Wave‐driven along‐channel subtidal flows in a well‐mixed ocean inlet

Observations of waves, flows, and water levels collected for a month in and near a long, narrow, shallow (∼ 3000 m long, 1000 m wide, and 5 m deep), well‐mixed ocean inlet are used to evaluate the subtidal (periods > 30 h) along‐inlet momentum balance. Maximum tidal flows in the inlet were about 1.5 m/s and offshore significant wave heights ranged from about 0.5 to 2.5 m. The dominant terms in the local (across the km‐wide ebb shoal) along‐inlet momentum balance are the along‐inlet pressure gradient, the bottom stress, and the wave radiation‐stress gradient. Estimated nonlinear advective acceleration terms roughly balance in the channel. Onshore radiation‐stress gradients owing to breaking waves enhance the flood flows into the inlet, especially during storms.