Burst events of near-inertial waves in the Beaufort Sea

Abstract

Based on moored observations from the Beaufort Gyre Exploration Project, seven burst events of near-inertial waves (NIWs) during September 2017-September 2018 are investigated in this study. These NIW events are divided into two groups. Four NIW events in group I are dominated by downgoing components associated with near-inertial currents in the magnitude of about 0.1 m/s. The plane-wave fitting results indicate that these NIWs have much smaller vertical wavelengths and energy fluxes than those in the mid-latitude oceans. By performing simulations with the slab model and analyzing sea ice conditions, we find that one NIW event is directly excited by the wind in the ice-free summer of 2018. Whereas, the other three NIW events are likely induced by the ice motion. For NIWs in group II, the downgoing and upgoing components are comparable in strength. The downgoing NIWs could be directly forced by the wind; whereas the upgoing ones may be related to the eddy events.The occurrence of the NIW events caused strong shears and hence smaller Richardson number, further resulting in the elevation of the energy dissipation rate. Results of this study can improve our understanding on the NIW dynamics and their influence on the mixing in the Arctic Ocean.