Dynamics of the direct intrusion of Gulf Stream ring water onto the Mid-Atlantic Bight shelf

• Published in: Geophysical research letters Vol. 42; no. 18; pp. 7687 - 7695
• Main Authors: Zhang, Weifeng G., Gawarkiewicz, Glen G.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 28-09-2015; John Wiley & Sons, Inc
• Subjects: Arrays; Biogeochemistry; Circulation; Computer simulation; cross-shelf exchange; Dynamics; Entrainment; Exchanging; Fisheries; Geophysics; Gulf Stream; Impingement; Intrusion; Isobaths; Marine; Marine ecology; Mathematical models; Mid-Atlantic Bight; Migration; Migrations; Migratory species; Mineral nutrients; Nose; Numerical simulations; Nutrient transport; Ocean bottom; Ocean currents; Offshore; onshore intrusion; OOI Pioneer Array; Rivers; Satellite observation; Satellites; Shelf dynamics; Shelves; Slope water; Slopes; Transport; Vorticity; vorticity dynamics; warm-core ring; Water; Water circulation; ANW, USA, Mid-Atlantic Bight; A, Atlantic, Gulf Stream
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL065530

Onshore intrusions of offshore waters onto the Mid‐Atlantic Bight shelf can greatly affect shelf circulation, biogeochemistry, and fisheries. Previous studies have concentrated on onshore intrusions of slope water. Here we present a direct intrusion of Gulf Stream warm‐core ring water onto the shelf representing a previously unknown exchange process at the shelfbreak. Impingement of warm‐core rings at the shelfbreak generates along‐isobath intrusions that grow like Pinocchio's nose, extending hundreds of kilometers to the southwest. By combining satellite and Ocean Observatory Initiative Pioneer Array data and idealized numerical simulations, we discover that the intrusion results from topographically induced vorticity variation of the ring water, rather than from entrainment of the shelfbreak frontal jet. This intrusion of the Gulf Stream ring water has important biogeochemical implications and could facilitate migration of marine species across the shelfbreak barrier and transport low‐nutrient surface Gulf Stream ring water to the otherwise productive shelfbreak region.
Key Points
Satellite and OOI Pioneer Array data show ring water intruding onto the shelf
The intrusions extend southwestward along the shelf edge over large distances
Vortex squashing of the ring flow by the rising seafloor drives the intrusion