Direct measurements of World Ocean tidal currents with surface drifters
Direct measurements of World Ocean tidal currents with surface drifters
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DOI：
10.1002/2015jc010818
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发表时间：
2015-10-01
影响因子：
3.6
通讯作者：
Centurioni, Luca
中科院分区：
文献类型：
--
作者：
Poulain, Pierre-Marie;Centurioni, Luca
分析表面漂流物的速度以研究整个世界海洋的潮流。1979-2013年期间的全球漂流数据集用于描述全球尺度表层潮流的地理结构，分辨率为2度。谐波分析进行了两个半日，两个昼夜，和四个推断的潮汐成分。通过直接观测，绘制了世界大洋的潮流特征图（半长轴振幅、旋转系数、潮汐椭圆倾角和格林威治相位）。M2流在所有浅海陆架上占主导地位，其量级超过60 cm/s。在大西洋中脊、西南印度洋脊和马里亚纳海脊等主要深海地形特征上，也有大量（4-5厘米/秒）。S2电流的振幅通常是M2电流的一半，最大值约为30 cm/s。K1和O 1海流在许多浅海中很重要。它们在接近30度N/S的转向纬度附近很大，在那里它们与相同频率的惯性运动合并。它们在南中国海和菲律宾海也很大。旋转系数图表明，在北方（南）半球，所有潮汐运动基本上都是顺时针（逆时针）的。将潮流旋转系数与自由斜压重力惯性波理论进行了比较。M2分潮的格林威治位相具有大尺度相干传播模式，可以解释为正压潮的传播。
Velocities of surface drifters are analyzed to study tidal currents throughout the World Ocean. The global drifter data set spanning the period 1979-2013 is used to describe the geographical structure of the surface tidal currents at global scale with a resolution of 2 degrees. Harmonic analysis is performed with two semidiurnal, two diurnal, and four inferred tidal constituents. Tidal current characteristics (amplitude of semimajor axis, rotary coefficient, tidal ellipse inclination, and Greenwich phase) are mapped over the World Ocean from direct observations. The M2 currents dominate on all the shallow continental shelves with magnitude exceeding 60 cm/s. They are also substantial (4-5 cm/s) over the main deep topographic features such as the Mid-Atlantic Ridge, the Southwest Indian Ridge, and the Mariana Ridge. The S2 currents have amplitudes typically half the size of the M2 currents, with a maximum of about 30 cm/s. The K1 and O1 currents are important in many shallow seas. They are large in the vicinity of the turning latitudes near 30 degrees N/S where they merge with inertial motions of the same frequency. They are also substantial in the South China Sea and Philippine Sea. Maps of rotary coefficients indicate that all tidal motions are essentially clockwise (anticlockwise) in the Northern (Southern) Hemisphere. The rotary coefficient of the tidal currents is compared with the theory of freely and meridionally propagating baroclinic inertia-gravity waves. The Greenwich phase of the M2 constituent has large-scale coherent propagation patterns which could be interpreted as the propagation of the barotropic tide.