摘要
南海是西北太平洋最大的边缘海,是联系北太平洋和北印度洋的关键通道。黑潮北上经过吕宋海峡时会将来自西太平洋的信号传入南海,进而影响南海的水动力环境。研究了南海次表层盐度的空间分布特征、低频变化规律及其与太平洋年代际振荡(Pacific Decadal Oscillation, PDO)的关系,并进一步探究了次表层盐度近年来的变化。结果显示:1)南海次表层高盐水的位势密度主要介于24~26σθ,受次表层气旋式环流所驱动,盐度气候态空间分布北高南低,以吕宋海峡处为起点,呈逆时针自北向南逐渐降低。2)次表层盐度低频变化显著,与PDO呈显著的正相关关系。当PDO处于正位相时,吕宋海峡处西向平流输送加强,次表层盐度升高;当PDO处于负位相时,吕宋海峡处西向平流输送减弱,次表层盐度降低,盐度的变化受到水平环流场的直接影响。3)近年来,南海次表层盐度呈现先降低后升高再降低的趋势,滞后PDO约10个月, 2006—2014年初,盐度呈下降趋势;2014—2017年初,盐度呈上升趋势,且上升速率远大于先前下降的速率;2017年后盐度再次逐渐降低。
The South China Sea is the largest marginal sea in the northwestern Pacific and the key channel connecting the North Pacific and northern Indian Ocean.When the Kuroshio flows northward along the Philippine Islands,signals from the western Pacific are transmitted to the South China Sea through the Luzon Strait,thus affecting the hydrodynamic environment of the South China Sea.We analyze the spatial distribution and low-frequency variability of subsurface salinity in the South China Sea,and try to explain the relationship between the subsurface salinity in the South China Sea and the Pacific Decadal Oscillation(PDO);we also explore the change of the subsurface salinity in recent years.The results are as follows.1) Driven by the subsurface cyclonic circulation,subsurface salinity at about 24-26 σθ decreases gradually from north to south counterclockwise starting from the Luzon Strait.2) The low-frequency variability of subsurface salinity is significantly correlated with PDO.When the PDO is in the positive phase,the westward transport in the Luzon Strait is strengthened and the subsurface salinity increases.When the PDO is in the negative phase,the westward transport in the Luzon Strait is weakened and the subsurface salinity decreases,and the salinity change is directly affected by the horizontal circulation.3) In recent years,the subsurface salinity has shown a trend of refreshing from 2006 to early 2014,and then increasing from 2014 to early 2017,lagging behind the PDO by about 10 months.Since 2017,the salinity decreased again.
作者
王祥鹏
张玉红
王爱梅
赵玮
杜岩
WANG Xiangpeng;ZHANG Yuhong;WANG Aimei;ZHAO Wei;DU Yan(State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology,Chinese Academy of Sciences),Guangzhou 510301,China;University of Chinese Academy of Sciences,Beijing 100049,China;National Marine Data and Information Service,Tianjin 300100,China;College of Oceanic and Atmospheric Sciences,Ocean University of China,Qingdao 266100,China)
出处
《热带海洋学报》
CAS
CSCD
北大核心
2019年第4期1-9,共9页
Journal of Tropical Oceanography
基金
中国科学院战略性先导科技专项(XDA19060501、XDA13010404)
国家海洋局“全球变化与海气相互作用”专项(GASI-IPOV AI-02)
国家自然科学基金项目(41525019、41506019、41805057、41830538)~~
关键词
次表层盐度
低频变化
太平洋年代际振荡
平流输送
南海
subsurface salinity
low frequency variability
Pacific Decadal Oscillation(PDO)
advection
South China Sea
