Lateral Circulation Generates Flood Tide Stratification and Estuarine Exchange Flow in a Curved Tidal Inlet

Johannes Becherer Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany

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Mark T. Stacey Civil and Environmental Engineering Department, University of California Berkeley, Berkeley, California

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Lars Umlauf Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany

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Hans Burchard Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany

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Abstract

Cross-channel transect measurements of microstructure and velocity in a well-mixed and curved tidal inlet in the German Wadden Sea show the occurrence of significant late flood stratification. This stratification is found to be a result of lateral straining. This study observes a strong single-cell lateral circulation, which is strongly pronounced at late flood and absent during most of ebb. This tidal asymmetry is caused by a systematic interplay between centrifugal forcing and the lateral baroclinic pressure gradient. During flood a positive feedback between the terms generates strong lateral circulation, whereas during ebb a negative feedback leads to a suppression of the cross-channel exchange. A theoretical framework based on vorticity is developed, which allows lateral and longitudinal circulation to be studied in a consistent way. With this framework it is possible to show that the tidal asymmetry of the lateral flow is a major driver of residual longitudinal estuarine circulation, here identified with the tidally averaged across-channel vorticity component.

Denotes Open Access content.

Corresponding author address: Johannes Becherer, Leibniz Institute for Baltic Sea Research Warnemünde, Seestraße 15, Rostock, D-18119, Germany. E-mail: johannes.becherer@io-warnemuende.de

Abstract

Cross-channel transect measurements of microstructure and velocity in a well-mixed and curved tidal inlet in the German Wadden Sea show the occurrence of significant late flood stratification. This stratification is found to be a result of lateral straining. This study observes a strong single-cell lateral circulation, which is strongly pronounced at late flood and absent during most of ebb. This tidal asymmetry is caused by a systematic interplay between centrifugal forcing and the lateral baroclinic pressure gradient. During flood a positive feedback between the terms generates strong lateral circulation, whereas during ebb a negative feedback leads to a suppression of the cross-channel exchange. A theoretical framework based on vorticity is developed, which allows lateral and longitudinal circulation to be studied in a consistent way. With this framework it is possible to show that the tidal asymmetry of the lateral flow is a major driver of residual longitudinal estuarine circulation, here identified with the tidally averaged across-channel vorticity component.

Denotes Open Access content.

Corresponding author address: Johannes Becherer, Leibniz Institute for Baltic Sea Research Warnemünde, Seestraße 15, Rostock, D-18119, Germany. E-mail: johannes.becherer@io-warnemuende.de
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  • Alaee, M. J., G. Ivey, and C. Pattiaratchi, 2004: Secondary circulation induced by flow curvature and Coriolis effects around headlands and islands. Ocean Dyn., 54, 2738, doi:10.1007/s10236-003-0058-3.

    • Search Google Scholar
    • Export Citation
  • Becherer, J., H. Burchard, G. Flöser, V. Mohrholz, and L. Umlauf, 2011: Evidence of tidal straining in well-mixed channel flow from micro-structure observations. Geophys. Res. Lett., 38, L17611, doi:10.1029/2011GL049005.

    • Search Google Scholar
    • Export Citation
  • Blanckaert, K., and H. De Vriend, 2004: Secondary flow in sharp open-channel bends. J. Fluid Mech., 498, 353380, doi:10.1017/S0022112003006979.

    • Search Google Scholar
    • Export Citation
  • Buijsman, M., and H. Ridderinkhof, 2008: Variability of secondary currents in a weakly stratified tidal inlet with low curvature. Cont. Shelf Res., 28, 17111723, doi:10.1016/j.csr.2008.04.001.

    • Search Google Scholar
    • Export Citation
  • Burchard, H., and H. Baumert, 1998: The formation of estuarine turbidity maxima due to density effects in the salt wedge. A hydrodynamic process study. J. Phys. Oceanogr., 28, 309321, doi:10.1175/1520-0485(1998)028<0309:TFOETM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Burchard, H., and R. Hofmeister, 2008: A dynamic equation for the potential energy anomaly for analysing mixing and stratification in estuaries and coastal seas. Estuarine Coastal Shelf Sci., 77, 679687, doi:10.1016/j.ecss.2007.10.025.

