The importance of tidal and lateral asymmetries in stratification to residual circulation in partially mixed estuaries
MetadataShow full item record
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.
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.
Suggested CitationArticle: Scully, Malcolm E., Friedrichs, Carl T., "The importance of tidal and lateral asymmetries in stratification to residual circulation in partially mixed estuaries", Journal of Physical Oceanography 37 (2007): 1496-1511, DOI:10.1175/jpo3071.1, https://hdl.handle.net/1912/4149
Showing items related by title, author, creator and subject.
The influence of lateral advection on the residual estuarine circulation : a numerical modeling study of the Hudson River Estuary Scully, Malcolm E.; Geyer, W. Rockwell; Lerczak, James A. (American Meteorological Society, 2009-01)In most estuarine systems it is assumed that the dominant along-channel momentum balance is between the integrated pressure gradient and bed stress. Scaling the amplitude of the estuarine circulation based on this balance ...
Lateral circulation and sediment transport driven by axial winds in an idealized, partially mixed estuary Chen, Shih-Nan; Sanford, Lawrence P.; Ralston, David K. (American Geophysical Union, 2009-12-03)A 3D hydrodynamic model (ROMS) is used to investigate lateral circulation in a partially mixed estuary driven by axial wind events and to explore the associated transport of sediments. The channel is straight with a ...
Wang, Tao; Geyer, W. Rockwell; Engel, Patricia A.; Jiang, Wensheng; Feng, Shizuo (American Meteorological Society, 2015-11)Tidal oscillatory salt transport, induced by the correlation between tidal variations in salinity and velocity, is an important term for the subtidal salt balance under the commonly used Eulerian method of salt transport ...