dana K Savidge, Skidaway Inst Oceanography, Savannah, GA, United States
Abstract:
The Shelfbreak Front in the Middle Atlantic Bight extends from Georges Bank southward to Cape Hatteras, where it deflects offshore and is entrained into the Gulf Stream. The flow just north of Cape Hatteras is particularly complicated as convergent shelf flows, Gulf Stream and Hatteras Front motions, and wind forcing affect the flow at the shelfbreak. Three bottom-mounted Acoustic Doppler Current Profilers were deployed for 18 months at the 100 m isobath north of Cape Hatteras as part of the Processes driving Exchange At Cape Hatteras (PEACH) multi-institutional study. The flow is southward in the mean, but is strongly pulsed with time scales consistent with wind forcing. The strongest pulse in 2018 occurred in March, with a maximum velocity approaching 0.8 m/s. Near the Gulf Stream separation point, where the continental slope shifts orientation to the north, there is a significant eastward component to the velocity, with maximum velocities exceeding 0.5 m/s. Temperature at the bottom (100 m) varies from 8-16 Deg. C with cooler waters associated with southward velocity pulses. Salinity at the bottom varies from 33 to 35.5 PSU. The influence of storm events as well as the impacts of significant freshening from August to October 2018 will be discussed.
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