Monthly variation of surface currents in the tropical Atlantic derived from TOPEX/Poseidon altimeter data
- 海洋环境－已发表论文 
应用1993年4月至2001年3月的TOPEX/Poseidon卫星高度计遥感资料,分析了8a平均热带大西洋(15°S～25°N,5°～50°W)表层环流结构的月变化特征.研究结果表明:热带大西洋表层环流中高纬度海区流速较小,赤道附近流速较大,表层环流系统大部分流系月变化不明显,部分流系月际波动较显著.具体来说,西南向的北赤道流下半年的纬向流速分量比上半年大.非洲沿岸流在5～11月流向为东北向,在其他月份主要为东南向.北赤道逆流可以分成两部分:25°W以东海区,北赤道逆流常年流向向东,到9月份前后流速达到最大值(约0 25cm/s);25°W以西海区,7月至翌年1月流向向东,2～6月北赤道逆流减小,并有西向流产生.2°S～2°N,15°W以东海区的南赤道流在1～3月、9～10月流向向东,其他月份流向向西.南赤道流可认为是由南、北两支西向的海流构成,这两支海流的流轴分别位于6°S和1°N,在6～7月北支流速达到最大值0 6m/s.南美洲纳塔耳东部西北向的北巴西海流流速月际变化不大,在5～6月份流速达到最大值0 3～0 4m/s.相应的卫星风场遥感资料的分析表明热带大西洋表层环流结构的月变化特征与风场的分布及变化有较好的对应关系.用WorldOceanAtlas2001的月平均温盐数据反演出来的表层地转流场以及卫星跟踪ARGOS漂流浮标观测进行的对比验证表明,The monthly variation of surface currents in the tropical Atlantic is studied by using the TOPEX/Poseidon altimeter data from April 1993 to March 2001. The results are as follow:The current is stronger in the low latitude of the tropical Atlantic Ocean than that in the high latitude of the tropical Atlantic Ocean. Although there are regions with a strong monthly variation of the tropical surface circulation, large regions of the tropics do not show a significant monthly variation. The zonal current in the North Equatorial Current region in July-December is greater than that in January-June. From May to November, the African Coastal Current is northeastward, while during the other months the velocity is southeastward. The North Equatorial Countercurrent is divided into two parts: East of 25°W the countercurrent continued throughout the year, and the maximum average velocity is about 25 cm/s in September. West of 25°W, from February to June the countercurrent diminishes and westward currents are observed, while during the other months, the countercurrent is eastward. The South Equatorial Current at 2°S～2°N, 15°～5°W change direction form east to west several times a year. During January, February, March, September and October the velocities are eastward. In the other months, the velocities are westward. The South Equatorial Current contains two currents, centered near 6°S and 1°N, the northern jet reaches the maximum 0.6 m/s in June through July. The North Brazil Current is stable, the maximum velocity of it is 0.3～0.4 m/s in May. The analysis of the wind data from ERS shows that the monthly changes of the circulation in the tropical Atlantic are well associated with the monthly signal of the wind field in the tropical Atlantic.The result from TOPEX/Poseidon is verified by the result from World Ocean Atlas 2001 monthly temperature and salinity data and the Argos drifting buoy trajectories.