海流（ocean current）海水在大范围里相对稳定的流动。既有水平，又有铅直的三维流动，是海水运动的普遍形式之一。“大范围”是指海流的空间尺度大，可在几千千米甚至全球范围内流动；“相对稳定”是指海流的路径、速率和方向，在数月、一年甚至多年的较长时间里保持一致。一般将发生在大洋里的海流称为洋流。
Ocean current is the relatively stable flow of seawater in a large scale. The three-dimensional flow which is shown in horizontal and vertical ways is one of the common forms of seawater movement. The term “large-scale” refers to the large space of the movement of ocean currents, which can flow over thousands of kilometers or even globally; “relatively stable” refers to the path, rate, and direction of ocean currents remain stable over months, one year or even years. The currents that occur in the oceans are generally referred to ocean currents.
基本概念
Basic Concept
海流又称洋流，是海水因热辐射、蒸发、降水、冷缩等而形成密度不同的水团，再加上风应力、地转偏向力、引潮力等作用而大规模相对稳定的流动，它是海水的普遍运动形式之一。海洋里有着许多海流，每条海流终年沿着比较固定的路线流动。它象人体的血液循环一样，把整个世界大洋联系在一起，使整个世界大洋得以保持其各种水文、化学要素的长期相对稳定。
Current, also called ocean current, is a large scale and relatively stable flow of seawater due to the formation of water masses with different densities by thermal radiation, evaporation, precipitation, and cold shrinkage, plus wind stress, coriolis force, and tidal attraction force, etc. It is one of the common forms of seawater movement. There are many currents in the ocean, and each current flows along a relatively fixed route throughout years. The current is like the blood circulation of the human body, linking the oceans in the whole world together, so that all oceans can maintain the long-term relative stability of its various hydrological and chemical elements.
海流，现代海洋学术语，又名“洋流”，古称“洋”，洋字从水从羊，“水”指水流、水体，“羊”意为“驯顺”。“水”与“羊”联合起来表示“像羊群顺走般流淌的水”，特指大海中浩荡的海流，亘古以来从不逆反，像羊群一般驯顺，可供水手驾驭、利用。
Current, a modern oceanographic term, also known as “ocean current”, was called “ocean” in ancient times. As to the Chinese character of “ocean”, it consists of elements of “water” and “sheep” in English. “Water” refers to water flow or water bodies, and “sheep” means “tame”. When “water” and “sheep” combine, the result means “the water flows like a flock of tame sheep”, specifically referring to the vast currents in the sea which have never been disastrous since ancient times and can be harnessed and utilized by seamen like a flock of sheep.
海流分类
Categories of Currents
海流按其水温低于或高于所流经的海域的水温，可分为寒流和暖流两种，前者来自水温低处，后者来自水温高处。表层海流的水平流速从几厘米/秒到300厘米/秒，深处的水平流速则在10厘米/秒以下。铅直流速很小，从几厘米/天到几十厘米/时。海流以流去的方向作为流向，恰和风向的定义相反。
Sea currents, according to its water temperature being lower or higher than that of the sea through which it flows, can be divided into cold currents and warm currents. The former is from the areas of low-water temperature, and the latter is from the areas of high-water temperature. The horizontal flow velocity of surface currents ranges from a few centimeters/second to 300 centimeters/second, while that in deep sea is below 10 centimeters/second. However, the flow velocity of vertical currents is low, ranging from a few centimeters/day to tens of centimeters/hr. The direction of currents is the direction of flow, exactly opposite to the definition of wind direction.
各地海流
Currents by Location
黑潮是太平洋地区最强的海流，因水色深蓝，看起来似黑色而得名。相对于它所流经的海域来讲，具有高温、高盐的特征，故有黑潮暖流之称。它起源于台湾东南、巴布延群岛以东海域，是北赤道流向北的一个分支的延伸。主流沿台湾东岸北上，经苏澳—与那国岛间的水道进入东海；然后沿东海大陆架边缘与大陆坡毗连区域流向东北，至奄美大岛以西约北纬29°、东经128°附近开始分支，主流折向东，经吐噶喇和大隅海峡离开东海返回太平洋，沿日本南岸向东北至北纬35°附近。
Kuroshio is the strongest current in the Pacific Ocean, named after its dark blue color. It is called the Kuroshio Current because of its high temperature and high salinity compared to the sea it flows through. It originates in the sea southeast of Taiwan and east of the Babuyan Islands, and is an extension of a branch of the North Equatorial Current to the north. The main current flows northward along the east coast of Taiwan and enters the East China Sea through the waterway between Suao and Yonagunijima; then it flows northeastward along the edge of the continental shelf of the East China Sea and the area adjacent to the continental slope and starts to branch off in the west of Amami Great Island (about 29°N, near 128°E). Its main current turns eastward and leaves the East China Sea through Tokara and Osumi-kaikyo to return to the Pacific Ocean, and then flows northeastward along the south coast of Japan to the area near 35°N.
指出现在长江口以南和浙闽近海，终年具有高温、高盐特征的海流。它自黑潮主干在台湾东北海域分出后，沿东海大陆架底坡北上，沿途受海底地形影响，流速逐渐减弱，约0.5节。该海流除表面易受季风影响外，中、下层的流向比较稳定，终年向北。其前锋在长江口外与南下的沿岸水混合，然后折向东北，其中一部分海水汇入对马暖流，另一部分汇入黄海暖流。夏季西南季风盛行时，迫使海水离岸输送，这时台湾暖流与沿岸流同向，两者汇成一片，流幅宽而势力强，几乎遍及东海西部的浅水区，流速0.3～0.4节，冬季东北风盛行时，迫使海水向岸输送，暖流方向与沿岸流方向相反，此时台湾暖流势力减弱，流幅变窄，流速0.1～0.3节。浙江近海的暖流和沿岸流之间形成明显的锋面，锋面以西为沿岸流南下，以东为暖流北上。
It is a current with high temperature and high salinity all year round, which is now in the south of the mouth of the Yangtze River and offshore Zhejiang and Fujian. It is divided from the main stem of the Kuroshio in the northeastern waters of Taiwan and goes northward along the bottom slope of the continental shelf of the East China Sea, and the flow speed gradually decreases by 0.5 knots along the way due to the influence of the submarine topography. The current is susceptible to the monsoon on the surface, except for the middle and lower layers, where the flow is relatively stable and northward all year round. Its front mixes with the southward coastal water outside the mouth of the Yangtze River, and then bends to the northeast where part of the seawater converges into the Tsushima Warm Current and the other part into the Yellow Sea Warm Current. In summer when the southwest monsoon prevails, seawater is forced to be transported offshore, then the Taiwan warm current and the coastal current flow in the same direction, and the two converge into one with a wide width and strong force, almost throughout the shallow water in the western part of the East China Sea with a flow speed of 0.3 to 0.4 knots; in winter when the northeast wind prevails, seawater is forced to be transported to the shore, and the direction of the warm current is opposite to the direction of the coastal current, and the Taiwan warm current weakens and the flow width becomes narrower with a flow speed of 0.1 to 0.3 knots at that time. There is a clear front between the warm current and the coastal current in offshore Zhejiang, with the coastal current flowing south to the west and the warm current flowing north to the east.
参考资料
《中国大百科全书》总编委会．《中国大百科全书》．《中国大百科全书》出版社．2009
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