Research on the new secondary circulation induced by the Ekman flow on the upper ocean

Li Yan; Qiao Fangli; Dai Dejun; Ma Hongyu

doi:10.3969/j.issn.0253-4193.2014.01.002

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Li Yan, Qiao Fangli, Dai Dejun, Ma Hongyu. Research on the new secondary circulation induced by the Ekman flow on the upper ocean[J]. Haiyang Xuebao, 2014, 36(1): 7-19. doi: 10.3969/j.issn.0253-4193.2014.01.002

Citation:

Li Yan, Qiao Fangli, Dai Dejun, Ma Hongyu. Research on the new secondary circulation induced by the Ekman flow on the upper ocean[J]. Haiyang Xuebao, 2014, 36(1): 7-19. doi: 10.3969/j.issn.0253-4193.2014.01.002

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Research on the new secondary circulation induced by the Ekman flow on the upper ocean

doi: 10.3969/j.issn.0253-4193.2014.01.002

1.
College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266003, China;Key Laboratory of Marine Science and Numerical Modeling (MASNUM), The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China
2.
Key Laboratory of Marine Science and Numerical Modeling (MASNUM), The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China

Received Date: 2012-12-24

Abstract

Abstract

The secondary circulation in the mixed layer of the upper ocean can bring the heat, momentum and material from the upper ocean to the subsurface which affects the vertical transport, exchange and mixing in this layer. The studies on the secondary circulation, including its formation mechanism and the interaction with other dynamic process, can enrich our understanding of the ocean upper layer. In this study, we use the linear stability theory to analyze stability of classical Ekman flow on the upper ocean, and present the idea that the instability of the Ekman flow can induced a new kind of secondary circulation. The space scales of this secondary circulation are closely related with the Reynolds number, decaying rate of Ekman flow and the ratio between the horizontal and the vertical turbulent viscosity coefficients etc, and have a wide range from tens of meters to several kilometers. For the secondary circulation of tens of meters, its vertical structure and the deflection angle between the axis of secondary circulation and the main flow are very similar to that of the Langmuir circulation, so this is a new explanation of the formation mechanism for Langmuir circulation. For the secondary circulation of kilometers, it may be responsible for the band structure of surface drifting macroalgae in the western Yellow Sea. In addition, the deflection angle between the axis of the secondary circulation and the main flow is affected by the coriolis force, in the northern hemisphere the secondary circulation turns to the left of the main slow, and to the right in the southern hemisphere.
- upper mixed layer,
- Ekman flow,
- secondary circulation

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References

湛含辉, 成浩, 刘建文, 等. 二次流原理[M]. 长沙:中南大学出版社, 2005: 1-33.

Qiao F L, Dai D J, Simpson J, et al. Banded structure of drifting macroalgae[J]. Marine Pollution Bulletin, 2009, 58(12): 1792-1795.

Lilly D K. On the computational stability of numerical solutions of time-dependent non-linear geophysical fluid dynamics problems[J]. Monthly Weather Review, 1965, 93(1): 11-25.

Lilly D K. On the instability of Ekman boundary flow[J]. Journal of Atmospheric Sciences, 1966, 23: 481-494.

Brown R A. A secondary flow model for the planetary boundary layer[J]. Journal of the Atmosphere Sciences, 1970, 27: 742-757.

Qiao F L. Instability analysis of three-dimensional ocean shear waves[J]. Acta Oceanologica Sinica, 1996, 15(1):1-8.

袁业立, 万振文, 张庆华. 东海黑潮多核结构的运动不稳定性形成机理[J].中国科学D辑: 地球科学, 2002, 12: 1011-1019.

董昌明. 潮流沙脊成因的流体动力学研究及其卫星遥感分析[D]. 青岛:中国科学院海洋研究所, 1997: 27-51.

Colombini M. Turbulence-driven secondary flows and formation of sand ridges[J]. Journal of Fluid Mechanics, 1993, 254(1): 701-719.

Huthnance J M. On one mechanism forming linear sand banks[J]. Estuarine, Coastal and Shelf Science, 1982, 14(1): 79-99.

Langmuir I. Surface motion of water introduced by wind[J]. Science, 1938, 87:119-123.

Craik A D D. A wave-interaction model for the generation of windrows[J]. Journal of Fluid Mechanics, 1970, 41(4): 801-821.

Craik A D D, Leibovich S. A rational model for Langmuir circulations[J]. Journal of Fluid Mechanics, 1976, 73(3): 401-426.

李爽. Langmuir环流和波浪破碎对上层海洋混合影响的数值研究[D]. 青岛:中国科学院海洋研究所, 2010: 1-40.

Noh Y, Min H S, Raasch S. Large eddy simulation of the ocean mixed layer:The effects of wave breaking and Langmuir circulation[J].Journal of Physical Oceanography, 2004, 34(4): 720-735.

McWilliams J C, Sullivan P P, Moeng C H. Langmuir turbulence in the ocean[J]. Journal of Fluid Mechanics, 1997, 334: 1-30.

Skyllingstad E D, Denbo D W. An ocean large-eddy simulation of Langmuir circulations and convection in the surface mixed layer[J]. Journal of Geophysical Research, 1995, 100(C5): 8501-8522.

Leibovich S. The form and dynamics of Langmuir circulations[J]. Annual review of fluid mechanics, 1983, 15(1): 391-427.

Pollard R. Observations and theolies of Langmuir circulations and their role in near surface mixing[J]. A Voyage of Discovery: 1977, 70: 235-251.

Thorpe S A. Langmuir circulation[J]. Annual Review of Fluid Mechanics, 2004, 36: 55-79.

Smith J A. Observed growth of Langmuir circulation[J]. Journal of Geophysical Research, 1992, 97(C4): 5651-5664.

Thorpe S A. Spreading of floating particles by Langmuir circulation[J]. Marine Pollution Bulletin, 2009, 58(12): 1787-1791.

乔方利, 王关锁, 吕新刚, 等. 2008 与2010 年黄海浒苔漂移输运特征对比[J]. 科学通报, 2011, 56(18): 1470-1476.

Smith J A. Observations and theories of Langmuir circulation: a story of mixing[J]. Fluid Mechanics and the Environment: Dynamical Approaches, 2001: 295-314.

Guadayol Ò, Peters F. Analysis of wind events in a coastal area: a tool for assessing turbulence variability for studies on plankton[J]. Scientia Marina, 2006, 70(1): 9-20.

Thorpe S A. Langmuir circulation and the dispersion of oil spills in shallow seas[J]. Spill Science & Technology Bulletin, 2000, 6(3/4):213-223.

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