308 / 2024-09-13 20:19:01

Dynamics of Interannual Eddy Kinetic Energy Modulations in a Western Boundary Current

Western Boundary Current,Eddy Kinetic Energy

Among Western Boundary Currents, the East Australian Current (EAC) has a more energetic eddy field relative to its mean flow, however, the relationship between upstream transport and downstream eddy kinetic energy (EKE) is still unclear. We investigate the modulation of downstream EKE in the EAC's typical separation region (Tasman EKE Box) (33.1°S–36.0°S) based on a long-term (22-year), high-resolution (2.5–6 km) model simulation and satellite altimeter observations from 1994 to 2016. Our results show that the poleward EAC transport at 28°S leads the EKE in the Tasman EKE Box by 93–118 days. Barotropic instabilities are the primary source of EKE, and they control EKE variability in the EAC system. Anticyclonic eddies shed from the EAC dominate from 33°S~36°S during high-EKE periods, but in low-EKE periods anticyclonic eddies penetrate even further south by ~2°S.