A numerical study on seasonal variations of the thermocline in the South China Sea based on the ROMS
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摘要: 基于ROMS模型,数值研究了南海温跃层的季节变化。模拟得到的水动力特征与以往研究一致:由于季风的存在,南海的环流在冬季是气旋式的,而在夏季是反气旋式的。模拟的温度剖面与航次观测数据的误差在海洋上层较小,表明模拟结果是合理的。根据温度垂向剖面的形状,分别定义了5种跃层类型(浅跃层、深跃层、混合跃层、双跃层和多跃层)。在冬季,东北季风盛行,大部分水深较浅的陆架海区域充分混合,跃层不明显,而深水区一般有深跃层存在,混合跃层和双跃层大多出现在南海南部冷涡附近。在夏季,西南季风盛行,具有浅跃层特征的陆架海区显著扩大。跃层分布与水深有一定关系,从浅水到深水呈现浅跃层-混合跃层-深跃层的变化规律,其中双跃层和多跃层多出现在水深梯度变化剧烈的海域。本文还讨论了跃层三要素(上界、厚度和强度)的季节变化特征。由于南海是台风频繁产生和经过的区域,本文还讨论了跃层对台风过程的短期响应。
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关键词:
- 温跃层,南海,ROMS,台风
Abstract: On the basis of the regional ocean modeling system (ROMS), the seasonal variations of the thermocline in the South China Sea (SCS) were numerically investigated. The simulated hydrodynamics are in accordance with previous studies: the circulation pattern in the SCS is cyclonic in winter and anticyclonic in summer, and such a change is mostly driven by the monsoon winds. The errors between the modeled temperature profiles and the observations obtained by cruises are quite small in the upper layers of the ocean, indicating that the ocean status is reasonably simulated. On the basis of the shapes of the vertical temperature profiles, five thermocline types (shallow thermocline, deep thermocline, hybrid thermocline, double thermocline, and multiple thermocline) are defined herein. In winter, when the northeasterly monsoon prevails, most shallow shelf seas in the northwest of the SCS are well mixed, and there is no obvious thermocline. The deep region generally has a deep thermocline, and the hybrid or double thermocline often occurs in the areas near the cold eddy in the south of the SCS. In summer, when the southwesterly monsoon prevails, the shelf sea area with a shallow thermocline greatly expands. The distribution of different thermocline types shows a relationship with ocean bathymetry: from shallow to deep waters, the thermocline types generally change from shallow or hybrid to deep thermocline, and the double or multiple thermocline usually occurs in the steep regions. The seasonal variations of the three major thermocline characteristics (the upper bound depth, thickness, and intensity) are also discussed. Since the SCS is also an area where tropical cyclones frequently occur, the response of thermocline to a typhoon process in a short time scale is also analyzed.-
Key words:
- thermocline
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Dale W L. 1956. Wind and drift current in the South China Sea. The Malayan Journal of Tropical Geography, 8: 1-31 Guan Bingxian. 1999. Phenomenon of the inversion thermocline in winter in the coastal water of the west of East China Sea and its relation to circulation. Journal of Oceanography of Huanghai & Bohai Seas (in Chinese), 17(2): 1-7 Haidvogel D B, Arango H, Budgell W P, et al. 2008. Ocean forecasting in terrain-following coordinates: formulation and skill assessment of the regional ocean modeling system. Journal of Computational Physics, 227: 3595-3624 Hao Jiajia, Chen Yongli, Wang Fan. 2010. Temperature inversion in China seas. J Geophys Res, 115: C12025, doi: 10.1029/2010JC006297 Hu Jianyu, Kawamura H, Hong Huasheng, et al. 2000. A review on the currents in the South China Sea: seasonal circulation, South China Sea Warm Current and Kuroshio intrusion. Journal of Oceanography, 56: 607-624 Lan Jian, Bao Ying, Yu Fei, et al. 2006. Seasonal variabilities of the circulation and thermocline depth in the South China Sea deep water basin. Advance in Marine Science (in Chinese), 24(4): 436-445 Li Peiliang, Qi Jianhua, Fang Xinhua. 2000. The characteristics of the sea water transition layer in the investigated area of Nansha Islands in Nov. 1997. Tansactions of Oceanology and Limnology (in Chinese), 1: 1-7 Li Rongfeng, Zeng Qingcun, Ji Zhongzhen, et al. 1992. Numerical simulation for a northeastward flowing current from area off the eastern Hainan Island to Tsugaru/Soya Strait. La Mer, 30: 229-238 Liu Guifang. 1989. Distribution characteristics of temperature, salinity and density in the continental shelf off east Guangdong during July 1987. Tropic Oceanology (in Chinese), 8(2): 39-47 Liu Qinyu, Jia Yinglai, Liu Penghui, et al. 2001. Seasonal and intraseasonal thermocline variability in the central South China Sea. Geophys Res Lett, 28(23): 4467-4470 Liu Qinyu, Yang Haijun, Wang Qi. 2000. Dynamic characteristics of seasonal thermocline in the deep sea region of the South China Sea. Chinese J Oceanol, 118(2): 104-109 Mao Hanli, Qiu Daoli. 1964. National Oceanic Comprehensive Survey Report: Thermocline, Halocline, Pycnocline Phenomena in China Coastal waters Waters (in Chinese). Beijing: China Science Press, 116 Pohlmann T. 1987. A three dimensional circulation model of the South China Sea. In: Nihoul J C J , Jamart B M, eds. Three-Dimensional Models of Marine and Estuarine Dynamics. New York: Elsevier, 245-268 Qiu Zhang, Cai Shuqun. 2000. Distribution characteristics of mean sea temperature relative to thermocline in deep water of Nansha Islands sea area. Tropic Oceanology (in Chinese), 19(4): 10-13 Shaw P T, Chao S Y. 1994. Surface circulation in the South China Sea. Deep-Sea Res Pt I, 40(11/12): 1663-1683 Sun Chengxue, Liu Qinyu. 2011. Double eddy structure of the winter Luzon cold eddy based on satellite altimeter data. Journal of Tropical Oceanography (in Chinese), 30(3): 9-15 Takano K, Harashima A, Namba T. 1998. A numerical simulation of the circulation in the South China Sea-Preliminary results. Acta Oceanogr Taiwanica, 37(2): 165-186 Wang Bin, Wu Renguang, Lukas R. 2000. Annual adjustment of the thermocline in the tropical Pacific Ocean. Journal of Climate, 13: 596-616 Yang Haijun, Liu Qinyu. 1998. The seasonal features of temperature distributions in the upper layer of the South China Sea. Oceanologia et Limnologia Sinica (in Chinese), 29(5): 501-507 Zhang Mengning, Liu Jinfang, Mao Kexiu, et al. 2006. The general distribution characteristics of thermocline of China Sea. Marine Forecasts (in Chinese), 23(4): 51-58 Zhou Faxiu, Ding Jie, Yu Shenyu. 1995. The intraseasonal oscillation of sea surface temperature in the South China Sea. Journal of Ocean University of Qingdao (in Chinese), 25(1): 1-6 Zhou Yanxia, Fan Zhenhua, Yan Wenbin, et al. 2004. Thermocline comparison of SCS using BT and Nansen data. Marine Science Bulletin (in Chinese), 23(1): 22-26
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