Flow Patterns over the Chukchi Continental Shelf : 2010-2019

From 2010 to 2019, moorings were deployed on the Chukchi Sea at a dozen sites. Deployment duration varied from 9 years at a site off Icy Cape to a singleyear at a site north of Hanna Shoal. Currents were measured at each site, usually with Acoustic Doppler Current Profilers (ADCPs). In addition, a total of 45 satellite-tracked drifters (drogue depth 25–30 m) and 32 ALAMO floats were deployed in the region during 2012– 2018. Together, these data provided insight into the temporal and spatial variability in the currents over eastern Chukchi continental shelf. The north-south pressure gradient results in, on average, a northward flow over the Chukchi shelf, which is modified by local winds. There is a 9-year time series of transport at Icy Cape, which accounts for most of the northeastward flow in Barrow Canyon. The annual volume transport near Icy Cape ranged from 0.30 Sv (September 2011 – August 2012) to 0.70 Sv (September 2017 – August 2018), with a 9-year average of 0.42 Sv. This transport accounts for approximately 40% of the flow through Bering Strait and varies seasonally, ranging from >50% of summer transport to only 20% of winter transport in Bering Strait. Anomalous winds toward the north-northeast in the winter of 2017/2018 likely contributed to the higher annual transports in September 2017-August 2018. There are two years(2017-2018 and 2018-2019)of more intense spatial sampling. Current measurements were made at 8-9 locations on the eastern Chukchi Sea: southern Chukchi (1 mooring), Central Channel (2 moorings), Icy Cape (3-4 moorings) and Barrow Canyon (2 moorings). These measurements provide insight into patterns of flow across this shelf. Measurements of transport at Icy Cape and in Central Channel indicate that most of the transport at Icy Cape is a continuation of the flow in Central Channel.