The importance of tidal and lateral asymmetries in stratification to residual circulation in partially mixed estuaries


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dc.contributor.author Scully, Malcolm E.
dc.contributor.author Friedrichs, Carl T.
dc.date.accessioned 2010-12-02T14:34:15Z
dc.date.available 2010-12-02T14:34:15Z
dc.date.issued 2007-06
dc.identifier.citation Journal of Physical Oceanography 37 (2007): 1496-1511 en_US
dc.identifier.uri http://hdl.handle.net/1912/4149
dc.description Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 1496-1511, doi:10.1175/jpo3071.1. en_US
dc.description.abstract Measurements collected in the York River estuary, Virginia, demonstrate the important impact that tidal and lateral asymmetries in turbulent mixing have on the tidally averaged residual circulation. A reduction in turbulent mixing during the ebb phase of the tide caused by tidal straining of the axial density gradient results in increased vertical velocity shear throughout the water column during the ebb tide. In the absence of significant lateral differences in turbulent mixing, the enhanced ebb-directed transport caused by tidal straining is balanced by a reduction in the net seaward-directed barotropic pressure gradient, resulting in laterally uniform two-layer residual flow. However, the channel–shoal morphology of many drowned river valley estuaries often leads to lateral gradients in turbulent mixing. Tidal straining may then lead to tidal asymmetries in turbulent mixing near the deeper channel while the neighboring shoals remain relatively well mixed. As a result, the largest lateral asymmetries in turbulent mixing occur at the end of the ebb tide when the channel is significantly more stratified than the shoals. The reduced friction at the end of ebb delays the onset of the flood tide, increasing the duration of ebb in the channel. Conversely, over the shoal regions where stratification is more inhibited by tidal mixing, there is greater friction and the transition from ebb to flood occurs more rapidly. The resulting residual circulation is seaward over the channel and landward over the shoal. The shoal–channel segregation of this barotropically induced estuarine residual flow is opposite to that typically associated with baroclinic estuarine circulation over channel–shoal bathymetry. en_US
dc.description.sponsorship Support for this research was provided by the National Science Foundation Division of Ocean Sciences Grant OCE- 9984941. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher American Meteorological Society en_US
dc.relation.uri http://dx.doi.org/10.1175/jpo3071.1
dc.subject Tides en_US
dc.subject Ocean circulation en_US
dc.subject Estuaries en_US
dc.subject Turbulence en_US
dc.title The importance of tidal and lateral asymmetries in stratification to residual circulation in partially mixed estuaries en_US
dc.type Article en_US
dc.identifier.doi 10.1175/jpo3071.1

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