1366 / 2024-09-25 15:53:25

Strong Eddy Kinetic Energy Anomaly Induced by Baroclinic Instability in the Southwest Region of the Kerguelen Plateau, East Antarctica

eddy kinetic energy,Circumpolar Deep Water,Baroclinic Instability,polar dynamics

Session 35 - Eddy variability in the ocean and atmosphere: dynamics, parameterization and prediction

Eddy activity is particularly prominent in the Southern Ocean due to the instabilities of the dynamic Antarctic Circumpolar Current (ACC), which plays a critical role in energy transport of the global ocean. The Indian sector of the Southern Ocean is a typical eddy-rich region with strong Eddy Kinetic Energy (EKE) and associated energy conversions among different energy reservoirs (kinetic energy and potential energy of the eddy and mean flow). In this study, a systematic energetics analysis framework is employed to investigate the notable anomalies of an intensified EKE event observed in the southwest region of the Kerguelen Plateau in 2017, utilizing a reanalysis product. The EKE anomalies, presenting across all depths, emerged in April, peaked during the austral winter, and persisted into the subsequent summer. Energetics analysis indicates that the pronounced EKE anomalies are primarily determined by baroclinic instability, with distinct governing mechanisms at the surface and in the internal ocean. The anomalous intrusion of warm Circumpolar Deep Water intensified the baroclinic energy conversion in the subsurface, contributing significantly to the EKE anomalies. Moreover, strong anomalous wind-induced Ekman pumping served to amplify the lifting of isopycnals, which enhanced the baroclinic instability and subsequently intensified the EKE anomalies. This study sheds new light on underlying mechanisms governing local polar dynamics and provides insights into the intricate interaction between ocean dynamics and energy distribution in the Antarctic region.