Lagrangian Geography of the Deep Gulf of Mexico
Lagrangian Geography of the Deep Gulf of Mexico
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墨西哥湾拉格朗日地理
DOI：
10.1175/jpo-d-18-0073.1
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发表时间：
2018
影响因子：
3.5
通讯作者：
J. Sheinbaum
中科院分区：
文献类型：
--
作者：
P. Miron;F. Beron;M. Olascoaga;G. Froyland;P. Pérez‐Brunius;J. Sheinbaum
利用墨西哥湾声学跟踪（RAFOS）浮标的轨迹，我们构建了墨西哥湾1500 - 2500米层的拉格朗日环流的地理结构。这是通过建立拉格朗日动力学的马尔可夫链表示来实现的。地理上由弱相互作用的省份组成，这些省份在深度上限制了连通性。主要地理包括两个地区几乎相等的省份，由大致的经向边界分开。在西（东）省的居住时间约为4.5（3.5）年。这些省份之间的交换是通过一个缓慢的气旋环流来实现的，这个环流在盆地西部受到f/H的约束，其中f是科里奥利参数，H是深度。次要省份形状各异，面积较小，居住时间约为0.4至1.2年左右。除主要省份外，深层拉格朗日地理与最近从卫星跟踪的漂流者轨迹推断的表层拉格朗日地理并不相似。这意味着不同的连通性特征对污染物（如石油）在地表和深处的扩散有潜在的影响。卫星跟踪剖面（Argo）浮标的马尔可夫链分析为我们的结果提供了支持，该浮标虽然形成了一个较小的数据集，并且与RAFOS浮标具有看似不同的水跟随特征，但却复制了拉格朗日地理的主要方面。我们的结果在化学示踪剂释放实验的独立结果中得到了进一步的验证。
Using trajectories from acoustically tracked (RAFOS) floats in the Gulf of Mexico, we construct a geography of its Lagrangian circulation within the 1500–2500-m layer. This is done by building a Markov-chain representation of the Lagrangian dynamics. The geography is composed of weakly interacting provinces that constrain the connectivity at depth. The main geography includes two provinces of near-equal areas separated by a roughly meridional boundary. The residence time is about 4.5 (3.5) years in the western (eastern) province. The exchange between these provinces is effected through a slow cyclonic circulation, which is well constrained in the western basin by preservation of f/H, where f is the Coriolis parameter and H is depth. Secondary provinces of varied shapes covering smaller areas are identified with residence times ranging from about 0.4 to 1.2 years or so. Except for the main provinces, the deep Lagrangian geography does not resemble the surface Lagrangian geography recently inferred from satellite-tracked drifter trajectories. This implies disparate connectivity characteristics with potential implications for pollutant (e.g., oil) dispersal at the surface and at depth. Support for our results is provided by a Markov-chain analysis of satellite-tracked profiling (Argo) floats, which, while forming a smaller dataset and having seemingly different water-following characteristics than the RAFOS floats, replicate the main aspects of the Lagrangian geography. Our results find further validation in independent results from a chemical tracer release experiment.