A description of local and nonlocal eddy-mean flow interaction in a global eddy-permitting state estimate

Abstract

The assumption that local baroclinic instability dominates eddy-mean flow interactions is tested on a global scale using a dynamically consistent eddy-permitting state estimate. Interactions are divided into local and nonlocal. If all the energy released from the mean flow through eddy-mean flow interaction is used to support eddy growth in the same region, or if all the energy released from eddies through eddy-mean flow interaction is used to feed back to the mean flow in the same region, eddy-mean flow interaction is local; otherwise, it is nonlocal. Different regions have different characters: in the subtropical region studied in detail, interactions are dominantly local. In the Southern Ocean and Kuroshio and Gulf Stream Extension regions, they are mainly nonlocal. Geographical variability of dominant eddy-eddy and eddy-mean flow processes is a dominant factor in understanding ocean energetics.