Surface dispersion properties give an immediate characterization of the spreading of passive and active tracers in the ocean, like pollutant and marine species. The Mediterranean sub-basins (Tyrrhenian, Adriatic, Ionian, Levantine and Aegean) are known as complex dynamic regions due to the presence of coherent structures on different motion scales. This paper focus on dispersion of the surface Mediterranean flow using the surface current data derived from two different drifter designs: the Coastal Ocean Dynamics Experiment (CODE) and the Surface Velocity Program (SVP) drifters. The absolute dispersion for small time scales (<2 days) shows similar anisotropic quasi-ballistic regimes in the five sub-basins. For intermediate time scales (2–15 days), the absolute dispersion shows the occurrence of an elliptic regime in all the Mediterranean sub-basins except in the Adriatic Sea, where the dominance of a hyperbolic regime is observed. The relative dispersion statistics show the presence of a non-local exponential regime in the Tyrrhenian sub-basin, with spatial scale smaller than the internal Rossby Radius of deformation DI. For spatial scales close to DI, two local relative dispersion regimes are found due to the influence of sub-basin scale structures: a Richardson regime in the Tyrrhenian and Aegean sub-basins and a shear/ballistic regime in other sub-basins. Furthermore, for large time scale (>15 days) and spatial scale larger than DI, our results emphasize a similarity in all the sub-basins with the presence of a quasi Random-walk regime and a quasi diffusive regime for the absolute and relative dispersion, respectively.

中文翻译：

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地中海亚盆地地表扩散分析

表面扩散特性可以直接表征海洋中被动和主动示踪剂的扩散，如污染物和海洋物种。地中海子盆地（第勒尼安、亚得里亚海、爱奥尼亚海、黎凡特和爱琴海）由于存在不同运动尺度上的连贯结构而被称为复杂的动态区域。本文使用源自两种不同漂流器设计的地表水流数据，重点研究地表地中海流的扩散：沿海海洋动力学实验 (CODE) 和表面速度程序 (SVP) 漂流器。小时间尺度（<2 天）的绝对离散度在五个子盆地中显示出类似的各向异性准弹道状态。对于中间时间尺度（2-15 天），绝对离散度表明，除亚得里亚海外，所有地中海子盆地都出现椭圆形状态，在那里观察到双曲线状态的优势。相对弥散统计表明，第勒尼安次盆地存在非局部指数制度，空间尺度小于变形 DI 的内部罗斯比半径。对于接近 DI 的空间尺度，由于子盆地尺度结构的影响，发现了两种局部相对分散机制：第勒尼安和爱琴海子盆地的理查森机制和其他子盆地的剪切/弹道机制。此外，对于大时间尺度（>15 天）和大于 DI 的空间尺度，