Publication Date:
2022-05-25
Description:
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C10014, doi:10.1029/2008JC004750.
Description:
The combined effect of cooling and wind-driven buoyancy flux (WDBF) on a buoyant coastal current east of Cape Cod is investigated using observations and process-oriented numerical modeling. Theoretical considerations show that with the moderately strong surface density gradients observed in the Outer Cape Cod Coastal Current, WDBF can substantially exceed the buoyancy loss due to cooling, especially during intense winter storms. Evidence of deep convection associated with strong negative WDBF during downwelling-favorable winds is clearly seen in the moored observations. A simplified two-dimensional numerical model is used to illustrate the evolution of wind- and buoyancy-driven cross-shelf overturning circulation in response to surface cooling and episodic storm events. The simulation confirms that WDBF plays an important role in driving subduction of cold surface water at the offshore surface outcrop of the coastal current font. The presence of the coastal current is also shown to block onshore Ekman transport. As a result, the downwelling circulation in a cross-shore plane is predicted to have a complex multicell structure, in which exchange between the inner shelf and midshelf is restricted. The downwelling circulation has a major impact on the cross-shelf origin of cold, dense shelf waters contributing to intermediate layers of the Wilkinson Basin of the Gulf of Maine.
Description:
This work was supported by the Coastal
Ocean Institute of the Woods Hole Oceanographic Institution and the
WHOI SeaGrant Office under grant NA06OAR4170021. G.G. was supported
by the Office of Naval Research as part of the AWACS program
under grant N00014-05-1-0410. A.S. was supported, in part, by WHOI
Post-Doctoral Scholarship.
Keywords:
Coastal current
;
Wind-driven buoyancy flux (WDBF)
;
Cooling
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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