Abstract
The turbulent mixing in the upwelling region east of Hainan Island in the South China Sea is analyzed based on in situ microstructure observations made in July 2012. During the observation, strong upwelling appears in the coastal waters, which are 3°C cooler than the offshore waters and have a salinity 1.0 greater than that of the offshore waters. The magnitude of the dissipation rate of turbulent kinetic energy ε in the upwelling region is O (10–9 W/kg), which is comparable to the general oceanic dissipation. The inferred eddy diffusivity Kρ is O (10–6 m2/s), which is one order of magnitude lower than that in the open ocean. The values are elevated to Kρ≈O (10–4 m2/s) near the boundaries. Weak mixing in the upwelling region is consistent with weak instability as a result of moderate shears versus strong stratifications by the joint influence of surface heating and upwelling of cold water. The validity of two fine-scale structure mixing parameterization models are tested by comparison with the observed dissipation rates. The results indicate that the model developed by MacKinnon and Gregg in 2003 provides relatively better estimates with magnitudes close to the observations. Mixing parameterization models need to be further improved in the coastal upwelling region.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
Allen J S. 1980. Models of wind-driven currents on the continental shelf. Annual Review of Fluid Mechanics, 12: 389–433
Allen J S, Newberger P A, Federiuk J. 1995. Upwelling circulation on the Oregon continental shelf Part I Response to idealized forcing. Journal of Physical Oceanography, 25(8): 1843–1866
Avicola G S, Moum J N, Perlin A, et al. 2007. Enhanced turbulence due to the superposition of internal gravity waves and a coastal upwelling jet. Journal of Geophysical Research, 112(C6): C06024, doi: 10.1029/2006JC003831
Carter G S, Gregg M C, Lien R C. 2005. Internal waves, solitary-like waves, and mixing on the Monterey Bay shelf. Continental Shelf Research, 25(12–13): 1499–1520
Davies A M, Xing Jiuxing. 2003. Processes influencing wind-induced current profiles in near coastal stratified regions. Continental Shelf Research, 23(14–15): 1379–1400
De Szoeke R A, Richman J G. 1981. The role of wind-generated mixing in coastal upwelling. Journal of Physical Oceanography, 11(11): 1534–1547
Djurfeldt L. 1989. Circulation and mixing in a coastal upwelling embayment; Gulf of Arauco, Chile. Continental Shelf Research, 9(11): 1003–1016
Guan Bingxian, Chen Shangji. 1964. Cruise report of General Oceanographic Survey of Bohai Sea, Yellow Sea, East China Sea and South China Sea (in Chinese). Qingdao: Institute of Oceanography, Chinese Academy of Science
Gregg M C. 1989. Scaling turbulent dissipation in the thermocline. Journal of Geophysical Research, 94(C7): 9686–9698
Gregg M C, Sanford T B, Winkel D P. 2003. Reduced mixing from the breaking of internal waves in equatorial waters. Nature, 422(6931): 513–515
Hales B, Moum J N, Covert P, et al. 2005a. Irreversible nitrate fluxes due to turbulent mixing in a coastal upwelling system. Journal of Geophysical Research, 110(C10): C10S11, doi: 10.1029/2004JC002685
Hales B, Takahashi T, Bandstra L. 2005b. Atmospheric CO2 uptake by a coastal upwelling system. Global Biogeochemical Cycles, 19(1): GB1009, doi: 10.1029/2004GB002295
Han Wuying, Wang Mingbiao, Ma Kemei. 1990. On the lowest surface water temperature area of China sea in summer–the upwelling along the east coast of Hainan Island. Oceanologia et Limnologia Sinica (in Chinese), 21(3): 267–275
Howard L N. 1961. Note on a paper of John W. Miles. Journal of Fluid Mechanics, 10(4): 509–512
Jing Zhiyou, Qi Yiquan, Du Yan. 2011. Upwelling in the continental shelf of northern South China Sea associated with 1997–1998 El Niño. Journal of Geophysical Research, 116(C2): C02033, doi: 10.1029/2010JC006598
