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  • Padman, Laurie  (3)
  • 1
    Online-Ressource
    Online-Ressource
    American Geophysical Union (AGU) ; 1992
    In:  Journal of Geophysical Research: Oceans Vol. 97, No. C8 ( 1992-08-15), p. 12639-12652
    In: Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), Vol. 97, No. C8 ( 1992-08-15), p. 12639-12652
    Kurzfassung: Recent current measurements obtained from drifting platforms over the Yermak Plateau in the eastern Arctic Ocean confirm that the plateau is a region of greatly enhanced diurnal tidal currents. Modulation of the diurnal currents is clearly related to the plateau topography, as has been previously proposed. We show, however, that temporal variability due to spring‐neap modulation must also be considered in interpreting records from drifting platforms. We review simple models of tidal current amplification in this region and find that the previous assumption of near‐resonant, barotropic shelf waves propagating around the plateau's entire perimeter is inconsistent with the true topography. Instead, we propose that the diurnal variability is due to topographic shelf waves at the K 1 and O 1 tidal frequencies that are generated at points on the plateau's perimeter where the waves' group velocities are near zero. Observed cross‐slope variations in ellipticity, orientation, and magnitude of tidal oscillations are consistent with the presence of topographic waves generated in this manner. The topographic enhancement of the diurnal tide near the Yermak Plateau has important consequences for the sea ice cover, hydrography, and general circulation of this region. For example, the stress divergence applied by the tidal currents at the ice base greatly exceeds the typical divergence of the surface wind stress, and tides may therefore be important to local ice deformation. The strong cross‐slope tidal currents also appear to be responsible for the production of high‐frequency internal wave packets, which are associated with energetic diapycnal mixing in the pycnocline. We also consider the possibility that tidal rectification is responsible for a mean current transporting Atlantic Water clockwise around the plateau.
    Materialart: Online-Ressource
    ISSN: 0148-0227
    Sprache: Englisch
    Verlag: American Geophysical Union (AGU)
    Publikationsdatum: 1992
    ZDB Id: 2033040-6
    ZDB Id: 3094104-0
    ZDB Id: 2130824-X
    ZDB Id: 2016813-5
    ZDB Id: 2016810-X
    ZDB Id: 2403298-0
    ZDB Id: 2016800-7
    ZDB Id: 161666-3
    ZDB Id: 161667-5
    ZDB Id: 2969341-X
    ZDB Id: 161665-1
    ZDB Id: 3094268-8
    ZDB Id: 710256-2
    ZDB Id: 2016804-4
    ZDB Id: 3094181-7
    ZDB Id: 3094219-6
    ZDB Id: 3094167-2
    ZDB Id: 2220777-6
    ZDB Id: 3094197-0
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Acoustical Society of America (ASA) ; 1993
    In:  The Journal of the Acoustical Society of America Vol. 94, No. 3_Supplement ( 1993-09-01), p. 1769-1769
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 94, No. 3_Supplement ( 1993-09-01), p. 1769-1769
    Kurzfassung: Observations from an Arctic ice camp on the Northwest flank of the Yermak Plateau indicate that under some conditions ocean microstructure may be detectable with ‘‘standard’’ acoustic instrumentation (i.e., acoustic Doppler current profilers) of moderately high frequency (150–300 kHz). The data set, collected during the Cooperative Eastern Arctic Experiment (CEAREX), includes simultaneous observations of kinetic energy dissipation rate, temperature dissipation rate, and acoustic backscatter from both 160- and 300-kHz Doppler profilers. The turbulence levels observed during CEAREX were particularly strong (ε≳10−7 W kg−1) and occurred in well-defined patches. Patches in the mixed layer were not associated with backscattered intensity anomalies. However, intensity anomalies of 2 to 6 dB were found to be coincident in time and space with the patches of strong turbulence in the thermocline. The acoustic intensity anomalies were intermittent, presumably because they were detectable only above a threshold that represented the background particulate scattering level. Theoretical predictions of the acoustic intensity level based on the microstructure measurements are used to support the hypothesis that the enhanced scattering levels are due to temperature microstructure rather than variations in particulate scattering.
    Materialart: Online-Ressource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Sprache: Englisch
    Verlag: Acoustical Society of America (ASA)
    Publikationsdatum: 1993
    ZDB Id: 1461063-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Online-Ressource
    Online-Ressource
    Acoustical Society of America (ASA) ; 1992
    In:  The Journal of the Acoustical Society of America Vol. 91, No. 4_Supplement ( 1992-04-01), p. 2428-2428
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 91, No. 4_Supplement ( 1992-04-01), p. 2428-2428
    Kurzfassung: Intriguing new observations from an ice camp, manned during the Cooperative Eastern Arctic Experiment (CEAREX) on the Northwest flank of the Yermak Plateau, indicate that ocean microstructure may be detectable with ‘‘standard’’ acoustic instrumentation (i.e., acoustic Doppler current profilers) of moderately high frequency (150–300 kHz). The strength of the CEAREX data set is the simultaneous observation of kinetic energy dissipation rate, temperature dissipation rate, and acoustic backscatter from both 160- to 300-kHz Doppler profilers. The turbulence levels observed during CEAREX were particularly strong (ε≳10−7 W kg−1) and occurred in well-defined patches. Backscattered intensity anomalies of 2 to 6 dB were found to be coincident in time and space with patches of strong turbulence in the thermocline. It is shown that the acoustic intensity anomalies co-vary with the strength of the turbulent dissipation above a threshold that presumably represents the background particulate scattering level. Theoretical predictions of the acoustic intensity level based on the microstructure measurements are used to support the hypothesis that the enhanced scattering levels are due to temperature anomalies.
    Materialart: Online-Ressource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Sprache: Englisch
    Verlag: Acoustical Society of America (ASA)
    Publikationsdatum: 1992
    ZDB Id: 1461063-2
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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