Seasonal to Interannual Variation of the Beaufort Shelfbreak Jet Using Two Decades of Mooring Data, 2002–2022

Abstract The shelfbreak jet of the Beaufort Sea is the main conduit of Pacific water progressing eastward from the Chukchi shelf, delivering heat, freshwater, and nutrients that impact the hydrographic state and ecosystem of the western Arctic Ocean. A mooring has been maintained in the center of the jet since 2002 (with a few gaps). Here we use this long timeseries to quantify the seasonal signal in water mass properties and transport of the jet and explore the interannual variability. The annual mean transport is 0.064 ± 0.018 Sv over the 20‐year period. It is largest during summer and decreases to near zero during the remainder of the year. Early in the record there was a single transport peak in July, but in recent years a second peak has occurred in October. Warm water first appears at the mooring site in July and lasts until December, after which winter water is the prevalent water mass advected by the jet. Using timeseries of ice thickness from the mooring, satellite ice concentration, and weather station wind data, we demonstrate that the transport of the shelfbreak jet is significantly reduced due to the combination of wind and ice cover. The reduction is greatest in the spring and fall when the pack‐ice is more mobile. The strength of the jet, and the fluxes of the individual water masses it advects, display pronounced interannual variability. The dominant year‐to‐year changes in transport are due to changes in the undisturbed transport; that is, in the absence of local winds.