Deep Sea Currents Driven by Breaking Internal Tides on the Continental Slope

Mooring data collected on the continental slope of the South China Sea show that along-slope deep sea bottom currents are generated when large spring internal tides (internal waves with tidal frequency) are observed, with the maximum velocity amplitude exceeding 0.15m/s. The observations are consistent with predictions that near-bottom breaking of internal waves can result in generation of along-slope flows when these waves obliquely approach the slope. A linear internal tide model in one horizontal dimension with realistic topography and stratification is used to show that the breaking of internal tides is likely due to near-critical reflection on the slope. Combining the mooring observations and the model simulation, an along-slope near-bottom transport of similar to 0.5Sv is estimated. Along-slope bottom flows caused by breaking internal waves potentially provide a significant way to deform continental slopes and affect deep water exchange between the marginal sea and open ocean.