Barrow Canyon, in the northeast Chukchi Sea, is a major conduit for Pacific Water to enter the interior Arctic basins. Assemblies of annual (September 2000 to August 2008) temperature, salinity, and velocity data acquired from a mooring array in the mouth of Barrow Canyon and high‐resolution hydrographic and velocity transects along the mooring array in 2002, 2010, and 2011 have enabled a direct computation of volume, heat, and freshwater fluxes. Annual mean volume transport through Barrow Canyon was 0.45 Sv, which consisted of 0.44 Sv of Pacific Water and 0.01 Sv of Atlantic Water. Annual mean Pacific Water transport through Barrow Canyon represents 55% of the long‐term mean Pacific Water inflow through the Bering Strait. During summer, more of the Pacific inflow was advected to an eastern path as the Alaskan Coastal Current that flows along the Alaskan coast to Barrow Canyon. The freshwater flux through Barrow Canyon was 904 km3/yr, which is equivalent to 5% of the freshwater content of the Canada Basin. The annual averaged heat flux displayed substantial interannual variability, ranging from 0.93 to 3.02 TW, which could melt 88,000–290,000 km2 of 1 m thick ice. A relationship exists between the measured Barrow Canyon transport and local winds such that under southerly winds the northward flow of water through the canyon increases. Such wind conditions are induced by the weaker sea level pressure contrast between the Arctic and North Pacific, caused by a decrease in the pressure over the Arctic and an increase over the North Pacific.

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A fixed-point observation station was set up in the northern Chukchi Sea during autumn 2013, and for about 2 weeks conductivity-temperature-depth (CTD)/water samplings (6 h) and microstructure turbulence measurements (2 to 3 times a day) were performed. This enabled us to estimate vertical nutrient fluxes and the impact of different types of turbulent mixing on biological activity. There have been no such fixed-point observations in this region, where incoming low-salinity water from the Pacific Ocean, river water, and sea-ice meltwater promote a strong pycnocline (halocline) that stabilizes the water column. Previous studies have suggested that because of the strong pycnocline, wind-induced ocean mixing could not change the stratification to impact biological activity. However, the present study indicates that a combined effect of an uplifted pycnocline accompanied by wind-induced inertial motion and turbulent mixing caused by intense gale-force winds (>10 m s 21 ) did result in increases in upward nutrient fluxes, primary productivity, and phytoplankton biomass, particularly large phytoplankton such as diatoms. Convective mixing associated with internal waves around the pycnocline also increased the upward nutrient fluxes and might have an impact on biological activity there. For diatom production at the fixed-point observation station, it was essential that silicate was supplied from a subsurface silicate maximum, a new feature that we identified during autumn in the northern Chukchi Sea. Water mass distributions obtained from wide-area observations suggest that the subsurface silicate maximum water was possibly derived from the ventilated halocline in the Canada Basin.