Non-Linear Internal Waves Pulse Cold Water Into the Shallow Inner-Shelf and Surfzone

Gregory Sinnett, Falk Feddersen, Drew Lucas, Geno Pawlak, Eric Terrill
VIII th Int. Symp. on Stratified Flows   unpublished
Non-linear internal waves (NLIW) are known to transport cold, nutrient rich water into the shallow inner-shelf. However, the evolution of NLIWs into the very shallow nearshore environment (< 15 m) has not been well resolved. Here, we present new observations of NLIW in water < 15 m using a dense array of thermistors and ADCPs to track NLIW propagation all the way to the shore. Multi-day periods of enhanced internal wave activity were observed, with oscillations at semi-diurnal (12 h) and first
more » ... l (12 h) and first harmonic (6 h) periods surging cold water inshore at a variety of different angles. Temperature variations as large as 2 • C in 30 min, and at periods sometimes < 9 min were associated with internal wave events in water as shallow as 7 m. Occasionally, NLIWs were observed to propagate all the way to the surfzone, temporarily decreasing the water temperature by as much as 3 degrees in 1 m water depth, and leaving a residual cooling signature that persisted long after the end of the internal wave event.