Two Key Mechanisms of Large-Scale Cross-Shelf Penetrating Fronts in the East China Sea: Flow Convergence and Thermocline Undulation

doi:10.1029/2022JC019075

IOCAS-IR > 海洋环流与波动重点实验室

	Two Key Mechanisms of Large-Scale Cross-Shelf Penetrating Fronts in the East China Sea: Flow Convergence and Thermocline Undulation
	He, Zhiwei1,2,3,4 ; Yang, Dezhou 1,3,4,5,6; Yin, Baoshu 1,3,4,5,6; Wu, Hui 7
	2024-02-01
发表期刊	JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
ISSN	2169-9275
卷号	129 期号:2 页码:33
通讯作者	Yang, Dezhou(yangdezhou@qdio.ac.cn)
摘要	Cross-shelf penetrating fronts (CPFs) induce significant cross-shelf exchange of water properties and nutrients, and thus are important to coastal environments. In this study, the characteristics and mechanisms of realistic large-scale CPFs in the East China Sea in summer were investigated based on a data assimilative model. The model reproduced CPFs matched well with satellite observations. Although the cross-shelf currents were predominantly offshore off the Zhe-Min Coast, only three strong large-scale CPFs occurred in the summer of 2014. The three-dimensional structure of CPF in the model was similar with that observed in previous research. Two different mechanisms were responsible for the formation of observed CPFs. Two CPFs formed as a result of the convergence of the Taiwan Warm Current (TWC) and the Zhe-Min Coastal Current (ZMCC), while the other one was caused by the undulation of thermocline. Heat budget analysis suggests that the undulation of thermocline was caused by horizontal and vertical advection. Sensitivity experiments suggest that southerly wind relaxation and tidal forcing are indispensable conditions for CPF formation. Tidal forcing makes the axis of the ZMCC shift offshore by similar to 50 km, so that the ZMCC could impinge right against the axis of the TWC. The relaxation of the southerly winds allows the ZMCC to extend southward. Southerly wind relaxation in summer is mostly associated with tropical cyclones. Without winds and synoptic variation of the TWC, CPFs form periodically due to the strengthening of the ZMCC during neap tide period. Coastal ocean currents generally follow isobaths on timescale longer than one day. Cross-shelf currents induce significant exchange of nutrients and dissolved materials and thus are important to coastal environments. Cross-shelf penetrating fronts are observed as large-distance cross-shelf frontal intrusion from satellite ocean-color observations. They frequently occurred in the East China Sea, but their key mechanisms are not very clear. Based on results of a numerical ocean model, we investigated several realistic cases of penetrating fronts in the summer of 2014 and revealed two major mechanisms. One mechanism is the convergence of two ocean currents that flow in the opposite direction. The other mechanism is associated with the thermocline undulation, which will induce cross-shelf currents through dynamic adjustment. The impact of several important factors which include tide forcing, winds, synoptic variation of shelf currents and river discharge were also evaluated with numerical experiments. The results show that tidal forcing and the relaxation of southerly winds are indispensable condition for penetrating fronts. The relaxation of southerly winds in summer is usually associated with the influence of typhoons. The revealed mechanisms advance our understanding of cross-shelf currents in coastal seas. Flow convergence and thermocline undulation are two major mechanisms of the penetrating fronts Tidal forcing and relaxation of southerly wind are indispensable conditions for penetrating front formation The relaxation of southerly winds in summer is mostly associated with tropical cyclones
关键词	cross-shelf penetrating fronts data assimilative model East China Sea flow convergence thermocline undulation
DOI	10.1029/2022JC019075
收录类别	SCI
语种	英语
资助项目	National Natural Science Foundation of China ; National Key Research and Development Program of China[2022YFC3004200] ; Strategic Priority Research Program of the Chinese Academy of Sciences[XDB42000000] ; Strategic Priority Research Program of the Chinese Academy of Sciences[XDA19060203] ; Strategic Priority Research Program of the Chinese Academy of Sciences[XDA19060202] ; NSFC-Shandong Joint Fund for Marine Science Research Centers[U1806227] ; Laoshan Laboratory (Qingdao)[LSKJ202202504] ; Laoshan Laboratory (Qingdao)[LSKJ2022020103] ; CAS-CSIRO BAU project[133137KYSB20180141] ; Key Deployment Project of Center for Ocean Mega-Research of Science, Chinese Academy of Science[COMS2020Q01] ; High Performance Computing Center at the IOCAS ; [92158202] ; [41876019] ; [42076022]
WOS研究方向	Oceanography
WOS类目	Oceanography
WOS记录号	WOS:001159783900001
出版者	AMER GEOPHYSICAL UNION
WOS关键词	YANGTZE-RIVER ESTUARY ; MODELING SYSTEM ROMS ; TAIWAN WARM CURRENT ; INTERANNUAL VARIABILITY ; DATA ASSIMILATION ; CHLOROPHYLL-A ; FRESH-WATER ; SURFACE ; GULF ; INTRUSION
引用统计
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/184466
专题	海洋环流与波动重点实验室海洋生态与环境科学重点实验室
通讯作者	Yang, Dezhou
作者单位	1.Chinese Acad Sci, Inst Oceanol, CAS Key Lab Ocean Circulat & Waves, Qingdao, Peoples R China 2.Qingdao Joint Inst Marine Meteorol, Qingdao, Peoples R China 3.Laoshan Lab, Qingdao, Peoples R China 4.Univ Chinese Acad Sci, Beijing, Peoples R China 5.Chinese Acad Sci, Ctr Ocean Mega Sci, Qingdao, Peoples R China 6.Chinese Acad Sci, Inst Oceanol, CAS Engn Lab Marine Ranching, Qingdao, Peoples R China 7.East China Normal Univ, State Key Lab Estuarine & Coastal Res, Shanghai, Peoples R China
第一作者单位	中国科学院海洋研究所
通讯作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	He, Zhiwei,Yang, Dezhou,Yin, Baoshu,et al. Two Key Mechanisms of Large-Scale Cross-Shelf Penetrating Fronts in the East China Sea: Flow Convergence and Thermocline Undulation[J]. JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,2024,129(2):33.
APA	He, Zhiwei,Yang, Dezhou,Yin, Baoshu,&Wu, Hui.(2024).Two Key Mechanisms of Large-Scale Cross-Shelf Penetrating Fronts in the East China Sea: Flow Convergence and Thermocline Undulation.JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,129(2),33.
MLA	He, Zhiwei,et al."Two Key Mechanisms of Large-Scale Cross-Shelf Penetrating Fronts in the East China Sea: Flow Convergence and Thermocline Undulation".JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS 129.2(2024):33.