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Title: Wind-Forced Seasonal Exchange between Marginal Seas and the Open Ocean

The circulation within marginal seas subject to periodic winds, and their exchange with the open ocean, are explored using idealized numerical models and theory. This is motivated by the strong seasonal cycle in winds over the Nordic Seas and the exchange with the subpolar North Atlantic Ocean through the Denmark Strait and Faroe Bank Channel. Two distinct regimes are identified: an interior with closedf/hcontours and a shallow shelf region that connects to the open ocean. The interior develops a strong oscillating along-topography circulation with weaker ageostrophic radial flows. The relative importance of the bottom Ekman layer and interior ageostrophic flows depends only onωh/Cd, whereωis the forcing frequency,his the bottom depth, andCdis a linear bottom drag coefficient. The dynamics on the shelf are controlled by the frictional decay of coastal waves over an along-shelf scaleLy=f0LsHs/Cd, wheref0is the Coriolis parameter, andLsandHsare the shelf width and depth. ForLymuch less than the perimeter of the basin, the surface Ekman transport is provided primarily by overturning within the marginal sea and there is little exchange with the open ocean. ForLyon the order of the basin perimeter or larger, most of the Ekman transport is provided from outside the marginal sea with an opposite exchange through the deep part of the strait. This demonstrates a direct connection between the dynamics of coastal waves on the shelf and the exchange of deep waters through the strait, some of which is derived from below sill depth.

Significance Statement

The purpose of this study is to understand how winds over marginal seas, which are semienclosed bodies of water around the perimeter of ocean basins, can force an exchange of water, heat, salt, and other tracers through narrow straits between the marginal sea and the open ocean. Understanding this exchange is important because marginal seas are often regions of net heat, freshwater, and carbon exchange with the atmosphere. The present results identify a direct connection between processes along the coast of the marginal sea and the flow of waters through deep straits into the open ocean.

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Award ID(s):
1922538 1947290 2218309
Author(s) / Creator(s):
Publisher / Repository:
Journal of Physical Oceanography
Date Published:
Journal Name:
Journal of Physical Oceanography
Page Range / eLocation ID:
763 to 777
Medium: X
Sponsoring Org:
National Science Foundation
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