Abstract:

To reveal the spatial and temporal distribution patterns of internal wave-induced mixing in global ocean and investigate its influencing factors, this study employs an internal wave fine-scale parameterization method to statistically analyze Argo temperature and salinity data at 250-500 m depth from 2006 to 2021. The analysis characterizes the spatial and temporal features of internal wave mixing and identifies the impact of wind-induced near-inertial energy flux on mixing across global oceans under varying seasonal conditions. In space, there is strong wind-induced near-inertial energy flux in the four seasons of the North Atlantic and Southern Ocean in the whole year, resulting in significant internal wave mixing. However, in the western Pacific and the north of 40°N in the North Pacific, the spatial distribution of internal wave-induced mixing are inconsistent with the wind-induced near-inertial energy flux. Instead, it follows the spatial distribution of eddy kinetic energy since internal wave-driven mixing can be also regulated by eddies. In terms of time, the strongest internal wave-induced mixing of global occurs from December to February, followed by September to November and March to May, and June to August. This is consistent with the seasonal variation of global wind-induced near-inertial energy flux. In the northern hemisphere, the wind-induced near-inertial energy flux and mixing are the strongest in winter, while the weakest in summer. In the southern hemisphere, the variation of wind-induced near-inertial energy flux and mixing over four seasons is inconsistent. However, the seasonal cycles of mixing and wind-induced near-inertial energy flux in the northern and southern hemispheres are roughly consistent, especially in the North Atlantic, where the wind-induced near-inertial energy flux and mixing match well.

Key words: internal wave-induced mixing, diffusivity, dissipation rate, wind-induced near-inertial energy flux, eddy kinetic energy, fine-scale parameterization, Argo, global