    • Search Google Scholar
    • Export Citation
  • Burchard, H., and R. D. Hetland, 2010: Quantifying the contributions of tidal straining and gravitational circulation to residual circulation in periodically stratified tidal estuaries. J. Phys. Oceanogr., 40, 12431262, doi:10.1175/2010JPO4270.1.

    • Search Google Scholar
    • Export Citation
  • Burchard, H., G. Flöser, J. V. Staneva, R. Riethmüller, and T. Badewien, 2008: Impact of density gradients on net sediment transport into the Wadden Sea. J. Phys. Oceanogr., 38, 566587, doi:10.1175/2007JPO3796.1.

    • Search Google Scholar
    • Export Citation
  • Burchard, H., R. Hetland, E. Schulz, and H. Schuttelaars, 2011: Drivers of residual estuarine circulation in tidally energetic estuaries: Straight and irrotational channels with parabolic cross section. J. Phys. Oceanogr., 41, 548570, doi:10.1175/2010JPO4453.1.

    • Search Google Scholar
    • Export Citation
  • Chant, R. J., 2002: Secondary circulation in a region of flow curvature: Relationship with tidal forcing and river discharge. J. Geophys. Res., 107, 3131, doi:10.1029/2001JC001082.

    • Search Google Scholar
    • Export Citation
  • Chant, R. J., and R. E. Wilson, 1997: Secondary circulation in a highly stratified estuary. J. Geophys. Res.,102, 23 207– 23 215, doi:10.1029/97JC00685.

  • Cheng, P., R. E. Wilson, R. J. Chant, D. C. Fugate, and R. D. Flood, 2009: Modeling influence of stratification on lateral circulation in a stratified estuary. J. Phys. Oceanogr., 39, 23242337, doi:10.1175/2009JPO4157.1.

    • Search Google Scholar
    • Export Citation
  • Collignon, A., and M. Stacey, 2012: Intratidal dynamics of fronts and lateral circulation at the shoal–channel interface in a partially stratified estuary. J. Phys. Oceanogr., 42, 869883, doi:10.1175/JPO-D-11-065.1.

    • Search Google Scholar
    • Export Citation
  • De Boer, G. J., J. D. Pietrzak, and J. C. Winterwerp, 2008: Using the potential energy anomaly equation to investigate tidal straining and advection of stratification in a region of freshwater influence. Ocean Modell., 22, 111, doi:10.1016/j.ocemod.2007.12.003.

    • Search Google Scholar
    • Export Citation
  • Dillon, T. M., 1982: Vertical overturns: A comparison of Thorpe and Ozmidov length scales. J. Geophys. Res., 87, 96019613, doi:10.1029/JC087iC12p09601.

    • Search Google Scholar
    • Export Citation
  • Drinker, P., 1961: Boundary shear stresses in curved trapezoidal channels. Ph.D. thesis, Massachusetts Institute of Technology, 130 pp.

  • Dronkers, J., 1996: The influence of buoyancy on transverse circulation and on estuarine dynamics. Buoyancy Effects on Coastal and Estuarine Dynamics, Geophys. Monogr., Vol. 53, Amer. Geophys. Union, 341–356, doi:10.1029/CE053p0341.

  • Fer, I., 2006: Scaling turbulent dissipation in an Arctic fjord. Deep-Sea Res. II, 53, 7795, doi:10.1016/j.dsr2.2006.01.003.

  • Flöser, G., H. Burchard, and R. Riethmüller, 2011: Observational evidence for estuarine circulation in the German Wadden Sea. Cont. Shelf Res., 31, 16331639, doi:10.1016/j.csr.2011.03.014.

    • Search Google Scholar
    • Export Citation
  • Geyer, W. R., 1993: Three-dimensional tidal flow around headlands. J. Geophys. Res., 98, 955966, doi:10.1029/92JC02270.

  • Geyer, W. R., and P. MacCready, 2014: The estuarine circulation. Annu. Rev. Fluid Mech., 46, 175–197, doi:10.1146/annurev-fluid-010313-141302.

    • Search Google Scholar
    • Export Citation
  • Hansen, D. V., and M. Rattray, 1965: Gravitational circulation in straits and estuaries. J. Mar. Res., 23, 104122.

