National Oceanic and
Atmospheric Administration
United States Department of Commerce


 

FY 2010

Idealized two-dimensional modeling of a coastal buoyancy front, or river plume, under downwelling-favorable wind forcing with application to the Alaska Coastal Current

Williams, W.J., T.J. Weingartner, and A.J. Hermann

J. Phys. Oceanogr., 40(2), 279–294, doi: 10.1175/2009JPO4206.1 (2010)


The cross-shelf structure of a buoyancy-driven coastal current, such as produced by a river plume, is modeled in a two-dimensional cross-shelf slice as a "wide" geostrophically balanced buoyancy front. Downwelling-favorable wind stress applied to this front leads to advection in the surface and bottom boundary layers that causes the front to become steeper so that it eventually reaches a steep quasi-steady state. This final state is either convecting, stable and steady, or stable and oscillatory depending on D/delta(*) and b(y)/f(2), where D is bottom depth, delta(*) is an Ekman depth, b(y) is the cross-shelf buoyancy gradient, and f is the Coriolis parameter. Descriptions of the cross-shelf circulation patterns are given and a scaling is presented for the isopycnal slope. The results potentially apply to the Alaska Coastal Current, which experiences strong, persistent downwelling-favorable wind stress during winter, but also likely have application to river plumes subjected to downwelling-favorable wind stress.



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