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Li Dawei,Wei Zexun,Wang Yonggang,Li Shujiang,Xu Tengfei,Wang Guanlin,Teng Fei. 2019. Characteristics and temporal variations of near-bottom currents near the Dongsha Island in the northern South China Sea. Acta Oceanologica Sinica, 38(4):80-89
Characteristics and temporal variations of near-bottom currents near the Dongsha Island in the northern South China Sea
南海北部东沙岛附近海洋底层流场特征及时间变化规律
Received:June 20, 2018  
DOI:10.1007/s13131-019-1415-5
Key words:tidal currents  South China Sea  near-bottom currents  mesoscale eddies
中文关键词:  潮流  南海  底层流场  中尺度涡旋
基金项目:The National Key Research and Development Program of China under contract No. 2017YFC1404201; the National Natural Science Foundation of China under contract Nos 41706035 and 41876029; the NSFC-Shandong Joint Fund for Marine Science Research Centers under contract No. U1606405; the Laboratory for Regional Oceanography and Numerical Modeling, Qingdao National Laboratory for Marine Science and Technology under contract No. 2017A01; the China Postdoctoral Science Foundation under contract No. 2017M622111.
Author NameAffiliationE-mail
Li Dawei Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China 
 
Wei Zexun Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China 
weizx@fio.org.cn 
Wang Yonggang Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China 
 
Li Shujiang Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China 
 
Xu Tengfei Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China 
 
Wang Guanlin Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China 
 
Teng Fei Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China 
 
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Abstract:
      Near-bottom currents play important roles in the formation and dynamics of deep-water sedimentary systems. This study examined the characteristics and temporal variations of near-bottom currents, especially the tidal components, based on two campaigns (2014 and 2016) of in situ observations conducted southeast of the Dongsha Island in the South China Sea. Results demonstrated near-bottom currents are dominated by tidal currents, the variance of which could account for~70% of the total current variance. Diurnal tidal currents were found stronger than semidiurnal currents for both barotropic and baroclinic components. The diurnal tidal currents were found polarized with predominantly clockwise-rotating constituents, whereas the clockwise and counterclockwise constituents were found comparable for semidiurnal tidal currents. It was established that diurnal tidal currents could induce strong current shear. Baroclinic tidal currents showed pronounced seasonal variation with large magnitude in winter and summer and weak magnitude in spring and autumn in 2014. The coherent components accounted for~65% and~50% of the diurnal and semidiurnal tidal current variances, respectively. The proportions of the coherent and incoherent components changed little in different seasons. In addition to tidal currents, it was determined that the passing of mesoscale eddies could induce strong near-bottom currents that have considerable influence on the deep circulation.
中文摘要:
      海洋底层流场在海底沉积系统的形成及演变中起到了非常重要的作用。本文基于2014年和2016年的现场观测数据,研究了南海北部东沙岛附近海洋底层流场的特征及时间变化规律。研究结果表明底层流场的主要成分是潮流,潮流引起的流场变化占总流场变化的70%。无论是正压潮还是斜压潮,全日潮分量都大于半日潮分量。全日潮表现出明显的极化特征,顺时针成分远大于逆时针成分,而半日潮则没有这个特征。全日潮是引起底层流场剪切的主要因素。潮流表现出明显的季节变化特征,冬季和夏季强度较强,春季和秋季强度较弱。潮流中相干成分分别占全日潮和半日潮的65%和50%,相干成分所占比例没有明显的季节变化。除了潮流,中尺度涡旋的过境会明显增强底层流场强度,这对南海北部的深层环流具有重要影响。
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