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The front on the Northern Flank of Georges Bank in spring : 2. Cross-frontal fluxes and mixing

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Field Value
Title The front on the Northern Flank of Georges Bank in spring : 2. Cross-frontal fluxes and mixing
Names Ullman, David S. (creator)
Dale, Andrew C. (creator)
Hebert, Dave (creator)
Barth, John A. (creator)
Date Issued 2003 (iso8601)
Note copyrighted by American Geophysical Union
Abstract Hydrographic observations made with an undulating vehicle carrying a CTD and
concurrent shipboard ADCP velocity observations over a 12-day period are combined to
investigate vertical mixing and cross-frontal fluxes on the Northern Flank of Georges
Bank. The CTD density time series is analyzed to detect the presence of vertical overturns,
the statistics of which are used to infer vertical mixing parameters. Vertical turbulent
buoyancy fluxes are downward and most intense, reaching values of 5 x 10¯⁷ W/kg, near
the bottom at the edge of the bank and decrease both on- and off-bank. Horizontal, crossbank
buoyancy fluxes are partitioned into mean, tidal pumping, and nontidal eddy
components and are computed as a function of cross-isobath/vertical position by averaging
in the along-isobath direction. The tidal pumping component is dominant over most of the
cross-bank section with a peak value of ~1 x 10¯⁴ W/kg, directed off-bank near the bank
edge. A diagnosed tidal vertical velocity field is used with mean buoyancy gradients to
compute the along-isopycnal skew flux. The horizontal component of this skew flux has
similar spatial structure and magnitude to that of the observed tidal pumping flux. The
divergent component of the skew flux, at depths above the bottom boundary layer, appears
to be convergent north of the bank edge and divergent at the bank edge, suggesting that
tidally driven advective processes drive buoyant bank water downward and off-bank at
mid-depth and force the upwelling of deep, dense water near the bottom at the bank edge.
Genre Article
Identifier Ullman, D. S., Dale, A. C., Hebert, D. and Barth, J. A., 2003, The front on the Northern Flank of Georges Bank in spring: 2. Cross-frontal fluxes and mixing: J. Geophys. Res., v. 108(C11), 8010.

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