Temporal Patterns in Temperature, Salinity, Density, and Current Velocity from a Multi-Sensor Mooring on the Continental Slope near Cape Hatteras, N.C.

The Cape Hatteras shelf-slope region is known for a complex exchange of waters involving the Gulf Stream current as well as the convergence of Mid Atlantic Bight and South Atlantic Bight waters. Previous studies have determined patterns of variability from the shelf and slope waters using current meter moorings, shipboard acoustic Doppler current profilers (ADCP), and towed conductivity temperature depth (CTD) devices. The purpose of this study was to determine the temporal scales of variability for the entire water column in over 900 m depth due to the movement of the Gulf Stream and surrounding waters. A single bio-physical mooring with CTDs and upward and downward facing ADCPs was used to record temperature, salinity, density, and current velocity from 7 March, 2016 through 24 May, 2017 for this project. Principal component analysis and time series analysis were used to detect water column fronts through changes in temporal and vertical gradients of these variables. The current profile time series revealed multi-day to multi-week long increases and decreases in current velocity in the upper water column, with surface current velocities ranging from hundreds of mm/s to over 2 m/s depending on depth and what front events took place. This study represents the first use of a multi-sensor mooring system to determine temporal variability throughout the entire water column on the continental slope near Cape Hatteras.