The effect of Stokes drift on Ekman transport in the open sea

By introducing the wave-induced Coriolis-Stokes forcing into ageostrophic motion equation, the Eulerian transport is modified by the wave-induced Stokes drift. The long-term mean contributions of the Stokes transport with remotely generated swells being included to the ageostrophic transport are analyzed using the ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis data. The ratio of Stokes transport to Ekman transport in north-south (N-S) direction can reach a maximum of over 50% in the subtropical region. The preliminary influence of the Stokes transport on the North Pacific gyre is all year persistent, while the effect on the North Atlantic gyre is only obvious in boreal winter and early spring.