Abstract
Multiple linear regression (MLR) method was applied to quantify the effects of the net heat flux (NHF), the net freshwater flux (NFF) and the wind stress on the mixed layer depth (MLD) of the South China Sea (SCS) based on the simple ocean data assimilation (SODA) dataset. The spatio-temporal distributions of the MLD, the buoyancy flux (combining the NHF and the NFF) and the wind stress of the SCS were presented. Then using an oceanic vertical mixing model, the MLD after a certain time under the same initial conditions but various pairs of boundary conditions (the three factors) was simulated. Applying the MLR method to the results, regression equations which modeling the relationship between the simulated MLD and the three factors were calculated. The equations indicate that when the NHF was negative, it was the primary driver of the mixed layer deepening; and when the NHF was positive, the wind stress played a more important role than that of the NHF while the NFF had the least effect. When the NHF was positive, the relative quantitative effects of the wind stress, the NHF, and the NFF were about 10, 6 and 2. The above conclusions were applied to explaining the spatio-temporal distributions of the MLD in the SCS and thus proved to be valid.
Similar content being viewed by others
References
Brainerd K E, Gregg M C. 1995. Surface mixed and mixing layer depths. Deep-Sea Research, 42(9): 1521–1543
Carton J A, Chepurin G, Cao X, et al. 2000. A simple ocean data assimilation analysis of the global upper ocean 1950–95. Part I: Methodology. J Phys Oceanogr, 30(2): 294–309
de Boyer Montégut C, Madec G, Fischer A S, et al. 2004. Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology. J Geophys Res, 109: C12003
Du Yan, Wang Dongxiao, Shi Ping, et al. 2004. Seasonal variation of the barrier layer in the South China Sea and its relationship to the sea surface flux. Chinese Journal of Atmospheric Sciences (in Chinese), 28(1): 101–111
Fan Conghui, Wang Juanjuan, Song Jinbao. 2010. Factors influencing the climatological mixed layer depth in the South China Sea: numerical simulations. Chinese Journal of Oceanology and Limnology, 28(5): 1112–1118
Gaspar P, Grégoris Y, Lefevre J M. 1990. A simple eddy kinetic energy model for simulations of the oceanic vertical mixing: Tests at station Papa and long-term upper ocean study site. J Geophys Res, 95(C9): 16179–16193
Kara A B, Rochford P A, Hurlburt H E. 2000. An optimal definition for ocean mixed layer depth. J Geophys Res, 105(C7): 16803–16821
Liu Zhiliang, Chu Zhongxin. 2007. Effects if Short-wave Solar Penetration Radiation on the Mixed Layer Depth. Transactions of Oceanology and Limnology (in Chinese), 2: 19–25
Liu Qinyu, Jia Xujing, Sun Jilin, et al. 2000. Dynamic features and formation mechanism of the upper mixed layer in the South China Sea before and after 1998 summer monsoon onset. Climatic and Environmental Research (in Chinese), 5(4): 469–481
Liu Qinyu, Sun Jilin, Jia Xujing. 2001. Numerical simulation and experiments of the upper mixed layer in the south of the South China Sea in spring. Journal of Ocean University of Qingdao (in Chinese), 31(2): 149–157
Liu Qinyu, Sun Jilin, Jia Xujing. 2002. Numerical simulation and experiments of the upper mixed layer in the northern South China Sea in spring. Oceanologia et Limnologia Sinica (in Chinese), 33(5): 526–535
McCreary Jr J P, Kohler K E, Hood R R, et al. 2001. Influences of diurnal and intraseasonal forcing on mixed-layer and biological variability in the central Arabian Sea. J Geophys Res, 106(C4): 7139–7155
Obata A, Ishizaka J, Endoh M. 1996. Global verification of critical depth theory for phytoplankton bloom with climatological in situ temperature and satellite ocean color data. J Geophys Res, 101(C9): 20657–20667
Qu Tangdong. 2001. Role of ocean dynamics in determining the mean seasonal cycle of the South China Sea surface temperature. J Geophys Res, 106(C4): 6943–6955
Qu Tangdong, Du Yan, Gan Jianping, et al. 2007. Mean seasonal cycle of isothermal depth in the South China Sea. J Geophys Res, 112(C2): C02020
Rao R R, Molinari R L, Festa J F. 1989. Evolution of the climatological near-surface thermal structure of the tropical Indian Ocean 1. Description of mean monthly mixed layer depth, and sea surface temperature, surface current, and surface meteorological fields. J Geophys Res, 94(C8): 10801–10815
Shi Ping, Du Yan, Wang Dongxiao, et al. 2001. Annual cycle of mixed layer in South China Sea. Journal of Tropical Oceanography (in Chinese), 20(1): 10–17
Sprintall J, Roemmich D. 1999. Characterizing the structure of the surface layer in the Pacific Ocean. J Geophys Res, 104(C10): 23297–23311
Suga T, Motoki K, Aoki Y, et al. 2004. The North Pacific climatology of winter mixed layer and mode waters. Journal of Physical Oceanography, 34(1): 3–22
Sun Chengxue, Liu Qinyu, Jia Yinglai. 2007. Annual and interannual variations of the mixed layer in the South China Sea. Periodical of Ocean University of China (in Chinese), 37(2): 197–203
Weller R A, Fischer A S, Rudnick D L, et al. 2002. Moored observations of upper-ocean response to the monsoons in the Arabian Sea during 1994–1995. Deep-Sea Research, 49(12): 2195–2230
Yan Youfang, Gan Zijun, Qi Yiquan. 2006. Buoyancy flux, water type conversion and warm water variation of surface sea water in South China Sea. Journal of Tropical Oceanography (in Chinese), 25(5): 1–7
Yang Haijun, Liu Qinyu, Liu Zhengyu, et al. 2002. A general circulation model study of the dynamics of the upper ocean circulation of the South China Sea. J Geophys Res, 107(C7): 3085
Zeng Lili, Wang Dongxiao. 2009. Intraseasonal variability of latent-heat flux in the South China Sea. Theoretical and Applied Climatology, 97(1): 53–64
Zhuang Wei, Wang Dongxiao, Hu Jianyu, et al. 2006. Response of the cold water mass in the western South China Sea to the wind stress curl associated with the summer monsoon. Acta Oceanologica Sinica, 25(4): 1–13
Zhuang Wei, Xie Shangping, Wang Dongxiao, et al. 2010. Intraseasonal variability in sea surface height over the South China Sea. J Geophys Res, 115(C4): C04010
Author information
Authors and Affiliations
Corresponding author
Additional information
Foundation item: The National Natural Science Foundation of China under contract No. 11174235; the Science and Technology Development Project of Shaanxi Province of China under contract No. 2010KJXX-02; the Program for New Century Excellent Talents in University of China under contract No. NCET-08-0455; the Science and Technology Innovation Foundation of Northwestern Polytechnical University of China; the Doctorate Foundation of Northwestern Polytechnical University of China under contract No. CX201226.
Rights and permissions
About this article
Cite this article
Duan, R., Yang, K., Ma, Y. et al. A study of the mixed layer of the South China Sea based on the multiple linear regression. Acta Oceanol. Sin. 31, 19–31 (2012). https://doi.org/10.1007/s13131-012-0250-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13131-012-0250-8