Tidal Intrusion Fronts, Surface Convergence, and Mixing in an Estuary with Complex Topography
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phoc-JPO-D-23-0131.1.pdf
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18.86 MB
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Author(s)
Bo, Tong
Ralston, David
Mikhail, Adrian
Garcia, P
Geyer, And
Date Issued
February 9, 2024
Journal
Journal of Physical Oceanography
Publisher
American Meteorological Society
Citation
Bo, T., D. K. Ralston, A. M. P. Garcia, and W. R. Geyer, 2024: Tidal Intrusion Fronts, Surface Convergence, and Mixing in an Estuary with Complex Topography. J. Phys. Oceanogr., 54, 653–677.
Version
Final published version
Abstract
Observations from a tidal estuary show that tidal intrusion fronts occur regularly during flood tides near topographic features including constrictions and bends. A realistic model is used to study the generation of these fronts and their influence on stratification and mixing in the estuary. At the constriction, flow separation occurs on both sides of the jet flow downstream of the narrow opening, leading to sharp lateral salinity gradients and baroclinic secondary circulation. A tidal intrusion front, with a V-shaped convergence zone on the surface, is generated by the interaction between secondary circulation and the jet flow. Stratification is created at the front due to the straining of lateral salinity gradients by secondary circulation. Though stratification is expected to suppress turbulence, strong turbulent mixing is found near the surface front. The intense mixing is attributed to enhanced vertical shear due to both frontal baroclinicity and the twisting of lateral shear by secondary circulation. In the bend, flow separation occurs along the inner bank, resulting in lateral salinity gradients, secondary circulation, frontogenesis, and enhanced mixing near the front. In contrast to the V-shaped front at the constriction, an oblique linear surface convergence front occurs in the bend, which resembles a one-sided tidal intrusion front. Moreover, in addition to baroclinicity, channel curvature also affects secondary circulation, frontogenesis, and mixing in the bend. Overall in the estuary, the near-surface mixing associated with tidal intrusion fronts during flood tides is similar in magnitude to bottom boundary layer mixing that occurs primarily during ebbs.
Subjects
Estuaries
Fronts
Mixing
Secondary circulation
Tides
Numerical analysis/modeling
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1175/JPO-D-23-0131.1
