Modulation of Eddy Kinetic Energy by Seasonal Extension of the Eastern Weddell Gyre

Abstract Active eddies in the eastern Weddell Gyre (WG) facilitate water mass exchange between the WG and warmer Antarctic Circumpolar Current, driving warm inflow into the WG. Using observations and data‐assimilating model output, the impact of seasonal extension of the eastern WG on the local eddy kinetic energy (EKE) field was investigated. By altering the ambient density field, the gyre seasonal extension modulates both EKE production via baroclinic instability (BCC) and EKE redistribution through the pressure work (PW). When WG extends eastward in autumn‐winter, the more enhanced PW drives EKE outward flux outweighing its local production by BCC. In contrast, during spring‐summer as WG contracts, the dominant role of BCC production over PW removal favors EKE accumulation. Understanding these dynamics is critical to predicting eddy‐induced warm inflow into a potentially expanding WG under climate change, and also provides insight into interactions between eddy and mean flow fields in the Southern Ocean.