Modeling Mid-Atlantic Bight Cold Pool Warming Rates

Wendell S Brown, University of Massachusetts Dartmouth, New Bedford, MA, United States and Richard P Arena, University of Massachusetts Dartmouth, Estuarine and Ocean Sciences, New Bedford, United States
Abstract:
Historically from July through September, the general warming of the Mid-Atlantic Bight (MAB) Cold Pool is about 1oC per month. During September 2013, a three-glider fleet measured the warming. We addressed the problem of what oceanic processes warm the Cold Pool in different parts of the MAB. To do so, we developed a volume-averaged model of the Cold Pool temperature. The temperature conservation model focused on the lower layer Cold Pool on a finite slice of the shelf. The volume-averaged temperature change of that slice is attributed to the (a) downward turbulent transport of temperature from the upper to the lower layer; (b) convergence/divergence of long-shelf and cross-shelf advective temperature transport; and (d) eddy temperature transport across the shelf-break front. We evaluated this model with September 2013 ocean glider measurements made in the northeastern, middle and southwestern MAB. At all three locations, the downward turbulent temperature transport from the warm upper layer was small relative to other terms. We also found that distinctly different sets of oceanic processes contributed to Cold Pool warming at the different locations. In the northeastern MAB south of New England, the onshore advective temperature transport across the Shelf-Break Front (SBF) nearly compensated the long-shelf divergence. In the middle MAB off New Jersey, the onshore eddy temperature transport across the SBF was the principal compensation for the long-shelf divergence. In the southwestern MAB off Maryland, the offshore eddy plus advective temperature transport across the SBF almost compensated for the long-shelf convergence. The estimated small warming rates of the Cold Pool was different at each of these MAB locations and consistent with the overall warming of the summer Cold Pool.