Internal tidal mean flow in the upper circulation of a marginal sea

Internal tides are significant in marginal seas, primarily focusing on dissipation-induced mixing; however, the mean flow from nonlinearity is less explored. Lagrangian mean flow driven by M2 internal tide was calculated in the upper South China Sea (SCS), with a magnitude of O(10−2) m/s. This mean flow constitutes roughly 10% of the circulation according to the HYbrid Coordinate Ocean Model, primarily distributed along the continental slope and basin margin, demonstrating significant nonlinearity and highlighting topographic influence on the mean flow generation. These findings suggest that internal tidal mean flow may significantly influence SCS circulation, warranting further study.