Variability of Shelfbreak Currents North of Cape Hatteras

Glen Gawarkiewicz1, Frank Bahr2, Brian Hogue3, Magdalena Andres4, Robert E Todd2, Harvey Seim5, Sara Haines6, John Bane7, Mike Muglia8, Catherine Richardson Edwards9 and Dana K Savidge10, (1)Woods Hole Oceanographic Institution, Woods Hole, MA, United States, (2)Woods Hole Oceanographic Institution, Physical Oceanography, Woods Hole, MA, United States, (3)Woods Hole Oceanographic Institution, United States, (4)WHOI, Woods Hole, United States, (5)University of North Carolina at Chapel Hill, Earth, Marine, and Environmental Sciences, Chapel Hill, NC, United States, (6)University of North Carolina at Chapel Hill, Earth, Marine, and Environmental Sciences, Chapel Hill, United States, (7)University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, (8)Coastal Studies Institute North Carolina, United States, (9)Skidaway Institute of Oceanogr, Savannah, GA, United States, (10)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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