标题： 高频和平衡运动对海洋表面拉格朗日粒子对弥散的影响 显示英文标题

标题： Effects of high-frequency and balanced motions on Lagrangian pair dispersion at the ocean surface

摘要： 我们研究了全球海洋模拟中拉格朗日粒子相对分散的性质，该模拟同时解析了惯性重力波（IGW）和中尺度及次中尺度（M/SM）湍流。 更具体地说，我们测试了离散规律是否依赖于欧拉动能谱的形状，这是准地转湍流理论所预测的。 为此，我们关注两个区域，分别是黑潮延伸区和墨西哥湾流，在夏季和冬季，相对于M/SM，IGW的重要性有所不同。 在冬季，拉格朗日统计指标总体上与动能谱的形状一致。 相反，在夏季，当次中尺度能量较低且高频内波变得重要时，预期的分散属性与谱之间的关系似乎不成立。 这种明显的差异可以通过将流动分解为几乎平衡的运动和内部重力波来解释，并表明后者在小尺度上主导了动能谱。 我们的结果与高频IGW不影响相对分散的假设一致，这表明较大尺度上的几乎平衡的主要旋转流动成分控制着相对分散。 这些结果强调了从宽幅高度计（如SWOT）推导的地转速度可能存在局限性，而当前的卫星测量任务可能提供互补信息以估算表面分散。 显示英文摘要

摘要： We investigate the properties of relative dispersion of Lagrangian particles in a global-ocean simulation resolving both inertia-gravity waves (IGW) and meso and submesoscale (M/SM) turbulence. More specifically, we test if the dispersion laws depend on the shape of the Eulerian kinetic energy spectrum, as predicted from quasi-geostrophic turbulence theory. To this end, we focus on two areas, in the Kuroshio Extension and in the Gulf Stream, for which the relative importance of IGW compared to M/SM vary in summer and winter. In winter, Lagrangian statistical indicators return a picture in overall agreement with the shape of the kinetic energy spectrum. Conversely, in summer, when submesoscales are less energetic and higher-frequency internal waves gain importance, the expected relations between dispersion properties and spectra do not seem to hold. This apparent discrepancy is explained by decomposing the flow into nearly-balanced motions and internal gravity waves, and showing that the latter dominate the kinetic energy spectrum at small scales. Our results are consistent with the hypothesis that high-frequency IGWs do not impact relative dispersion, which is then controlled by the nearly-balanced, mainly rotational, flow component at larger scales. These results highlight that geostrophic velocities derived from wide-swath altimeters, such as SWOT, may present limits when estimating surface dispersion, and that current measuring satellite missions may provide the complementary information to do so.