Surface Semi-Geostrophic Dynamics: mixing from local to nonlocal dynamics

观测和数值研究表明，海洋在小于中尺度的尺度上表现出明显的动力学特征。了解这些动力学的特性及其在湍流传输和混合热量、营养物和污染物等特性方面的作用，对于气候模式中混合的正确参数化十分重要。在这个项目中，我们的目标是研究在海洋中的横向混合的亚中尺度动力学，特别是由非地转涡旋产生的边界，使用半地转近似。为了研究被动示踪剂的搅拌和混合，将进行地面半地转湍流的数值试验。在不同的Rossby数下进行不同的实验，以研究锋面动力学对示踪剂扩散的影响。结果将与其他经典的湍流模式，如表面准地转近似进行比较。

Observational and numerical works show that the ocean displays a significant presence of dynamics at scales smaller than the mesoscale. Understanding the properties of these dynamics and their role in the turbulent transfer and mixing of properties such as heat, nutrients and pollutants is important for the correct parameterization of mixing in climate models. In this project we aim to study the lateral mixing in the ocean by submesoscale dynamics, in particular by ageostrophic eddies produced at boundaries, using the semi-geostrophic approximation. Numerical experiments of surface semi-geostrophic turbulence will be performed in order to study the stirring and mixing of passive tracers. Different experiments at different Rossby numbers will be performed to study the effects of the frontal dynamics on the dispersion of the tracer. Results will be compared with other classic turbulence models, such as the surface quasi-geostrophic approximation.