The Dynamics of a Partially Mixed EstuarySource: Journal of Physical Oceanography:;2000:;Volume( 030 ):;issue: 008::page 2035DOI: 10.1175/1520-0485(2000)030<2035:TDOAPM>2.0.CO;2Publisher: American Meteorological Society
Abstract: Measurements of velocity, density, and pressure gradient in the lower Hudson River estuary were used to quantify the dominant terms in the momentum equation and to characterize their variations at tidal and spring?neap timescales. The vertical momentum flux (assumed to be due mainly to turbulent shear stress) was estimated indirectly, based on the residual from the acceleration and pressure gradient terms. The indirect estimates of stress compared favorably to bottom stress estimates using a quadratic drag law, supporting the hypothesis that the tidal momentum equation involves a local balance between tidal acceleration, pressure gradient, and stress divergence. Estimates of eddy viscosity indicated that there was significant tidal asymmetry, with flood tide values exceeding ebb values by a factor of 2. As a consequence of the asymmetry, the vertical structure of the tidally averaged stress bore no resemblance to the tidally averaged shear. In spite of the asymmetry of vertical mixing, the tidally averaged, estuarine circulation was found to depend simply on the intensity of bottom turbulence, which could be parameterized by a Rayleigh drag formulation based on the tidal velocity magnitude and the tidally averaged near-bottom flow. This seemingly paradoxical result indicates that the estuarine circulation can be modeled without detailed knowledge of the effective eddy viscosity, only requiring an estimate of the bottom drag coefficient, the tidal forcing conditions, and the baroclinic pressure gradient. A notable characteristic of this solution is an inverse dependence of the estuarine circulation on the amplitude of the tides.
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contributor author | Geyer, W. Rockwell | |
contributor author | Trowbridge, John H. | |
contributor author | Bowen, Melissa M. | |
date accessioned | 2017-06-09T14:54:09Z | |
date available | 2017-06-09T14:54:09Z | |
date copyright | 2000/08/01 | |
date issued | 2000 | |
identifier issn | 0022-3670 | |
identifier other | ams-29297.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4166508 | |
description abstract | Measurements of velocity, density, and pressure gradient in the lower Hudson River estuary were used to quantify the dominant terms in the momentum equation and to characterize their variations at tidal and spring?neap timescales. The vertical momentum flux (assumed to be due mainly to turbulent shear stress) was estimated indirectly, based on the residual from the acceleration and pressure gradient terms. The indirect estimates of stress compared favorably to bottom stress estimates using a quadratic drag law, supporting the hypothesis that the tidal momentum equation involves a local balance between tidal acceleration, pressure gradient, and stress divergence. Estimates of eddy viscosity indicated that there was significant tidal asymmetry, with flood tide values exceeding ebb values by a factor of 2. As a consequence of the asymmetry, the vertical structure of the tidally averaged stress bore no resemblance to the tidally averaged shear. In spite of the asymmetry of vertical mixing, the tidally averaged, estuarine circulation was found to depend simply on the intensity of bottom turbulence, which could be parameterized by a Rayleigh drag formulation based on the tidal velocity magnitude and the tidally averaged near-bottom flow. This seemingly paradoxical result indicates that the estuarine circulation can be modeled without detailed knowledge of the effective eddy viscosity, only requiring an estimate of the bottom drag coefficient, the tidal forcing conditions, and the baroclinic pressure gradient. A notable characteristic of this solution is an inverse dependence of the estuarine circulation on the amplitude of the tides. | |
publisher | American Meteorological Society | |
title | The Dynamics of a Partially Mixed Estuary | |
type | Journal Paper | |
journal volume | 30 | |
journal issue | 8 | |
journal title | Journal of Physical Oceanography | |
identifier doi | 10.1175/1520-0485(2000)030<2035:TDOAPM>2.0.CO;2 | |
journal fristpage | 2035 | |
journal lastpage | 2048 | |
tree | Journal of Physical Oceanography:;2000:;Volume( 030 ):;issue: 008 | |
contenttype | Fulltext |