基于Argo历史观测的南海海盆尺度中层流场研究

针对南海海域海流环境复杂、中层实测数据量少的现状，本文基于2006-2016年布放在南海海域的114个Argo剖面浮标的卫星定位等信息，采用基于背景流和惯性流外推的最小二乘方法，获取南海海域1 200 m深中层流场信息，并采用Divand变分插值的方法形成网格化季节流场。结果表明:（1）针对南海中层（1 200 m）流场，单个Argo浮标可以刻画出具体的中尺度结构，如越南沿岸的反气旋涡，半径约为120 km，最大流速约为9.6 cm/s，平均流速为5.3 cm/s；（2） Argo网格化流场表明海盆尺度中层流场南海南部为反气旋环流结构，北部为气旋式环流，同时在吕宋海峡口存在从南海至太平洋的水体交换；（3）将该流场信息与HYCOM和YoMaHa'07两种资料对比，吻合度较高，与HYCOM再分析资料的偏差分布趋近于正态分布，海流的东西向分量的均方根误差为3.28 cm/s，南北向分量的均方根误差为3.26 cm/s。总体而言，利用Argo轨迹资料能够有效地反演出南海地区海盆尺度的中层环流特征。

Research on mid-depth current of basin scale in the South China Sea based on historical Argo observations

According to the state of art of South China Sea (SCS) which is with complex currents environment and a small number of mid-depth observations, a gridding seasonal velocity field is generated via Divand variational interpolation method using mid-depth velocity data of 1200 m derived from the satellite positioning of 114 Argo profiling floats deployed in SCS from 2006 to 2016 using the method of least square and based on the background and inertial currents. The conclusions could be drawn as follows. (1) Velocity trajectory of one single Argo profiling float could describe the concrete structure of the mesoscale phenomenon, e.g. the anti-cyclonic mesoscale eddy at the mid-depth (1 200 m) off the Vietnam east coast which has a radius of 120 km, a maximum current velocity of 9.6 cm/s and a average current velocity of 5.3 cm/s. (2) The gridding seasonal currents field generated from Argo demonstrates that the mid-depth current of basin scale has the anti-cyclonic structure in southern part of SCS and cyclonic structure in northern part. Meanwhile, there exists water exchange from SCS to the Pacific Ocean through Luzon Strait. (3) The generated gridding seasonal currents field is highly consistent with HYCOM Reanalysis and YoMaHa''07 data. Comparing the generated currents field with HYCOM Reanalysis data, the distribution of the departure of the two is normal, while the root mean square error of zonal component of the velocity of the currents is 3.28 cm/s and the counterpart of the meridional component is 3.26 cm/s. All in all, the features of the basin scale mid-depth circulation in SCS could be efficiently retrieved by the Argo trajectory data.