Mean surface circulation and mesoscale turbulent flow characteristics in the eastern South Pacific from satellite tracked drifters
Mean surface circulation and mesoscale turbulent flow characteristics in the eastern South Pacific from satellite tracked drifters
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DOI：
10.1029/2004jc002628
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发表时间：
2005-05-21
影响因子：
3.6
通讯作者：
Pizarro, O
中科院分区：
文献类型：
--
作者：
Chaigneau, A;Pizarro, O
[1] 利用 1979 年至 2003 年的漂流浮标轨迹研究了南太平洋东部地区（南纬 10 度 - 34 度，西经 70 度 - 100 度）的环流。突出了三种不同的流态：南赤道流，在南纬 26 度以北向西流动，表面速度为 7 - 8 cm s(-1)；南太平洋洋流，类似于南纬 25 度 - 30 度以南 2 厘米 s(-1) 的东向洋流；智利-秘鲁洋流在西经82度以东、南纬22度以南发现了一股类似6 cm s(-1)的西北向气流。速度方差分布表明区域气流本质上是各向异性的。从漂流器测量和卫星测高数据获得的涡流动能图显示出类似的模式，南美海岸附近的能量水平较高。湍流的拉格朗日时间和长度尺度显示，纬向方向的典型值为 5.9 +/- 0.6 天和 40.7 +/- 5.4 公里，经向方向为 3.5 +/- 0.4 天和 29 +/- 3.4 公里。向东和向北方向的估计扩散系数分别为(4.9+/-0.5)×10(7)cm(2)s(-1)和(2.6+/-0.3)×10(7)cm(2)s(-1)。最后，我们估计了水平平流和横向扩散对混合层热量和盐收支的各自作用。在海岸附近，表层的横向湍流通量比与大规模环流相关的水平输送大两倍；平均水平热和盐扩散通量约为25 W m(-2) 和50 g m(-2) d(-1)。
[1] Circulation of the eastern South Pacific region (10 degrees - 34 degrees S, 70 degrees - 100 degrees W) was studied using drifting buoy trajectories from 1979 to 2003. Three different current regimes were highlighted: the South Equatorial Current, flowing westward north of 26 degrees S with surface velocities of 7 - 8 cm s(-1); the South Pacific Current, an eastward current of similar to 2 cm s(-1) south of 25 degrees - 30 degrees S; and the Chile-Peru Current, a northwestward flow of similar to 6 cm s(-1) found to the east of 82 degrees W and south of 22 degrees S. The velocity variance distribution showed the regional flow to be anisotropic in nature. Maps of eddy kinetic energy obtained from drifter measurements and satellite altimetry data showed similar patterns, with higher energy levels near the South American coast. The Lagrangian time and length scales of the turbulent flow revealed typical values of 5.9 +/- 0.6 days and 40.7 +/- 5.4 km in the zonal direction and of 3.5 +/- 0.4 days and 29 +/- 3.4 km in the meridional direction. The estimated diffusivities were (4.9 +/- 0.5) x 10(7) cm(2) s(-1) and (2.6 +/- 0.3) x 10(7) cm(2) s(-1) in the eastward and northward directions, respectively. Finally, we estimated the respective role of horizontal advection and lateral diffusion on the mixed layer heat and salt budgets. Near the coast the lateral turbulent fluxes in the surface layer were two times larger than the horizontal transports associated with the large-scale circulation; mean horizontal heat and salt diffusive fluxes were around 25 W m(-2) and 50 g m(-2) d(-1).