  • Hofmeister, R., H. Burchard, and K. Bolding, 2009: A three-dimensional model study on processes of stratification and de-stratification in the Limfjord. Cont. Shelf Res., 29, 15151524, doi:10.1016/j.csr.2009.04.004.

    • Search Google Scholar
    • Export Citation
  • Huijts, K., H. Schuttelaars, H. De Swart, and C. Friedrichs, 2009: Analytical study of the transverse distribution of along-channel and transverse residual flows in tidal estuaries. Cont. Shelf Res., 29, 89100, doi:10.1016/j.csr.2007.09.007.

    • Search Google Scholar
    • Export Citation
  • Jay, D., and J. Musiak, 1994: Particle trapping in estuarine tidal flows. J. Geophys. Res., 99, 20 44520 461, doi:10.1029/94JC00971.

  • Jay, D., and J. Musiak, 1996: Internal tidal asymmetry in channel flows: Origins and consequences. Mixing in Estuaries and Coastal Seas, Geophys. Monogr., Vol. 50, 211–249, doi:10.1029/CE050p0211.

  • Kalkwijk, J. P. T., and R. Booij, 1986: Adaptation of secondary flow in nearly-horizontal flow. J. Hydraul. Res., 24, 1937, doi:10.1080/00221688609499330.

    • Search Google Scholar
    • Export Citation
  • Kim, Y. H., and G. Voulgaris, 2008: Lateral circulation and suspended sediment transport in a curved estuarine channel: Winyah Bay, SC, USA. J. Geophys. Res., 113, C09006, doi:10.1029/2007JC004509.

    • Search Google Scholar
    • Export Citation
  • Lacy, J. R., and S. G. Monismith, 2001: Secondary currents in a curved, stratified, estuarine channel. J. Geophys. Res., 106, 31 28331 302, doi:10.1029/2000JC000606.

    • Search Google Scholar
    • Export Citation
  • Lacy, J. R., M. Stacey, J. Burau, and S. Monismith, 2003: Interaction of lateral baroclinic forcing and turbulence in an estuary. J. Geophys. Res., 108, 3089, doi:10.1029/2002JC001392.

    • Search Google Scholar
    • Export Citation
  • Lerczak, J., and W. Geyer, 2004: Modeling the lateral circulation in straight, stratified estuaries. J. Phys. Oceanogr., 34, 14101428, doi:10.1175/1520-0485(2004)034<1410:MTLCIS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • MacCready, P., and W. R. Geyer, 2010: Advances in estuarine physics. Annu. Rev. Mar. Sci., 2, 3558, doi:10.1146/annurev-marine-120308-081015.

    • Search Google Scholar
    • Export Citation
  • Nidzieko, N. J., J. L. Hench, and S. G. Monismith, 2009: Lateral circulation in well-mixed and stratified estuarine flows with curvature. J. Phys. Oceanogr., 39, 831851, doi:10.1175/2008JPO4017.1.

    • Search Google Scholar
    • Export Citation
  • Nunes, R., and J. Simpson, 1985: Axial convergence in a well-mixed estuary. Estuarine Coastal Shelf Sci., 20, 637649, doi:10.1016/0272-7714(85)90112-X.

    • Search Google Scholar
    • Export Citation
  • Perkins, H., 1970: The formation of streamwise vorticity in turbulent flow. J. Fluid Mech., 44, 721740, doi:10.1017/S0022112070002112.

    • Search Google Scholar
    • Export Citation
  • Pritchard, D. W., 1952: Salinity distribution and circulation in the Chesapeake Bay estuarine system. J. Mar. Res., 11, 106123.

  • Pritchard, D. W., 1954: A study of the salt balance in a coastal plain estuary. J. Mar. Res., 13, 133144.

  • Pritchard, D. W., 1956: The dynamic structure of a coastal plain estuary. J. Mar. Res., 15, 3342.

  • Purkiani, K., J. Becherer, H. G. Flöser, U. Gräwe, V. Mohrholz, H. M. Schuttelaars, and H. Burchard, 2015: Numerical analysis of stratification and destratification processes in a tidally energetic inlet with an ebb tidal delta. J. Geophys. Res., 120, 225243, doi:10.1002/2014JC010325.

