西北太平洋副热带逆流、北赤道流、北赤道逆流几个特征的比较

A Comparison of Characteristics between the Subtropical Countercurrent, the North Equatorial Current and the North Equatorial Countercurrent in the Northwestern Pacific Ocean

根据 1 37°E断面 1 967～ 1 995年冬、夏季的温、盐资料 ,计算和分析该断面的地转流 ;分析 1 44°E断面上投放卫星跟踪漂流浮标的漂移轨迹 ;结合 CSK图集中的海面重力势分布 ,对副热带逆流、北赤道流和北赤道逆流几个特征的相同点和不同点进行比较 ,得出若干有益的结论 :( 1 )副热带逆流、北赤道流、北赤道逆流 ,并不是单纯的单支海流 ,而是存在着两支或多支现象 ;( 2 )流速结构的带状分布 ,东、西向流相互交错间隔出现 ,流层较浅 ,均为表层流或近表层流 ;( 3)多年平均而言 ,3支海流的流速以北赤道逆流最强 ,北赤道流次之 ,副热带逆流最弱 ;流量则不同 ,北赤道流最大 ,副热带逆流最小 ,北赤道逆流居中。 3支海流的流速夏季均大于冬季 ,但流量稍有差异 :副热带逆流和北赤道流均具有夏强、冬弱的特点 ,而北赤道逆流为冬强、夏弱 ;( 4 )冬季 ,副热带逆流的“源地”,位于巴士海峡和台湾以东“副热带脊”的一个“暖脊”中心附近海域 ;( 5)冬季 ,卫星跟踪漂流浮标的漂移轨迹 ,基本上反映出北赤道流和北赤道逆流的路径。但因副热带逆流区为涡旋频繁区 ,致使浮标漂移轨迹难以反映出副热带逆流的路径。

According to the geostrophic current calculated from the hydrographic data of temperature and salinity at section 137°E during the winters and summers of 1967～1995, the drift trajectories of drifting buoies which were deployed at 144°E observed by satellites and together with the distributions of surface geopotential anomaly obtained from CSK Atlas, a comparison of the similarities and dissimilarities of the characteristics between the Subtropical Countercurrent (SCC), the North Equatorial Current (NEC) and North Equatorial Countercurrent (NECC) in the Northwestern Pacific Ocean is made in this paper.The main results are concluded as follows: (1) The SCC, NEC and ENCC have the features of multi branch. (2) They all appear at the surface or subsurface with banded current structure, and the eastward and westward currents occurring alternatively. (3) In regard to annual mean velocity of these three currents, the NECC is the strongest current, the NEC is the next one and the SCC is the weakest one. However, the variations of their volume transports are quite different. The largest one is the NEC, the next one is the NECC and the smallest one is SCC. The current speed of three currents in summer is highev than that in winter, but the variations of their volume transports are little bit different, the volume transports of the SCC and the NEC are strong and weak in summer and in winter, respectively; those of the NECC are opposite. (4) During winter, the original area of the SCC is located at Bazel strait and near the center of 'Warm Ridge' of the subtropical ridge east of Taiwan Island. (5) The drift trajectories of satellite drifting buoies in winter basically show the paths of the NEC and the NECC, however, it is difficult to demonstrate the path of the SCC in the area where eddies occurred frequently