Research Insights

Similar to the step-like improvement seen during the advent of ocean surface topography in the early 1990s, the NASA Surface Water Ocean Topography (SWOT) satellite will revolutionize oceanography by measuring large spatial regions with unprecedented detail, enabling scientists to answer previously unanswerable questions. One such long-standing question has been how meridionally connected is the shelf circulation on the Northwest Atlantic shelf? Addressing this question will simultaneously address the fate of Arctic- and Greenland-sourced meltwater that accumulates on the Newfoundland and Labrador shelf and could impact the Atlantic Meridional Overturning Circulation, as well as the predictability of ocean properties on the Northwest Atlantic Shelf that is home to one of the most productive ecosystems globally and has experienced accelerated warming in the recent decade. Previous attempts to answer this question have not been able to convincingly cover the large spatial scales of the region while simultaneously resolving its fine-scale structure. High-resolution ocean surface topography from SWOT provides the first glimpse of this entire system on its natural scales, enabling us to address the net effect of sub mesoscale features such as the coastal currents, shelfbreak jets, shelfbreak eddies, and cross-shelf streamers on the large-scale connectivity of the shelf. Here, we hypothesize that the equatorward flow over the Northwest Atlantic shelf is a leaky conduit with exchange from the shelf and open ocean that has been increasing through time. To address this hypothesis, we have structured a project around the SWOT ocean surface topography data of the Northwest Atlantic shelf spanning Davis Strait to Cape Hatteras. Our overarching goal is to answer where, when, and why shelf-basin occurs over the study region and whether the amount of this exchange has been increasing through time. We have divided the project into three components: (1) validation of the SWOT data using a wide array of in situ data collected from moorings, drifters, gliders, and ships, (2) analysis of the meridional connectivity and persistence of the shelf circulation, and (3) process studies of hypothesized hot spots of shelf-basin exchange at the retroflection of the Labrador Current, the Northeast Channel of the Gulf of Maine, the separation of the Gulf Stream from the shelf at Cape Hatteras, and time-dependent impingements of warm core rings on the Mid-Atlantic Bight shelfbreak. In each of the latter two work packages, we plan to initially examine the processes with the high-resolution SWOT data and then compare the results to the along-track and gridded sea-surface height derived from the nadir altimeters. Through this analysis, we plan to leverage the high spatial resolution of SWOT with the high-frequency temporal sampling and extended time scales of the nadir altimeters to test our hypothesis and gain a better understanding of the equatorward flow over the Northwestern Atlantic shelf. The team from the University of Georgia and the Woods Hole Oceanographic Institution (WHOI) has extensive experience in coastal oceanography on the Northwest Atlantic, including the use of remote sensing products, in situ observations, and ocean modeling

Funder: NASA

Amount: $919,630

PI: Nicholas Foukal, Franklin College of Arts and Sciences, Department of Marine Sciences