Contrary to what one might think, today’s record levels of fresh water in the Beaufort Sea did not come from melting ice
From the University of Washington press release:
The new findings show that a low pressure pattern created by the Arctic Oscillation from 2005 to 2008 drew Russian river water away from the Eurasian Basin, between Russia and Greenland, and into the Beaufort Sea . . . .
It was like adding 10 feet (3 meters) of freshwater over the central part of the Beaufort Sea.
© 2012 Sandra Hines and Alan Buis, Russian river water unexpected culprit behind Arctic freshening – with video, University of Washington (04 January 2012)
Although the overall salinity of the Arctic Ocean has probably not changed, the ocean’s distribution of fresh water has. The Canadian side is now less saline and the Eurasian side more.
This is reportedly the first time that the Arctic Oscillation has been credited for rerouting Eurasian-sourced river water.
Citation
James Morison, Ron Kwok, Cecilia Peralta-Ferriz, Matt Alkire, Ignatius Rigor, Roger Andersen, and Mike Steele, Changing Arctic Ocean freshwater pathways, Nature 481(7379): 66-70 (05 January 2012)
What is the Arctic Oscillation?
A succinct explanation comes from the National Snow and Ice Data Center:
The Arctic Oscillation refers to opposing atmospheric pressure patterns in northern middle and high latitudes.
The oscillation exhibits a “negative phase” with relatively high pressure over the polar region and low pressure at midlatitudes (about 45 degrees North), and a “positive phase” in which the pattern is reversed.
In the positive phase, higher pressure at midlatitudes drives ocean storms farther north, and changes in the circulation pattern bring wetter weather to Alaska, Scotland and Scandinavia, as well as drier conditions to the western United States and the Mediterranean.
In the positive phase, frigid winter air does not extend as far into the middle of North America as it would during the negative phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual. Weather patterns in the negative phase are in general “opposite” to those of the positive phase, as illustrated below.
Over most of the past century, the Arctic Oscillation alternated between its positive and negative phases.
Starting in the 1970s, however, the oscillation has tended to stay in the positive phase, causing lower than normal arctic air pressure and higher than normal temperatures in much of the United States and northern Eurasia.
© The Arctic Oscillation, National Snow and Ice Data Center <http://nsidc.org/arcticmet/patterns/arctic_oscillation.html> (visited 05 January 2012) (paragraphs split)
Satellites lent a helping hand
Tracking salinity changes by “hand” would have been near impossible. Much of data for this research came from NASA’s ICESat and GRACE satellites.
Note
I’ve written about the Gravity Recovery and Climate Experiment satellites before, here.
ICESat stopped working in 2010.
The satellites provided ocean height and bottom pressure information. The research team was then able to separate “changes in mass from changes in density” — from which (the less dense) fresh water movement in the water column could be inferred.
How accurate that inference is remains to be seen. But the research team implies that their inferences closely agreed with salinity measurements taken on site.
“To me it’s pretty spectacular that you have these satellites zipping around hundreds of kilometers above the Earth and they give us a number about salinity that’s very close to what we get from lowering little sampling bottles into the ocean,” [James} Morison said.
© 2012 Sandra Hines and Alan Buis, Russian river water unexpected culprit behind Arctic freshening – with video, University of Washington (04 January 2012)
Spectacular, indeed.
Tagged: Alan Buis, Arctic Ocean, Arctic Oscillation, Beaufort Sea, Cecilia Peralta-Ferriz, Eurasian, fresh water, freshwater, grace, Gravity Recovery and Climate Experiment, ICESat, Ignatius Rigor, James Morison, Matt Alkire, Mike Steele, river, Roger Andersen, Ron Kwok, Russian, salinity, Sandra Hines