Eddy-driven transports in the Antarctic Circumpolar Current

在南大洋，涡动驱动的输送可以与平均输送一样大。特别是纬向、横锋输送受中尺度涡动活动的影响甚至控制。另一方面，这些运输使南大洋成为全球碳循环中的主要海洋汇。在海洋模型中，必须充分解决这种变异性或将其参数化。Gent和McWilliams（1990）的参数化方法目前用于解释这种涡驱动输运，其中必须指定所谓的厚度扩散系数K。目前已知的只有大约I量级的«，但是，特别是在南大洋，K的选择强烈影响质量和示踪剂的纬向输送，因此对于量化南大洋在气候系统和全球碳循环中的作用至关重要。建议从现有的现实的涡旋分辨海洋模式的合成数据来估计南大洋的厚度扩散率K。虽然以前的尝试突出了旋转涡流通量的问题，使估计过程复杂化，但最近已经表明，物理上有意义的旋转通量的定义和使用减少了这个问题。因此，南大洋K的可靠估计首次出现。此外，建议估计海洋模型预测的平均数量和厚度扩散率之间的关系，为了建立一个自洽的涡流参数化。

In the Southern Ocean, eddy-driven transports can be as large as mean transports. In particular the meridional, cross frontal transports are affected or even controlled by meso-scale eddy activity. On the other hand, these transports set the role of the Southern Ocean as a major oceanic sink in the global carbon cycle. In ocean models, such variability has to be adequately resolved or parameterised. The parameterisation by Gent and McWilliams (1990) is currently used to account for such eddy-driven transports, in which the so-called thickness diffusivity K has to be specified. Only a rough order of I magnitude is currently known for «, but, in particular in the Southern Ocean, the choice of K strongly affects meridional transports of mass and tracers and is therefore of crucial importance to quantify the role of the Southern Ocean in the climate system and the global carbon cycle. It is proposed to estimate the thickness diffusivity K in the Southern Ocean from synthetic data of an existing realistic eddy-resolving ocean model. While previous attempts highlight the problem of rotational eddy fluxes which complicate the estimation procedure, it has been recently shown that the definition and use of physically meaningful rotational fluxes reduces this problem. Therefore, reliable estimates of K in the Southern Ocean appear possible for the first time. Furthermore, it is proposed to estimate relations between mean quantities predicted by ocean models and thickness diffusivity, necessary in order to build a self-consistent eddy parameterisation.