Mean and Time Dependent Circulation of the Eastern Chukchi Sea from Moored Timeseries in 2013-14

Fei Tian1, Robert S Pickart2, Peigen Lin2, Bridget Ovall2, Phyllis J Stabeno3, Thomas Weingartner4, Motoyo Itoh5, Takashi Kikuchi5, Elizabeth L Dobbins4, Shaun W Bell3, Rebecca A Woodgate6 and Zhaomin Wang7, (1)Hohai University, China, (2)Woods Hole Oceanographic Institution, Woods Hole, MA, United States, (3)NOAA Pacific Marine Environmental Laboratory, Seattle, WA, United States, (4)University of Alaska Fairbanks, College of Fisheries and Ocean Sciences, Fairbanks, AK, United States, (5)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (6)Univ Washington, Seattle, WA, United States, (7)Hohai University, College of Oceanography, Nanjing, China
From summer 2013 to summer 2014 there was extraordinary coverage of the eastern Chukchi Sea with moorings as a result of multiple observational programs. Here we analyze hydrographic and velocity timeseries from 20 moorings extending from Bering strait to the outer Chukchi shelf to quantify the mean and seasonally-varying flow, as well as the response to storms. The mean vectors depict strong surface-intensified northward flow through Bering Strait and Barrow Canyon, and weaker, more barotropic flow that circulates to the north and south of Hanna Shoal before feeding Barrow Canyon. This pattern is remarkably consistent with a previous compilation using shipboard velocity data. Temperature signals propagate northward from Bering Strait along these pathways, consistent with the calculated advective timescales. However, the salinity signals do not follow this pattern, but instead are influenced by local polynya activity across the shelf. The flow throughout the Chukchi Sea is stronger during the summer months (May-August) and weaker during the winter months (December-March). The coastal pathway is sensitive to alongcoast winds, while the circulation on the interior shelf is dictated more by wind stress curl. Using atmospheric reanalysis data we identified all of the storms over the year, and the transient response of the circulation to these wind events is explored.