根据漂流者资料计算的亚得里亚海拉格朗日量turbulence：不均匀性和非平稳性的影响
Lagrangian turbulence in the Adriatic Sea as computed from drifter data: effects of inhomogeneity and nonstationarity
摘要：
利用1990-1999年的漂流物资料，研究了亚得里亚海中尺度拉格朗日湍流的性质，着重讨论了非均匀性和非定常性的作用。初步研究了湍流速度统计对箱平均的依赖性，并选择了0.25的优先箱尺度。使用优化样条技术获得的独立估计比较证实了这一选择。三个主要区域被确定的速度统计是近似均匀的：两个边界电流，西（东）亚得里亚海电流，WAC（EAC），和南部中央环流，CG。CG区域的特征在于对称的概率密度函数的速度，近似指数自相关和定义良好的积分量，如扩散率和时间尺度。相反，边界区域是显着不对称的偏度表示优先事件的平均流的方向。沿平均流方向的自相关性具有两个时间尺度的特征，在EAC区域具有11-12天的缓慢衰减时间的次级指数。季节划分的数据表明，这种二级尺度是特别突出的夏秋季节。可能的物理解释的次级尺度进行了讨论，在低频波动的强迫和平均流曲率诱导波动的粒子轨迹。在亚得里亚海的运输模型的结果的后果进行了讨论。
英文摘要：
The properties of mesoscale Lagrangian turbulence in the Adriatic Sea are studied from a drifter data set spanning 1990-1999, focusing on the role of inhomogeneity and nonstationarity. A preliminary study is performed on the dependence of the turbulent velocity statistics on bin averaging, and a preferential bin scale of 0.25 is chosen. Comparison with independent estimates obtained using an optimized spline technique confirms this choice. Three main regions are identified where the velocity statistics are approximately homogeneous: the two boundary currents, West (East) Adriatic Current, WAC (EAC), and the southern central gyre, CG. The CG region is found to be characterized by symmetric probability density function of velocity, approximately exponential autocorrelations and well defined integral quantities such as di usivity and time scale. The boundary regions, instead, are significantly asymmetric with skewness indicating preferential events in the direction of the mean flow. The autocorrelation in the along mean flow direction is characterized by two time scales, with a secondary exponential with slow decay time of 11-12 days particularly evident in the EAC region. Seasonal partitioning of the data shows that this secondary scale is especially prominent in the summer-fall season. Possible physical explanations for the secondary scale are discussed in terms of low frequency fluctuations of forcings and in terms of mean flow curvature inducing fluctuations in the particle trajectories. Consequences of the results for transport modelling in the Adriatic Sea are discussed.
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