Intermittency in Wave-breaking Turbulence and Impacts on the Predictability of the Ocean Surface Layer

Surface gravity waves are a critical concern for marine safety and security. Wave breaking episodically injects bursts of turbulent kinetic energy into the upper ocean. At the same time, wind stress drives continuous turbulence production through shear. Despite its importance for a wide range of processes like gas-transfer rates and underwater sound levels, a reliable model for turbulence generation at the wavy ocean surface is still a subject for active research. This proposal seeks to leverage recent technological and methodological advancements to make low cost, sustained measurements of turbulence near the ocean surface at sufficiently high vertical and temporal resolution to attribute estimates of the turbulent kinetic energy dissipation directly to breaking waves. The results of this project are expected to inform models of upper ocean processes including air-sea interactions which are of prime importance for weather, ocean, and marine forecasting. The proposed work will improve understanding of elevated turbulent dissipation rates in the presence of surface wave breaking and bubbles. The results will reconcile intermittent turbulence in the surface ocean layer with ensemble-average interpretations of steady-state theoretical turbulence. Turbulence and potential biases will be related to wind and wave state variables measured in the long-term records at Station Papa. A new regime diagram will describe when and where the distinct turbulence theories apply. This will enable improved estimation of air-sea exchange. Turbulence observations will be obtained using Acoustic Doppler Current Profilers mounted on Surface Wave Instrument Floats with Tracking deployed at Ocean Station Papa. The project also includes state-of-the-art modeling methods in tandem with the observations. The proposed work will advance methods for measuring turbulence and underwater sound near the ocean surface. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.