论文标题
拉格朗日对跨海面的子尺度电流的分散和运输研究
Lagrangian study of dispersion and transport by submesoscale currents at an upper-ocean front
论文作者
论文摘要
使用材料点（示踪剂颗粒）研究以局部流体速度进行的材料点（示踪剂颗粒）研究了三维传输途径，垂直传输的时间尺度以及在上界前沿的集体尺度电流的分散特性。占主导地位（0.1-10 km）动力学的连贯的子尺度涡流丝和涡流，在此处量化了至关重要的作用。这些相干结构是通过斜压不稳定性的非线性演化而产生和维持的。颗粒的集体运动有助于识别前部运输的共同特征。发现中央区域中的颗粒分为倾斜的裂片，每个叶都与涡流相关，并且与前传递边缘颗粒的重和浅色边缘相关的细丝与裂片。新颗粒进入叶的通量会导致局部颗粒进行调整，从而导致前部趋势。垂直的粒子运动显示了多个时间尺度 - 一个小时内O（10）m垂直位移的快速时间尺度，并且近惯性时间尺度较慢，与增长不稳定的内在时间尺度相当。快速时间尺度运动通常发生在涡流中。总体俯冲过程比细丝中垂直速度的巨大速度所期望的较慢，并且需要随着横向运动和垂直运动之间的持续相关性。通过跟踪颗粒的云，我们表明它们的质量下孔/Upwell的中心在1-2个惯性时间段内，此后进行调整以亚持续时间尺度。已经研究了使用单粒子统计量的子尺度湍流的分散特性。四个颗粒簇的形状变化揭示了变形为细的针状结构。
The three-dimensional transport pathways, the time scales of vertical transport, and the dispersion characteristics of submesoscale currents at an upper-ocean front are investigated using material points (tracer particles) that advect with the local fluid velocity. Coherent submesoscale vortex filaments and eddies which dominate submesoscale (0.1 - 10 km) dynamics are found to play a crucial role which is quantified here. These coherent structures are generated and sustained through nonlinear evolution of baroclinic instability. The collective motion of particles helps identify common features of transport at the front. It is found that the particles in the central region organize into inclined lobes, each associated with an eddy, and the filaments associated with the heavy- and light-edges of the front transfer edge particles to the lobes. This flux of new particles into the lobe causes local particles to adjust, which leads to slumping of the front. The particle motion in the vertical shows multiple time scales -- a fast time scale with O(10) m vertical displacement within an hour and a slower near-inertial time scale, comparable to the intrinsic time scale of the growing instability. The fast time scale motions typically occur in the vortex filaments. The overall slumping process is slower than what one might anticipate from the large magnitude of vertical velocity in the filaments and requires a sustained correlation over time between the lateral and the vertical motion. By tracking clouds of particles, we show that their centers of mass downwell/upwell over 1-2 inertial time periods, after which an adjustment follows with a sub-inertial time scale. The dispersion characteristics of the submesoscale turbulent currents using single- and pair-particle statistics have been investigated. The shape change in clusters of four particles reveals deformation into thin, needle-like structures.
