北太平洋西边界流研究综述

综述了近20年来国内外学者在研究北太平洋西边界流的平均结构及NEC分叉动力机制、NM K流系平均输运的分配及变化、NM K流系季节及年际变化规律及其与EN SO之间的关系、NM K流系在热带和亚热带水交换中的作用以及水团的平均分布特征等方面所取得的主要成果。通过分析,发现东亚季风、R ossby波和K e lv in波等是影响北太平洋西边界流的主要因素;而缺乏长期直接的海流观测资料是深入研究北太平洋西边界流遇到的最大障碍。

A summary on studies of western boundary current system in the North Pacific Ocean

The North Equatorial Current(NEC) in the Pacific Ocean bifurcates as it approaches the Phillippine coast,feeding the northward flowing Kuroshio and the southward flowing Mindanao Current(MC).The NEC-Kuroshio-MC current system is important because of its role in the heat budget of the western Pacific Ocean warmpool and its direct involvement in the global ocean thermocline circulation via the Indonesian throughflow,both of which are believed to be essential in determining the world's climate.Also,the current system is a part of the shallow,meridional,wind and buoyancy-flux-driven circulation that directly connects the subtropical and equatorial oceans.Studies of the current system have significantly advanced our knowledge of its mass and heat transport,in particular with regard to its variations.In this paper,we give a summary of the main studies on western boundary current system in the North Pacific Ocean in latest twenty years in order to get more completely understanding of its structure and variations.The NEC bifurcation is mainly controlled remotely by Rossby waves from the east,remotely by equatorward propagating coastal Kelvin-like waves from the north,and locally by the East Asian monsoon,in which the Asian monsoon is the most important factor deciding the seasonal variation of the NEC bifurcation.Special attentions should be paid on the following key problems,that is,the NEC bifurcation latitude, mean transport and its variability of the NMK current system,the seasonal and inter-annual variability of NEC bifurcation latitude,the relationship between the variability of NEC and ENSO,the role of the NMK current system in exchanging the tropical and subtropical water and the dynamic mechanism of the NEC bifurcation and the mean structure of the NMK current system.Though there are some difficulties such as short of data and no completely three dimensional numerical model with enough high resolution of the western boundary current system in the North Pacific Ocean in present research,it is still possible for us to understand the SCS circulation more clearly by further ocean investigation,four dimensional assimilation on all historical data,diagnostic analysis of physical mechanism with simple conceptual model and numerical experiment considering all sorts of physical processes.