Mixing Inferred from Coherent Mesoscale Eddies (MICME)

该项目将为利用卫星测高跟踪相干中尺度涡旋估算地表中尺度扩散系数提供一种新技术。估计的扩散系数将有助于限制海洋示踪剂的分布，并可用于验证和改进数值模式中的中尺度涡参数化。这项技术的发展也将提供对海洋宏观湍流动力学和中尺度涡旋混合机制的见解，这将有助于理解各种流动状态下的涡旋输送。现代气候模式的海洋分量分辨率不足以解决中尺度涡旋；因此，涡流示踪剂传输通常被参数化为扩散过程。然而，这些模式中示踪剂扩散率的幅度和空间格局的变化可能导致其模拟气候的巨大差异。这个项目将量化连贯的海洋涡流对中尺度混合的影响。中心假设是，相干中尺度涡旋的弥散将提供对海洋中尺度扩散率的有效估计。第一个目标是确定在理想环流模式中，不均匀性如何影响相干中尺度涡旋运动与示踪剂扩散率之间的关系。然后，该项目将利用卫星测高的相干中尺度涡旋轨迹估计全球中尺度涡旋扩散系数的大小和各向异性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will provide a new technique for estimating surface-layer mesoscale diffusivity by tracking coherent mesoscale eddies using satellite altimetry. The estimated diffusivities will help constrain the distribution of oceanic tracers and can be used to validate and improve mesoscale eddy parameterizations in numerical models. Development of this technique will also provide insights into dynamics of ocean macro-turbulence and the mechanisms of mesoscale eddy mixing, which could contribute to the understanding of eddy transport in a broad variety of flow regimes.The ocean components of modern climate models are of insufficient resolution to resolve mesoscale eddies; thus, eddy tracer transport is typically parameterized as a diffusive process. However, variations in the magnitude and spatial pattern of tracer diffusivity in these models can potentially lead to large differences in their simulated climates. This project will quantify the impact of coherent ocean eddies on mesoscale mixing. The central hypothesis is that the dispersion of coherent mesoscale eddies will provide an efficient estimate of the mesoscale diffusivity in the ocean. The first objective is to identify how inhomogeneity affects the relationship between the movements of coherent mesoscale eddies and tracer diffusivities in an idealized general circulation model. The project will then estimate the magnitude and anisotropy of global mesoscale eddy diffusivity with coherent mesoscale eddy trajectories from satellite altimetry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.