Variability and trends in Southern Ocean eddy activity in 1/12° ocean model simulations

The response of eddy kinetic energy (EKE) to the strengthening of Southern Hemisphere winds occurring since the 1950s is investigated with a global ocean model having a resolution of 1/12 degrees in the Antarctic Circumpolar Current domain. The simulations expose regional differences in the relative importance of stochastic and wind-related contributions to interannual EKE changes. In the Pacific and Indian sectors the model captures the EKE variability observed since 1993 and confirms previous hypotheses of a lagged response to regional wind stress anomalies. Here the multidecadal trend in wind stress is reflected in an increase in EKE typically exceeding 5 cm(2) s(-2) decade(-1). In the western Atlantic, EKE variability is mostly stochastic, is weakly correlated with wind fluctuations, and its multidecadal trends are close to zero. The nonuniform distribution of wind-related changes in the eddy activity could affect the regional patterns of ocean circulation and biogeochemical responses to future climate change.