Jing Zhiyou, Qi Yiquan, Hua Zulin, et al. 2009. Numerical study on the summer upwelling system in the northern continental shelf of the South China Sea. Continental Shelf Research, 29(2): 467–478
Kundu P K, Beardsley R C. 1991. Evidence of a critical Richardson number in moored measurements during the upwelling season off northern California. Journal of Geophysical Research, 96(C3): 4855–4868
Kunze E, Firing E, Hummon J M, et al. 2006. Global abyssal mixing inferred from lowered ADCP shear and CTD strain profiles. Journal of Physical Oceanography, 36(8): 1553–1576
Li Li. 1993. Summer upwelling system over the northern continental shelf of the South China Sea: a physical description. In: Su J, Chuang W S, Hsueh R Y, eds. Proceedings of the Symposium on the Physical and Chemical Oceanography of the China Seas. Beijing, China: China Ocean Press, 58–68
Lin Peigen, Cheng Peng, Gan Jianping, et al. 2016. Dynamics of winddriven upwelling off the northeastern coast of Hainan Island. Journal of Geophysical Research, 121(2): 1160–1173, doi: 10.1002/2015JC011000
Liu Junliang, Cai Shuqun, Wang Sheng’an. 2010. Currents and mixing in the northern South China Sea. Chinese Journal of Oceanology and Limnology, 28(5): 974–980
Liu Zhiyu, Wei Hao, Lozovatsky I D, et al. 2009. Late summer stratification, internal waves, and turbulence in the Yellow Sea. Journal of Marine Systems, 77(4): 459–472
Lu Zhumin, Chen Guiying, Xie Xiaohui, et al. 2009. The research of the micro-scale characteristic of the ocean mixing in the northern South China Sea in the summer. Progress in Nature Science (in Chinese), 19(6): 657–663
MacKinnon J A, Gregg M C. 2003. Mixing on the late-summer New England shelf-Solibores, shear, and stratification. Journal of Physical Oceanography, 33(7): 1476–1492
Matsuno T, Wolk F. 2005. Observations of turbulent energy dissipation rate ε in the Japan Sea. Deep Sea Research Part II: Topical Studies in Oceanography, 52(11–13): 1564–1579
Miles J W. 1961. On the stability of heterogeneous shear flows. Journal of Fluid Mechanics, 10(4): 496–508
Moum J N, Gregg M C, Lien R C, et al. 1995. Comparison of turbulence kinetic energy dissipation rate estimates from two ocean microstructure profilers. Journal of Atmospheric and Oceanic Technology, 12(2): 346–366
Osborn T R. 1980. Estimates of the local rate of vertical diffusion from dissipation measurements. Journal of Physical Oceanography, 10(1): 83–89
Palmer M R, Polton J A, Inall M E, et al. 2013. Variable behavior in pycnocline mixing over shelf seas. Geophysical Research Letters, 40(1): 161–166
Palmer M R, Rippeth T P, Simpson J H. 2008. An investigation of internal mixing in a seasonally stratified shelf sea. Journal of Geophysical Research, 113(C12): C12005, doi: 10.1029/2007JC004531
Pelegri J L, Richman J G. 1993. On the role of shear mixing during transient coastal upwelling. Continental Shelf Research, 13(12): 1363–1400
Schafstall J, Dengler M, Brandt P, et al. 2010. Tidal-induced mixing and diapycnal nutrient fluxes in the Mauritanian upwelling region. Journal of Geophysical Research, 115(C10): C10014, doi: 10.1029/2009JC005940
Smith R L. 1995. The physical processes of coastal ocean upwelling systems. In: Summerhayes C P, Emeis K C, Angel M V, et al., eds. Upwelling in the Ocean: Modern Processes and Ancient Records. New York: Wiley, 39–64
Su Jian, Pohlmann T. 2009. Wind and topography influence on an upwelling system at the eastern Hainan coast. Journal of Geophysical Research, 114(C6): C06017, doi: 10.1029/2008JC005018
Van Haren H, Maas L, Zimmerman J T F, et al. 1999. Strong inertial currents and marginal internal wave stability in the central North Sea. Geophysical Research Letter, 26(19): 2993–2996
Wang Jianing, Greenan B J W, Lu Youyu, et al. 2014. Layered mixing on the New England shelf in summer. Journal of Geophysical Research, 119(9): 5776–5796
Wang Yu, Jing Zhiyou, Qi Yiquan. 2016. Coastal upwelling off eastern Hainan Island observed in the summer of 2013. Journal of Tropical Oceanography (in Chinese), 35(2): 40–49
