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Asymmetric Estuarine Responses to Changes in River Forcing: A Consequence of Nonlinear Salt Flux

Asymmetric Estuarine Responses to Changes in River Forcing: A Consequence of Nonlinear Salt Flux A linear theory for estuarine adjustment to river forcing as put forth by MacCready is extended to allow for quantification of nonlinear salt flux induced by gravitational exchange flow. It has been shown that, under a steplike change of river forcing, the estuarine responses are asymmetric, with the salinity field adjusting faster during the rising discharge. The asymmetry arises because the up-estuary salt flux due to exchange flow is a nonlinear function of estuarine length ∝ L −3 . During the rising discharge, the estuary is longer, and the salt flux is comparatively less sensitive to the length variations. As a result, the up-estuary salt transport cannot keep pace with the rate of discharge changes, leading to a larger net salt flux and thus a shorter response time. A simple theory accounting for the nonlinear effect is then applied to Hudson-like systems and shown to capture the asymmetric response. The asymmetry is generalizable to other estuarine regimes where up-estuary salt fluxes are expressed as nonlinear power laws. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Physical Oceanography American Meteorological Society

Asymmetric Estuarine Responses to Changes in River Forcing: A Consequence of Nonlinear Salt Flux

Journal of Physical Oceanography , Volume 45 (11) – May 12, 2015

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References (17)

Publisher
American Meteorological Society
Copyright
Copyright © 2015 American Meteorological Society
ISSN
0022-3670
eISSN
1520-0485
DOI
10.1175/JPO-D-15-0085.1
Publisher site
See Article on Publisher Site

Abstract

A linear theory for estuarine adjustment to river forcing as put forth by MacCready is extended to allow for quantification of nonlinear salt flux induced by gravitational exchange flow. It has been shown that, under a steplike change of river forcing, the estuarine responses are asymmetric, with the salinity field adjusting faster during the rising discharge. The asymmetry arises because the up-estuary salt flux due to exchange flow is a nonlinear function of estuarine length ∝ L −3 . During the rising discharge, the estuary is longer, and the salt flux is comparatively less sensitive to the length variations. As a result, the up-estuary salt transport cannot keep pace with the rate of discharge changes, leading to a larger net salt flux and thus a shorter response time. A simple theory accounting for the nonlinear effect is then applied to Hudson-like systems and shown to capture the asymmetric response. The asymmetry is generalizable to other estuarine regimes where up-estuary salt fluxes are expressed as nonlinear power laws.

Journal

Journal of Physical OceanographyAmerican Meteorological Society

Published: May 12, 2015

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