Intermediate-depth Eddies East of Mindanao: Causes and Consequences

最近的观测显示，在菲律宾以东的太平洋低纬度西部边界地区，温跃层下方有令人惊讶的强涡流。最大速度超过0.5 m s-1，涡流至少延伸至2000 m深度。然而，迄今为止对涡旋的观测是不精确的，获得详细的测量，具有良好的时间和空间覆盖，是昂贵的。幸运的是，最近具有0.1度水平网格的数值海洋环流模式与现有观测结果非常吻合，表明对这些模式的输出进行详细分析，结合现有测量和新的数值过程研究，将是实现项目目标的一种经济有效的方法。在这项研究中，夏威夷大学的研究人员将利用现有的观测结果和高分辨率模型输出，更新和完善他们对棉兰老岛外洋流的变化和垂直结构的描述。通过使用能量收支、剪切模式分析和一系列数值过程研究，研究小组将确定在中深度产生能量流的过程。他们还将用数值输出模型进行拉格朗日示踪实验，以检验涡流对水性质分布的影响。最后，科学家们将通过对涡度和能量平衡的分析来描述涡旋在大尺度环流动力学中的作用。从这项工作中收集的结果将解决主要的物理海洋学问题，例如：是什么决定了中尺度能量场的特征，它在空间和时间上是如何变化的，以及更大规模的后果是什么？虽然这些问题没有全球性的答案，但必须通过对特定地区特定过程的详细研究，然后对可能活跃类似过程的其他地区进行预测，来部分地积累一个总体的认识。除了这项工作的智力价值外，这项研究还将加强与日本海洋科学技术中心（JAMSTEC）和日本地球模拟器中心的国际合作。它还将支持和培训一名博士候选人。

Recent observations have shown surprisingly strong eddies below the thermocline in the Pacific low-latitude western boundary region east of the Philippines. Maximum velocities have exceeded 0.5 m s-1, and the eddies extend to at least 2000 m in depth. However, observations of eddies to date are imprecise, and obtaining detailed measurements, with good temporal and spatial coverage, is expensive. Fortunately, recent numerical ocean general circulation models with a 0.1-degree horizontal grid agree well enough with existing observations to indicate that a detailed analysis of the output from these models, in conjunction with existing measurements and new numerical process studies, will be a cost-effective method for achieving the project objectives.In this study, researchers at the University of Hawaii will update and refine their description of the variability and vertical structure of the currents off Mindanao using available observations and high-resolution model output. By using energy budgets, shear mode analysis, and a series of numerical process studies the team of researchers will determine the processes generating energetic flows at intermediate depths. They will also conduct Lagrangian tracer experiments with the numerical output models to examine the consequences of the eddies for water property distributions. Finally, the scientists will describe the eddies' role in the dynamics of the larger-scale circulation via analysis of vorticity and energy balances. The results gathered from this work will address major physical oceanographic questions, such as: what determines the characteristics of the mesoscale energy field, how does it vary in space and time, and what are the larger-scale consequences? Though the questions do not have global answers, a general understanding must be accumulated in part by detailed studies of specific processes in specific regions, followed by predictions of other regions in which similar processes are likely to be active. In addition to the intellectual merit of the work, this research will strengthen international collaborations with the Japanese at the Marine Science and Technology Center (JAMSTEC) and the Earth Simulator Center in Japan. It will also support and train a PhD candidate.