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FAN Wei,SONG Jinbao,LI Shuang. 2014. A numerical study on seasonal variations of the thermocline in the South China Sea based on the ROMS. Acta Oceanologica Sinica, 33(7):56-64
A numerical study on seasonal variations of the thermocline in the South China Sea based on the ROMS
基于ROMS模型数值研究南海温跃层的季节变化
Received:March 26, 2012  Revised:November 26, 2013
DOI:10.1007/s13131-014-0504-8
Key words:thermocline  South China Sea  ROMS  typhoon
中文关键词:  温跃层,南海,ROMS,台风
基金项目:The National Basic Research Program of China under contract Nos 2011CB403501 and 2012CB417402;the Fund for Creative Research Groups by National Natural Science Foundation of China under contract No. 41121064;the Knowledge Innovation Programs of the Chinese Academy of Sciences under contract No. KZCX2-YW-Q07-02.
Author NameAffiliationE-mail
FAN Wei Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China fanjieyu@163.com 
SONG Jinbao Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China  
LI Shuang Department of Ocean Science and Engineering, Zhejiang University, Hangzhou 310058, China  
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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.
中文摘要:
      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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