Vertical structure of the Hatteras and Gulf Stream fronts near Cape Hatteras, NC

Catherine Richardson Edwards, Skidaway Institute of Oceanography, UGA, Savannah, GA, United States, Harvey Seim, University of North Carolina at Chapel Hill, Earth, Marine, and Environmental Sciences, Chapel Hill, NC, United States, Dana K Savidge, Skidaway Inst Oceanography, Savannah, GA, United States, Lu Han, University of North Carolina at Chapel Hill, Marine Sciences, Chapel Hill, United States and Glen Gawarkiewicz, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Abstract:
The continental shelf near Cape Hatteras is characterized by density fronts, the boundaries between the warm and salty South Atlantic Bight (SAB) shelf water, cool and fresh Mid Atlantic Bight (MAB) shelf water, and the Gulf Stream. Data from an 18-month field program at Cape Hatteras are used to describe the vertical structure of the Hatteras Front (separating MAB and SAB shelf water) as well as the Gulf Stream front along the seaward edges of MAB and SAB shelf waters. Shelf glider data show large changes in temperature and salinity over very small horizontal scales, with significant vertical structure and periodic interleaving of up to five distinct layers in less than 30 m water depth. Glider and available shipboard data will be used to characterize differences in vertical structure of the fronts separating these water masses, taking advantage of co-located oxygen and bio-optical data to characterize the front that separates Gulf Stream and SAB shelf water masses, which are typically difficult to distinguish due to overlapping T/S characteristics. Fine-scale properties of interleaving are classified using Turner angles and other tools to estimate potential instabilities due to double-diffusion and other processes. The variability in the vertical structure and occurrences of interleaving are examined with respect to the larger scale motion of the fronts. The results are compared to data from a 2004 field program, during which similar interleaving was observed in shipboard data on the seaward flank and nose of the Hatteras Front.