Wang Dakui, Wang Hui, Li Ming, et al. 2013. Role of Ekman transport versus Ekman pumping in driving summer upwelling in the South China Sea. Journal of Ocean University of China, 12(3): 355–365
Wolk F, Yamazaki H, Seuront L, et al. 2002. A new free-fall profiler for measuring biophysical microstructure. Journal of Atmospheric and Oceanic Technology, 19(5): 780–793
Wu Risheng, Li Li. 2003. Summarization of study on upwelling system in the South China Sea. Journal of Oceanography in Taiwan Strait (in Chinese), 22(2): 269–277
Xie Lingling, Guo Xinshun, Zhang Yanwei, et al. 2013. Reference velocity from bottom track in LADCP data processing. Ocean Technology (in Chinese), 32(2): 1–5, 34
Xie Lingling, Pallàs-Sanz E, Zheng Quanan, et al. 2017. Diagnosis of 3D vertical circulation in the upwelling and frontal zones east of Hainan Island, China. Journal of Physical Oceanography, 47(7): 755–774
Xie Shangping, Xie Qiang, Wang Dongxiao, et al. 2003. Summer upwelling in the South China Sea and its role in regional climate variations. Journal of Geophysical Research, 108(C8): 3261, doi: 10.1029/2003JC001867
Xie Lingling, Zhang Shuwen, Zhao Hui. 2012. Overview of studies on Qiongdong upwelling. Journal of Tropical Oceanography (in Chinese), 31(4): 35–41
Xie Lingling, Zong Xiaolong, Yi Xiaofei, et al. 2016. The interannual variation and long-term trend of Qiongdong upwelling. Oceanologia et Limnologia Sinica (in Chinese), 47(1): 43–51
Xiong Wuyi, Zhou Jiafa, Zhuo Mingxin, et al. 2000. Military Dictionay (in Chinese). Beijing: The Great Wall Press
Yang Shaolei, Xie Lingling, Yang Qingxuan. 2008. Field calibration and data-processing of SBE911plus CTD profiler. Ocean Technology (in Chinese), 27(3): 23–26, 30
Yin Jianqiang, Huang Liangmin, Li Kaizhi, et al. 2011. Abundance distribution and seasonal variations of Calanus sinicus (Copepoda: Calanoida) in the northwest continental shelf of South China Sea. Continental Shelf Research, 31(14): 1447–1456
Yu Wenquan. 1987. A preliminary approach of the upwelling for the northern South China Sea (in Chinese). Marine Sciences, 6(11): 7–10
Zhang Xiaoqian, Liang Xinfeng, Tian Jiwei. 2005. Estimates of mixing on the South China Sea shelf. Acta Oceanologica Sinica, 24(3): 1–8
Zhang Shuwen, Xie Lingling, Cao Ruixue, et al. 2012. Observation of upper-ocean mixing in the region west of the luzon strait in spring. Journal of Coastal Research, 28(5): 1208–1213
Zheng Zhewen, Zheng Quanan, Kuo Yichun, et al. 2016. Impacts of coastal upwelling off east Vietnam on the regional winds system: an air-sea-land interaction. Dynamics of Atmospheres and Oceans, 76: 105–115
Acknowledgements
The authors thank the crews of the R/V Tianlong for help with cruise measurements. The wind data are downloaded from the European Center for Medium-range Weather Forecasts (ECMWF, https://doi.org/apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc/). The SST data are downloaded from the Group for High-Resolution Sea Surface Temperature (GHRSST, https://doi.org/data.nodc.noaa.gov/ghrsst/L4/GLOB/UKMO/OSTIA/).
Author information
Authors and Affiliations
Corresponding author
Additional information
Foundation item: The National Natural Science Foundation of China under contract Nos 41476009, 41776034 and 41476010; the Natural Science Foundation of Guangdong Province of China under contract No. 2016A030312004; the Global Air-Sea Interaction Project of State Oceanic Administration under contract No. GASI-IPOVAI-01-02; the Laboratory of Tropical Ocean Open Foundation under contract No. LT1404.
Rights and permissions
About this article
Cite this article
Li, M., Xie, L., Zong, X. et al. The cruise observation of turbulent mixing in the upwelling region east of Hainan Island in the summer of 2012. Acta Oceanol. Sin. 37, 1–12 (2018). https://doi.org/10.1007/s13131-018-1260-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13131-018-1260-y