    • Search Google Scholar
    • Export Citation
  • Scully, M. E., and W. Geyer, 2012: The role of advection, straining and mixing on the tidal variability of estuarine stratification. J. Phys. Oceanogr., 42, 855868, doi:10.1175/JPO-D-10-05010.1.

    • Search Google Scholar
    • Export Citation
  • Scully, M. E., W. R. Geyer, and J. A. Lerczak, 2009: The influence of lateral advection on the residual estuarine circulation: A numerical modeling study of the Hudson River estuary. J. Phys. Oceanogr., 39, 107124, doi:10.1175/2008JPO3952.1.

    • Search Google Scholar
    • Export Citation
  • Scully, M. E., W. R. Geyer, and J. H. Trowbridge, 2011: The influence of stratification and nonlocal turbulent production on estuarine turbulence: An assessment of turbulence closure with field observations. J. Phys. Oceanogr., 41, 166185, doi:10.1175/2010JPO4470.1.

    • Search Google Scholar
    • Export Citation
  • Seim, H. E., and M. C. Gregg, 1997: The importance of aspiration and channel curvature in producing strong vertical mixing over a sill. J. Geophys. Res., 102, 34513472, doi:10.1029/96JC03415.

    • Search Google Scholar
    • Export Citation
  • Simpson, J. H., 1981: The shelf-sea fronts: Implications of their existence and behaviour. Roy. Soc. London Philos. Trans., A302, 531543, doi:10.1098/rsta.1981.0181.

    • Search Google Scholar
    • Export Citation
  • Simpson, J. H., J. Brown, J. Matthews, and G. Allen, 1990: Tidal straining, density currents, and stirring in the control of estuarine stratification. Estuaries Coasts, 13, 125132, doi:10.2307/1351581.

    • Search Google Scholar
    • Export Citation
  • Stacey, M. T., 1996: Turbulent mixing and residual circulation in a partially stratified estuary. Ph.D. thesis, Stanford University, 209 pp.

  • Stacey, M. T., J. R. Burau, and S. G. Monismith, 2001: Creation of residual flows in a partially stratified estuary. J. Geophys. Res., 106, 17 01317 037, doi:10.1029/2000JC000576.

    • Search Google Scholar
    • Export Citation
  • Stacey, M. T., J. P. Fram, and F. K. Chow, 2008: Role of tidally periodic density stratification in the creation of estuarine subtidal circulation. J. Geophys. Res.,113, C08016, doi:10.1029/2007JC004581.

  • Stanev, E., G. Flöser, and J. Wolff, 2003: First- and higher-order dynamical controls on water exchanges between tidal basins and the open ocean. A case study for the East Frisian Wadden Sea. Ocean Dyn., 53, 146165, doi:10.1007/s10236-003-0029-8.

    • Search Google Scholar
    • Export Citation
  • Umlauf, L., and H. Burchard, 2003: A generic length-scale equation for geophysical turbulence models. J. Mar. Res., 61, 235265, doi:10.1357/002224003322005087.

    • Search Google Scholar
    • Export Citation
  • Umlauf, L., and H. Burchard, 2005: Second-order turbulence closure models for geophysical boundary layers. A review of recent work. Cont. Shelf Res., 25, 795827, doi:10.1016/j.csr.2004.08.004.

    • Search Google Scholar
    • Export Citation
  • van der Lee, E. M., and L. Umlauf, 2011: Internal-wave mixing in the Baltic Sea: Near-inertial waves in the absence of tides. J. Geophys. Res.,116, C10016, doi:10.1029/2011JC007072.

  • Verspecht, F. I., H. Burchard, T. P. Rippeth, M. J. Howarth, and J. H. Simpson, 2009: Processes impacting on stratification in a region of freshwater influence: Application to Liverpool Bay. J. Geophys. Res., 114, C11022, doi:10.1029/2009JC005475.

    • Search Google Scholar
    • Export Citation
  • Waterhouse, A. F., and A. Valle-Levinson, 2010: Transverse structure of subtidal flow in a weakly stratified subtropical tidal inlet. Cont. Shelf Res., 30, 281292, doi:10.1016/j.csr.2009.11.008.

    • Search Google Scholar
    • Export Citation
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