基于潜标观测的牛郎海山的深海海流的低频变化特征

Low frequency variation of deep current at Niulang Seamount based on submarine mooring observation

本文利用在西太平洋牛郎海山布放的两套锚系潜标获取的长时间海流观测数据,分析了深海的海洋动力环境特征,着重阐释了该海域海流的全水深垂向结构及其低频变化特征。结果表明:(1)年平均海流及其变化幅度均在上层最大、中层和深层次之、中深层最小;(2)年平均上,150 m以浅的海流为东向的副热带逆流,150 m以深和中层为西向流;山顶处的近底层海流为较稳定的弱南向流,山底处的近底层海流为西南向流;(3)在山顶和山底,各深度层次的海流在全年均表现出100 d左右的振荡周期;在2000 m以浅,各深度层次的海流振荡的位相基本一致,振荡幅度在表层最强、随深度的增加而减小;在2000 m以深,海流变化的位相与2000 m以浅相反,振荡幅度在4000 m最强。

Based on the long-term observation obtained from two sets of submarine mooring system deployed at Niulang Seamount in the western Pacific,the vertical distribution of the deep currents and the temporal variation characteristics were analyzed in the paper.The results show that:(1)The annual mean ocean currents and the variations were the largest in the upper layer,the second in the middle and deep layers,and the smallest in the middle-deep layers.(2)The subtropical countercurrent was at the depth shallower than 150 m,and the northward current was at depth deeper than 150 m and at the middle layers;the near bottom current was weak southward at the summit of the seamount,but southwestward at the bottom of the seamount.(3)Both at the summit and bottom of the seamount,the currents showed a seasonal oscillation with the most energetic oscillation at a period of about 100 d throughout the water column;at depth above 2000 m,currents showed a synchronous oscillation in the throughout the water column,with the oscillation amplitude decreasing with depth;current oscillation at deep layers(below 2000 m)were in opposite phase with that at the upper layers,and the oscillation amplitude was the strongest at 4000 m.