Title: Dynamic Mechanism of Seasonal Variability of Eddy Kinetic Energy in the Equatorial Pacific Ocean

Journal: Journal of Geophysical Research, 122:3240-3252

Authors: WANG M. -Y., Y. Du*, B. Qiu, X. -H. Chen, Y. -Y. Luo, X. Chen, and M. Feng

Abstract: Enhanced mesoscale eddy activities or tropical instability waves (TIWs) exist along the northern front of the cold tongue in the eastern equatorial Pacific Ocean. In this study, we investigate seasonal variability of eddy kinetic energy (EKE) over this region and its associated dynamic mechanism using a global, eddy‐resolving ocean general circulation model (OGCM) simulation, the equatorial mooring data, and satellite altimeter observations. The seasonal‐varying enhanced EKE signals are found to expand westward from 100°W in June to 180°W in December between 0°N and 6°N. This westward expansion in EKE is closely connected to the barotropically‐baroclinically unstable zonal flows that are in thermal‐wind balance with the seasonal‐varying thermocline trough along 4°N. By adopting an 1½‐layer reduced‐gravity model, we confirm that the seasonal perturbation of the thermocline trough is dominated by the anticyclonic wind stress curl forcing, which develops due to southerly winds along 4°N from June to December.