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contributor authorLippmann, Thomas C.
contributor authorBowen, Anthony J.
date accessioned2017-06-09T17:21:59Z
date available2017-06-09T17:21:59Z
date copyright2016/12/01
date issued2016
identifier issn0022-3670
identifier otherams-83887.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4227161
description abstractield observations from a vertical stack of two-component current meters obtained from the 1994 Duck94 nearshore field experiment (presented in a companion paper by Lippmann, et al.) show significant vertical structure in energy, phase, and rotation of motions at low frequencies around 0.005 Hz. Low-frequency motions are typically modeled in the surfzone with the shallow-water (depth averaged) momentum equations that do not allow for any vertical structure. Following work from the shelf tidal community (Prandle), this study shows that the observations are consistent with the depth-varying momentum equations including shear stresses induced by a bottom boundary layer described by a constant eddy viscosity ?t and bottom friction given by a constant drag coefficient and depth-averaged velocity . The bidirectional flow field is solved over arbitrary depth profiles varying only in the cross-shore direction h(x) in the presence of a vertically uniform mean alongshore current with cross-shore shear structure V(x). Analytic solutions are found to depend on ?t, cd, h, ?V/?x, and the parameter , where σ and k are the radian frequency and alongshore wavenumber of the oscillating motion. Model behavior is explored by plotting solutions for a given parameter space as functions of the nondimensional depth H = ?h and dimensionless friction parameter that combines the effects of bottom drag and vertical mixing. The behavioral changes in amplitude, phase shift, and rotational structure over the water column are qualitatively similar to those observed in the field.
publisherAmerican Meteorological Society
titleThe Vertical Structure of Low-Frequency Motions in the Nearshore. Part II: Theory
typeJournal Paper
journal volume46
journal issue12
journal titleJournal of Physical Oceanography
identifier doi10.1175/JPO-D-16-0015.1
journal fristpage3713
journal lastpage3727
treeJournal of Physical Oceanography:;2016:;Volume( 046 ):;issue: 012
contenttypeFulltext


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