Articles | Volume 19, issue 6
https://doi.org/10.5194/os-19-1633-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-19-1633-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
29 Nov 2023
Research article |
| 29 Nov 2023
| 29 Nov 2023
Observations and modeling of tidally generated high-frequency velocity fluctuations downstream of a channel constriction
Håvard Espenes
CORRESPONDING AUTHOR
Department of Geosciences, University of Oslo, Oslo, Norway
Akvaplan-niva, Fram Centre, Tromsø, Norway
Pål Erik Isachsen
Department of Geosciences, University of Oslo, Oslo, Norway
Norwegian Meteorological Institute, Oslo, Norway
Ole Anders Nøst
Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
Oceanbox.io, Trondheim, Norway
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Cited articles
Afanasyev, Y.: Formation of vortex dipoles, Physics of fluids, 18, 037103, https://doi.org/10.1063/1.2182006, 2006. a, b, c
Albagnac, J., Moulin, F. Y., Eiff, O., Lacaze, L., and Brancher, P.: A three-dimensional experimental investigation of the structure of the spanwise vortex generated by a shallow vortex dipole, Environ. Fluid Mech., 14, 957–970, 2014. a
Blakely, C. P., Ling, G., Pringle, W. J., Contreras, M. T., Wirasaet, D., Westerink, J. J., Moghimi, S., Seroka, G., Shi, L., Myers, E., et al.: Dissipation and bathymetric sensitivities in an unstructured mesh global tidal model, J. Geophys. Res.-Oceans, 127, e2021JC018178, https://doi.org/10.1029/2021JC018178, 2022. a
Børve, E., Isachsen, P. E., and Nøst, O. A.: Rectified tidal transport in Lofoten–Vesterålen, northern Norway, Ocean Sci., 17, 1753–1773, https://doi.org/10.5194/os-17-1753-2021, 2021. a, b
Chen, C., Beardsley, R. C., Cowles, G., Qi, J., Lai, Z., Gao, G., et al.: An unstructured grid, finite-volume coastal ocean model: FVCOM user manual, SMAST/UMASSD, 6–8, 2006. a
Codiga, D. L.: Unified tidal analysis and prediction using the UTide Matlab functions, https://doi.org/10.13140/RG.2.1.3761.2008, 2011. a, b
Egbert, G. D. and Erofeeva, S. Y.: Efficient inverse modeling of barotropic ocean tides, J. Atmos. Ocean. Tech., 19, 183–204, 2002. a
Farmer, D. M. and Freeland, H. J.: The physical oceanography of fjords, Prog. Oceanogr., 12, 147–219, 1983. a
Feng, D., Hodges, B. R., Socolofsky, S. A., and Thyng, K. M.: Tidal eddies at a narrow channel inlet in operational oil spill models, Mar. Pollut. Bull., 140, 374–387, 2019. a
Fujiwara, T., Nakata, H., and Nakatsuji, K.: Tidal-jet and vortex-pair driving of the residual circulation in a tidal estuary, Cont. Shelf Res., 14, 1025–1038, 1994. a
Gjevik, B., Nøst, E., and Straume, T.: Model simulations of the tides in the Barents Sea, J. Geophys. Res.-Oceans, 99, 3337–3350, 1994. a
Google: http://maps.google.co.uk, 2021. a
Inall, M., Cottier, F., Griffiths, C., and Rippeth, T.: Sill dynamics and energy transformation in a jet fjord, Ocean Dynam., 54, 307–314, 2004. a
Kartverket: Bathymetric data, https://kartkatalog.geonorge.no/metadata/dybdedata-terrengmodeller-50-meters-grid/67a3a191-49cc-45bc-baf0-eaaf7c513549 (last access: 26 January 2022), 2022. a
Kerr, P., Martyr, R., Donahue, A., Hope, M., Westerink, J., Luettich Jr, R., Kennedy, A., Dietrich, J., Dawson, C., and Westerink, H.: US IOOS coastal and ocean modeling testbed: Evaluation of tide, wave, and hurricane surge response sensitivities to mesh resolution and friction in the Gulf of Mexico, J. Geophys. Res.-Oceans, 118, 4633–4661, 2013. a
Kobayashi, M. H., Pereira, J. M., and Pereira, J. C.: A conservative finite-volume second-order-accurate projection method on hybrid unstructured grids, J. Comput. Phys., 150, 40–75, 1999. a
Lee, J., Lee, J., Yun, S.-L., and Kim, S.-K.: Three-Dimensional Unstructured Grid Finite-Volume Model for Coastal and Estuarine Circulation and Its Application, Water, 12, 2752, https://doi.org/10.3390/w12102752, 2020. a
Lyu, H. and Zhu, J.: Impact of the bottom drag coefficient on saltwater intrusion in the extremely shallow estuary, J. Hydrol., 557, 838–850, 2018. a
Mayo, T., Butler, T., Dawson, C., and Hoteit, I.: Data assimilation within the Advanced Circulation (ADCIRC) modeling framework for the estimation of Manning’s friction coefficient, Ocean Model., 76, 43–58, 2014. a
Nicolau del Roure, F., Socolofsky, S. A., and Chang, K.-A.: Structure and evolution of tidal starting jet vortices at idealized barotropic inlets, J. Geophys. Res.-Oceans, 114, C5, https://doi.org/10.1029/2008JC004997, 2009. a, b
Old, C. and Vennell, R.: Acoustic Doppler current profiler measurements of the velocity field of an ebb tidal jet, J. Geophys. Res.-Oceans, 106, 7037–7049, 2001. a
Persson, P.-O. and Strang, G.: A simple mesh generator in MATLAB, SIAM review, 46, 329–345, 2004. a
Sælen, O. H.: The Hydrography of Some Fjords in Northern Norway: Balsfjord, Ulfsfjord, Grøtsund, Vengsøfjord and Malangen, Tromsø museum, URL https://www.nb.no/items/URN:NBN:no-nb_digibok_2008042204082 (last access: 28 November 2023), 1950. a
Smagorinsky, J.: General circulation experiments with the primitive equations: I. The basic experiment, Mon. Weather Rev., 91, 99–164, 1963. a
Stigebrandt, A.: Some aspects of tidal interaction with fjord constrictions, Estuar. Coast. Mar. Sci., 11, 151–166, 1980. a
Stommel, H. and Farmer, H. G.: On the nature of estuarine circulation, Part I (chapters 3 and 4), Tech. Rep., Woods hole oceanographic institution, https://doi.org/10.1575/1912/2032, 1952. a
uk-fvcom branch: https://github.com/UK-FVCOM-Usergroup/uk-fvcom, last access: 9 February 2023. a
van Heijst, G.: Shallow flows: 2D or not 2D?, Environ. Fluid Mech., 14, 945–956, 2014. a
Wells, M. G. and van Heijst, G.-J. F.: A model of tidal flushing of an estuary by dipole formation, Dynam. Atmos. Oceans, 37, 223–244, 2003. a
Whilden, K. A., Socolofsky, S. A., Chang, K.-A., and Irish, J. L.: Using surface drifter observations to measure tidal vortices and relative diffusion at Aransas Pass, Texas, Environ. Fluid Mech., 14, 1147–1172, 2014. a
Short summary
We show that tidally generated eddies generated near the constriction of a channel can drive a strong and fluctuating flow field far downstream of the channel constriction itself. The velocity signal has been observed in other studies, but this is the first study linking it to a physical process. Eddies such as those we found are generated because of complex coastal geometry, suggesting that, for example, land-reclamation projects in channels may enhance current shear over a large area.
We show that tidally generated eddies generated near the constriction of a channel can drive a...
