Dramatic Weakening of the Pacific Water Boundary Current in the Beaufort Sea during the First Decade of the 2000s.

Friday, 19 December 2014: 4:45 PM
Robert S Pickart1, Eric Brugler1, Kent Moore2, Steve Roberts3, Thomas Weingartner3 and Hank Statscewich3, (1)WHOI, Woods Hole, MA, United States, (2)Univ Toronto, Toronto, ON, Canada, (3)University of Alaska Fairbanks, Fairbanks, AK, United States
Pacific-origin water has profound impacts on the physical state and
ecosystem of the Western Arctic Ocean. The cold winter water
ventilates the upper halocline and supplies nutrients that fuel
primary productivity, while the warm summer waters melt sea ice and
supply freshwater to the Beaufort Gyre. Here we use mooring data
collected as part of the Arctic Observing Network (AON) to examine the
interannual trends in the current over the period 2002-2011.
Strikingly, the volume transport of the current has decreased by more
than 80%, despite the fact that the flow through Bering Strait has
increased over this time period. The largest changes have occurred in
the summer months. Using atmospheric reanalysis fields and weather
station data, we demonstrate that an increase in summer easterly winds
is the primary cause for the reduction in transport, which is largely
dictated by the behavior of the two atmospheric centers of action, the
Beaufort High and Aleutian Low. Using additional mooring and shipboard
data, together with satellite fields, we argue that a significant
portion of the mass and heat passing through Bering Strait in recent
years has been advected out of Barrow Canyon into the interior Canada
Basin - rather than entering the boundary current in the Beaufort Sea
- where it is responsible for a significant portion of the increased
sea ice melt in the basin.