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  • 1
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 118 (2013): 2774–2792, doi:10.1002/jgrc.20217.
    Beschreibung: The spatial distribution of turbulent dissipation rates and internal wavefield characteristics is analyzed across two contrasting regimes of the Antarctic Circumpolar Current (ACC), using microstructure and finestructure data collected as part of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). Mid-depth turbulent dissipation rates are found to increase from inline image in the Southeast Pacific to inline image in the Scotia Sea, typically reaching inline image within a kilometer of the seabed. Enhanced levels of turbulent mixing are associated with strong near-bottom flows, rough topography, and regions where the internal wavefield is found to have enhanced energy, a less-inertial frequency content and a dominance of upward propagating energy. These results strongly suggest that bottom-generated internal waves play a major role in determining the spatial distribution of turbulent dissipation in the ACC. The energy flux associated with the bottom internal wave generation process is calculated using wave radiation theory, and found to vary between 0.8 mW m−2 in the Southeast Pacific and 14 mW m−2 in the Scotia Sea. Typically, 10%–30% of this energy is found to dissipate within 1 km of the seabed. Comparison between turbulent dissipation rates inferred from finestructure parameterizations and microstructure-derived estimates suggests a significant departure from wave-wave interaction physics in the near-field of wave generation sites.
    Beschreibung: The DIMES experiment is supported by the Natural Environment Research Council (NERC) of the U.K. and U.S. National Science Foundation. K.L.S. and J.A.B. are supported by NERC.
    Beschreibung: 2013-12-04
    Schlagwort(e): Turbulent dissipation ; Internal wave ; Antarctic Circumpolar Current ; Mixing
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
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    American Geophysical Union
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): C09019, doi:10.1029/2010JC006818.
    Beschreibung: There is an ongoing debate concerning the distribution of eddy stirring across the Antarctic Circumpolar Current (ACC) and the nature of its controlling processes. The problem is addressed here by estimating the isentropic eddy diffusivity κ from a collection of hydrographic and altimetric observations, analyzed in a mixing length theoretical framework. It is shown that, typically, κ is suppressed by an order of magnitude in the upper kilometer of the ACC frontal jets relative to their surroundings, primarily as a result of a local reduction of the mixing length. This observation is reproduced by a quasi-geostrophic theory of eddy stirring across a broad barotropic jet based on the scaling law derived by Ferrari and Nikurashin (2010). The theory interprets the observed widespread suppression of the mixing length and κ in the upper layers of frontal jets as the kinematic consequence of eddy propagation relative to the mean flow within jet cores. Deviations from the prevalent regime of mixing suppression in the core of upper-ocean jets are encountered in a few special sites. Such ‘leaky jet’ segments appear to be associated with sharp stationary meanders of the mean flow that are generated by the interaction of the ACC with major topographic features. It is contended that the characteristic thermohaline structure of the Southern Ocean, consisting of multiple upper-ocean thermohaline fronts separated and underlaid by regions of homogenized properties, is largely a result of the widespread suppression of eddy stirring by parallel jets.
    Beschreibung: This study was conducted during A.C.N. G.’s stay at MIT, which was supported jointly by MIT and the U.K. Natural Environment Research Council (NERC) through a NERC Advanced Research Fellowship (NE/C517633/1). R.F. acknowledges the support of NSFaward OCE‐0825376. K.P.’s participation in this work was supported by WHOI bridge support funds.
    Schlagwort(e): Antarctic Circumpolar Current ; Eddy stirring ; Mixing
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2022-11-10
    Beschreibung: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in [citation], doi:[doi]. Gommenginger, C., Chapron, B., Hogg, A., Buckingham, C., Fox-Kemper, B., Eriksson, L., Soulat, F., Ubelmann, C., Ocampo-Torres, F., Nardelli, B. B., Griffin, D., Lopez-Dekker, P., Knudsen, P., Andersen, O., Stenseng, L., Stapleton, N., Perrie, W., Violante-Carvalho, N., Schulz-Stellenfleth, J., Woolf, D., Isern-Fontanet, J., Ardhuin, F., Klein, P., Mouche, A., Pascual, A., Capet, X., Hauser, D., Stoffelen, A., Morrow, R., Aouf, L., Breivik, O., Fu, L., Johannessen, J. A., Aksenov, Y., Bricheno, L., Hirschi, J., Martin, A. C. H., Martin, A. P., Nurser, G., Polton, J., Wolf, J., Johnsens, H., Soloviev, A., Jacobs, G. A., Collard, F., Groom, S., Kudryavtsev, V., Wilkin, J., Navarro, V., Babanin, A., Martin, M., Siddorn, J., Saulter, A., Rippeth, T., Emery, B., Maximenko, N., Romeiser, R., Graber, H., Azcarate, A. A., Hughes, C. W., Vandemark, D., da Silva, J., Van Leeuwen, P. J., Naveira-Garabato, A., Gemmrich, J., Mahadevan, A., Marquez, J., Munro, Y., Doody, S., & Burbidge, G. SEASTAR: A mission to study ocean submesoscale dynamics and small-scale atmosphere-ocean processes in coastal, shelf and polar seas. Frontiers in Marine Science, 6, (2019):457, doi:10.3389/fmars.2019.00457.
    Beschreibung: High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer re-stratification. Small-scale processes particularly dominate in coastal, shelf and polar seas where they mediate important exchanges between land, ocean, atmosphere and the cryosphere, e.g., freshwater, pollutants. As numerical models continue to evolve toward finer spatial resolution and increasingly complex coupled atmosphere-wave-ice-ocean systems, modern observing capability lags behind, unable to deliver the high-resolution synoptic measurements of total currents, wind vectors and waves needed to advance understanding, develop better parameterizations and improve model validations, forecasts and projections. SEASTAR is a satellite mission concept that proposes to directly address this critical observational gap with synoptic two-dimensional imaging of total ocean surface current vectors and wind vectors at 1 km resolution and coincident directional wave spectra. Based on major recent advances in squinted along-track Synthetic Aperture Radar interferometry, SEASTAR is an innovative, mature concept with unique demonstrated capabilities, seeking to proceed toward spaceborne implementation within Europe and beyond.
    Beschreibung: CG and AM received funding from the United Kingdom Centre for Earth Observation Instrumentation SEASTAR+ project (Contract No. RP10G0435A02). PVL was supported by the European Research Council (ERC) CUNDA project 694509 under the European Union Horizon 2020 Research and Innovation Program.
    Schlagwort(e): Satellite ; Air sea interactions ; Upper ocean dynamics ; Submesoscale ; Coastal ; Marginal ice zone ; Radar ; Along-track interferometry
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Einschränkungen Verfügbarkeit
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