Distribution and Trend of Wind Power Input to Near-Inertial Motions in the Southern Ocean

Wind power input to near-inertial motions is an important energy source for generating diapycnal mixing in the ocean. However, the distribution and long-term trend of this input over the Southern Ocean have yet to be quantified. In this study, we investigate the near-inertial wind power input (WPIi) to the Southern Ocean using a global eddy-permitting coupled ocean-sea ice model forced by a high-resolution atmospheric reanalysis product. Our results reveal a zonally asymmetric distribution of WPIi in the Southern Ocean, with the strongest input in the South Indian Ocean and the weakest in the South Pacific. The integrated WPIi between 30 & DEG;S and 60 & DEG;S exhibits a significant positive trend over the past four decades due to the intensification of mesoscale weather systems. The surface mixed-layer depth is found to modulate the spatial pattern and trend of WPIi by altering the surface near-inertial currents. Wind fluctuations can excite surface ocean currents that oscillate at frequencies close to the inertial frequency. These near-inertial motions play an important role in generating turbulent mixing in the ocean. However, the distribution and long-term trend of wind power input to near-inertial motions in the Southern Ocean remains unquantified. In this study, we investigate this wind power input using a global ocean circulation model driven by a high-resolution atmospheric reanalysis data set. Our results reveal a pronounced zonal asymmetry in the distribution of near-inertial wind power input in the Southern Ocean. Furthermore, this power input has increased significantly over the past four decades due to the intensification of mesoscale weather systems. Results from this study have important implications for understanding Southern Ocean mixing and circulation. Distribution of near-inertial wind power input in the Southern Ocean is zonally asymmetricNear-inertial wind power input in the Southern Ocean has increased significantly in recent decadesThis increase is primarily driven by the intensification of mesoscale weather systems

Automated summary

This study investigates the distribution and long-term trend of wind power input to near-inertial motions in the Southern Ocean using a global ocean-sea ice model. The results reveal a zonally asymmetric distribution of this power input, with the South Indian Ocean having the strongest input and the South Pacific having the weakest. Furthermore, there is a significant positive trend in this input over the past four decades, primarily driven by the intensification of mesoscale weather systems.