scholarly journals The vertical structure of the bottom boundary layer on the southern flank of the George Bank during late winter

1996 ◽  
Author(s):  
Sandra R. Werner
Keyword(s):  
Boundary Layer ◽  
Vertical Structure ◽  
Bottom Boundary Layer ◽  
Late Winter ◽  
Bottom Boundary ◽  
Southern Flank

Vertical Structure of Dissipation in the Nearshore

2007 ◽  
Vol 37 (7) ◽  
pp. 1764-1777 ◽  
Author(s):  
Falk Feddersen ◽  
J. H. Trowbridge ◽  
A. J. Williams
Keyword(s):  
Boundary Layer ◽  
Wave Breaking ◽  
Vertical Structure ◽  
Vertical Shear ◽  
Bottom Boundary Layer ◽  
Breaking Wave ◽  
Vertical Diffusion ◽  
Turbulent Length Scale ◽  
Bottom Boundary ◽  
Shear Production

Abstract The vertical structure of the dissipation of turbulence kinetic energy was observed in the nearshore region (3.2-m mean water depth) with a tripod of three acoustic Doppler current meters off a sandy ocean beach. Surface and bottom boundary layer dissipation scaling concepts overlap in this region. No depth-limited wave breaking occurred at the tripod, but wind-induced whitecapping wave breaking did occur. Dissipation is maximum near the surface and minimum at middepth, with a secondary maximum near the bed. The observed dissipation does not follow a surfzone scaling, nor does it follow a “log layer” surface or bottom boundary layer scaling. At the upper two current meters, dissipation follows a modified deep-water breaking-wave scaling. Vertical shear in the mean currents is negligible and shear production magnitude is much less than dissipation, implying that the vertical diffusion of turbulence is important. The increased near-bed secondary dissipation maximum results from a decrease in the turbulent length scale.

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