Scientists have developed a new diagnostic framework to better understand and analyze the intricate isoneutral oceanic mesoscale eddy transport in the vast Southern Ocean. Mesoscale eddies, which contain most of the ocean kinetic energy, impact ocean material transport, momentum budget, and interactions with large-scale and submesoscale ocean circulation. Therefore, understanding their behavior and resolving or at least parameterizing the process in a numerical model is necessary.

The research, published in the Journal of Advances in Modeling Earth Systems recently, offers a more nuanced perspective on eddy potential vorticity (PV) transport dynamics. "In this new framework, we introduce Leonard's decomposition in Large Eddy Simulations and the stationary-transient decomposition to create a more holistic picture of the transport by ocean eddies", explained the first author Mr. XIE Jingwei, the PhD candidate with the Institute of Atmospheric Physics at the Chinese Academy of Sciences.

Originally proposed for atmospheric flows in the 1960s, Large-eddy simulation (LES) has become a highly promising and successful method for simulating turbulent flows, especially when integrated with large-scale ocean modeling. This research also introduces several LES concepts, hoping to enlighten any potential ocean modeling and parameterization.

The researchers applied their diagnostic method to realistic model data of the Southern Ocean and investigated the eddy transport regarding scale dependence, potential enstrophy, and anisotropy. "By systematically investigating the multiscale dynamic properties in the generalized eddy PV flux and its corresponding PV transport tensor, this research could provide theoretical support for any potential parameterization." said XIE.

While the diagnostic framework may seem highly technical, its appropriate application helps fill knowledge gaps between ocean dynamics and ocean modeling, according to XIE.

Citation: Xie, J., Liu, H., & Lin, P. (2023). A multifaceted isoneutral eddy transport diagnostic framework and its application in the Southern Ocean. Journal of Advances in Modeling Earth Systems, 15, e2023MS003728. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023MS003728

Link：https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2023MS003728

Contact：LIU Hailong, lhl@lasg.iap.ac.cn