Horizontal dispersion of ocean tracers in internal wave shear
Horizontal dispersion of ocean tracers in internal wave shear
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DOI：
10.1029/2011jc007213
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发表时间：
2011-11
影响因子：
--
通讯作者：
J. Steinbuck;J. Koseff;A. Genin;M. Stacey;S. Monismith
中科院分区：
文献类型：
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作者：
J. Steinbuck;J. Koseff;A. Genin;M. Stacey;S. Monismith
[1] 使用拉格朗日粒子跟踪模型检查由于垂直扩散和内波垂直剪切相互作用而导致的海洋示踪剂的水平扩散。对于无界垂直范围的理想化正弦水平速度分布，当速度变化上的粒子扩散的时间尺度和剪切振荡的周期相当时，粒子云的不可逆水平分散是最大的。对于亚喀巴湾（红海）温跃层测得的速度剖面，粒子云的总色散和不可逆色散都倾向于随着垂直扩散、云高和云龄的增加而增加。总水平云方差和不可逆水平云方差通常随时间 (t) 增长，分别为 t0 到 t3 和 t1 到 t3。基于垂直恒定振荡剪切的现有分析模型对不可逆水平分散性的估计与粒子跟踪模型的估计非常一致，差异取决于垂直扩散和剪切的垂直变化，而这些变化并未纳入分析模型中。
[1] The horizontal dispersion of ocean tracers due to the interaction of vertical diffusion and the vertical shear from internal waves is examined using a Lagrangian particle-tracking model. For idealized, sinusoidal horizontal velocity profiles of unbounded vertical extent, the irreversible horizontal dispersion of particle clouds is maximal when the timescale of particle diffusion across the velocity variations and the period of shear oscillation are comparable. For measured velocity profiles from the thermocline in the Gulf of Aqaba (Red Sea), the total dispersion and irreversible dispersion of particle clouds both tend to increase with vertical diffusion, cloud height, and cloud age. The total and irreversible horizontal cloud variances typically grow with time (t) like t0 to t3 and t1 to t3, respectively. Estimates of the irreversible horizontal dispersivity from an existing analytical model based on vertically constant, oscillating shear agree remarkably well with estimates from the particle-tracking model, with differences dependent on the vertical variability in vertical diffusion and shear that are not incorporated in the analytical model.