北部湾春季季风转换时期两潜标站余流分析

Analysis of residual current during spring monsoon transition in the Beibu Gulf

2007年春季季风转换期间,在北部湾湾口两站利用潜标观测获得了80余天的流速剖面等资料序列。结合NASA喷气推进实验室物理海洋学数据分发存档中心提供的QuikSCAT海表面风场数据,以及NOAA国家气候数据中心提供的海表面温度数据,利用交叉谱分析方法对观测期间两站余流结构及其影响因子进行分析。结果表明:1)春季季风转换时期,北部湾风场北分量具有周期为10d左右的震荡。风的输运造成密度场结构出现相应的震荡,从而会引起密度流的变化。2)M4站余流主要由风场控制,水体向北部湾内输运。3)M5站表底层余流差距较大,整层余流均受到了风的直接影响,而表层还受到了由风引起的密度流变化的影响,因此风通过两种方式影响了M5站的余流。

Current profile data of about 80 days were obtained by the submersible buoy measurement at two stations at the mouth of the Beibu Gulf during the spring monsoon transition in 2007. Using cross spectrum analysis, the structure of residual currents and the factors that influence the structure are analyzed, with the addition of QuikSCAT sea-surface wind data ob- tained from NASA Jet Propulsion Laboratory Physical Oceanography Distributed Active Archive Center, and sea-surface temperature data provided by NOAA National Climatic Data Center. The results are as follows. The northward component of the wind had oscillations with a period about 10 days during spring monsoon transition in the Beibu Gulf. The wind could generate the oscillation of the density field, which could lead to the variation of density current. The residual currents at Sta- tion M4 were mainly controlled by wind. Water at Station M4 was transported into the Beibu Gulf. The residual currents at Station M5 were very different between surface and bottom. The whole water column was affected directly by wind, while the surface layer was also affected by the variation of density current controlled by wind. So wind affected residual currents in two ways at Station M5.