The turbulent diffusivity estimation in Prydz Bay, Antarctic

doi:10.3969/j.issn.1001-909X.2017.01.002

Abstract

Abstract: Thorpe scale and turbulent diffusivities in Prydz Bay of Antarctica were calculated based on Thorpe method and Conductivity-Temperature-Depth data. The strength of turbulent overturn was analyzed and its spatial distribution was also investigated. The results show that the larger Thorpe scale and turbulent diffusivities occur in rough topographic area and near the sea floor, and the maximum value of turbulent diffusivities exceeds 10^-2 m²/s, which is about two or three orders of magnitude larger than that in the open ocean. Turbulent diffusivities and dissipation rate of turbulent kinetic energy show high-low-high vertical structure in some observational stations, especially in deep area. The larger values of buoyancy frequency appear in upper 500 m water column in deep area, but this phenomenon is not obvious in shallow area. The dissipation rates of turbulent kinetic energy in the stations around the point(67.25°S,73°E) and along the 78°E sections are quite large, which exceed 10^-6 w/kg, and even reach 10^-5 w/kg in a few stations.

Key words: Prydz Bay, Thorpe scale, turbulent diffusivities, dissipation rate of turbulent kinetic energy

CLC Number:

P731

DING Wen-xiang, LIANG Chu-jin, LIAO Guang-hong, GAO Li-Bao. The turbulent diffusivity estimation in Prydz Bay, Antarctic[J]. Journal of Marine Sciences, 2017, 35(1): 14-24.

References

[1] MUNK W H. Abyssal recipes[J].Deep Sea Research and Oceanographic Abstracts,1966,13(4):707-730.
[2] GREGG M C. Diapycnal mixing in the thermocline: A review[J]. Journal of Geophysical Research: Oceans (1978—2012),1987,92(C5):5 249-5 286.
[3] LEDWELL J R, WATSON A J, LAW C S. Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment[J]. Nature,1993,364(6439):701-703.
[4] LUECK R G, MUDGE T D. Topographically induced mixing around a shallow seamount[J]. Science,1997,276(5320):1 831-1 833.
[5] POLZIN K L, TOOLE J M, LEDWELL J R, et al. Spatial variability of turbulent mixing in the abyssal ocean[J]. Science,1997,276(5309):93-96.
[6] CARTER G S, GREGG M C. Intense, variable mixing near the head of Monterey Submarine Canyon[J]. Journal of Physical Oceanography,2002,32(11):3 145-3 165.
[7] HEYWOOD K J, GARABATO A C N, STEVENS D P. High mixing rates in the abyssal Southern Ocean[J]. Nature,2002,415(6875):1 011-1 014.
[8] GARABATO A C N, POLZIN K L, KING B A, et al. Widespread intense turbulent mixing in the Southern Ocean[J]. Science,2004,303(5655):210-213.
[9] GARABATO A C N, STEVENS D P, WATSON A J, et al. Short-circuiting of the overturning circulation in the Antarctic Circumpolar Current[J]. Nature,2007,447(7141):194-197.
[10] SLOYAN B M. Spatial variability of mixing in the Southern Ocean[J]. Geophysical Research Letters,2005,32(18):doi:10.1029/2005GL023568.
[11] LEDWELL J R, St. LAURENT L C, GIRTON J B, et al. Diapycnal mixing in the Antarctic circumpolar current[J]. Journal of Physical Oceanography,2011,41(1):241-246.
[12] NAVEIRA GARABATO A C, OLIVER K I C, WATSON A J, et al. Turbulent diapycnal mixing in the Nordic seas[J]. Journal of Geophysical Research: Oceans,2004,109(C12010):doi:10.1029/2004JC002411.
[13] KUNZE E, FIRING E, HUMMON J M, et al. Global abyssal mixing inferred from lowered ADCP shear and CTD strain profiles[J]. Journal of Physical Oceanography,2006,36(8):1 553-1 576.
[14] THORPE S A. Turbulence and mixing in a Scottish loch[J]. Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences,1977,286(1334):125-181.
[15] DILLON T M. Vertical overturns: A comparison of Thorpe and Ozmidov length scales[J]. J Geophys Res,1982,87(C12):9 601-9 613.
[16] PARK Y H, FUDA J L, DURAND I, et al. Internal tides and vertical mixing over the Kerguelen Plateau[J]. Deep Sea Research Part II: Topical Studies in Oceanography,2008,55(5):582-593.
[17] FERRON B, MERCIER H, SPEER K, et al. Mixing in the Romanche fracture zone[J]. Journal of Physical Oceanography,1998,28(10):1 929-1 945.
[18] GARGETT A, GARNER T. Determining Thorpe scales from ship-lowered CTD density profiles[J]. Journal of Atmospheric and Oceanic Technology,2008,25(9):1 657-1 670.
[19] OZMIDOV R V. On the turbulent exchange in a stably stratified ocean[J]. Izv Acad Sci USSR, Atmos Oceanic Phys,1965,1(8):853-860.
[20] CRAWFORD W R. A comparison of length scales and decay times of turbulence in stably stratified flows[J]. Journal of Physical Oceanography,1986,16(11):1 847-1 854.
[21] MUENCH R, PADMAN L, GORDON A, et al. A dense water outflow from the Ross Sea, Antarctica: Mixing and the contribution of tides[J]. Journal of Marine Systems,2009,77(4):369-387.
[22] YANG Qing-xuan, TIAN Ji-wei, ZHAO Wei, et al. Turbulent dissipation and mixing in Prydz Bay[J]. Chinese Journal of Oceanology and Limnology,2013,31(2):445-453.
[23] HUANG Yi-pu, CAI Ping-he, CHEN Min, et al.Deuterium tracing study on water mass and circulation in Prydz Bay and its adjacent sea[M]//CHEN Li-qi.Study on the response and feedback of antarctic region to global change.Beijing:China Ocean Press,2004:59-71.
黄奕普,菜平河,陈敏,等.普里兹湾及临近海域水团、环流的氘示踪研究[M]//陈立奇.南极地区对全球变化的响应与反馈作用研究.北京:海洋出版社,2004:59-71.
[24] VAZ R A N, LENNON G W. Physical oceanography of the Prydz Bay region of Antarctic waters[J]. Deep Sea Research Part I: Oceanographic Research Papers,1996,43(5):603-641.