Observing Gulf Stream variability near its separation point, its interactions with the Slope Sea and submesoscale variability on the adjacent shelf

The Slope Sea and the Mid-Atlantic Bight (MAB), in the NW Atlantic, are sites of strong mesoscale and submescale variability in physical and biogeochemical properties. Here, the Gulf Stream separates from the continental slope. The region is one of the more energetic oceanic environments. 

The SWOT US East Coast crossover region will observe the Gulf Stream precisely where it separates from the continental slope. The daily swath northwest of the crossover will measure the adjacent Slope Sea and the MAB, sites of strong mesoscale and submesoscale variability in physical and biogeochemical properties. 

Measurements of nutrient concentrations across sub-mesoscale features, primary productivity, and phytoplankton abundance and diversity are fundamental for understanding ecosystem dynamics in this biogeochemically complex region.

Synoptic surveys of surface and subsurface biogeochemical properties that can be linked back directly to Sea Surface Height (SSH) fields will help to constrain high resolution biogeochemical models that are being developed for the MAB.

The MAB-SWOT campaign has three main objectives: observing the Gulf Stream mesoscale (meander) and submesoscale (frontal eddy) variability; measuring the MAB shelf-break front and shelf-deep ocean exchange; assess the validity/usefulness of SWOT velocity for coastal-scale features and interpreting biophysical interactions. 

To do this, a combination of high-frequency radar, glider, current- and pressure-measuring inverted echosounder (CPIES), and ship-based biogeochemical sampling during the cal/val period are planned or proposed and will provide independent observations for comparison with SWOT altimetry.

The combination of different types of in situ observations with SWOT remote observations will provide an unprecedented depiction of mesoscale and submesoscale variability in this very dynamic region of the NW Atlantic. 

Principal investigators: Seim Harvey (UNC Chapel Hill), Sophie Clayton (ODU), Margie Mulholland (ODU), Mike Muglia (CSI), Robert Todd (WHOI), Donglai Gong (VIMS), Magdalena Andres (WHOI), Teresa Updyke (ODU), Hugh Roarty (Rutgers)

Contact point for the study site: 

Harvey Seim (, (UNC Chapel Hill)

Representative Spray glider sampling paths (orange) and proposed station-holding location (red square).
Sampling region (green box) for Slocum/Sea Explorer gliders and representative sampling paths.
Miss Caroline, ECU workboat, heading offshore.