Controlling Influence of Ocean Mesoscale Eddy – Atmosphere Feedback on the Kuroshio Extension Jet

High-resolution satellite observations and numerical modeling have revealed strong mesoscale air-sea coupling in oceanic frontal regions replenished with energetic eddies. Using high-resolution eddy-resolving global and regional coupled climate models, we show that ocean mesoscale eddy-atmosphere (OME-A) feedback has a controlling influence on the Kuroshio Extension Jet (KEJ). Removing OME-A feedback results in a weaker and broader KEJ with a weaker cross-front temperature gradient in the Kuroshio Extension region. The weakening of the KEJ can be explained by the reduced atmospheric thermal damping effect on ocean eddies in the absence of OME-A feedback. Analyses of eddy potential energy (EPE) budget show that the suppression of OME-A feedback significantly reduces eddy potential energy dissipation, which is balanced by a reduction in EPE production from the mean flow through baroclinic conversion. The decrease in baroclinic conversion is accomplished through the weakening of the KEJ. This finding highlights the importance of resolving ocean meso-scale eddy-atmosphere feedback in accurately simulating western boundary current regimes in climate models.