Retreat of the Cold Halocline Layer in the Arctic Ocean
Michael Steele
Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, 98105 USA
Tel: 1-206-543-6586
Fax: 1-206-543-3521
mas@apl.washington.edu
Timothy Boyd
College of Oceanic and Atmospheric Sciences, Oregon State University
Corvallis,OR 97330 USA
We present a comparison of Arctic Ocean hydrographic data sets from the 1990's, with a focus on changes in the upper few hundred meters of the Eurasian Basin. These comparisons reveal that the Eurasian Basin "cold halocline layer" has retreated during the 1990's to cover significantly less area than in previous years. Specifically, we find a retreat from the Amundsen Basin back into the Makarov Basin; the latter is the only region with a true cold halocline layer during SCICEX'95. Changes are also seen in other halocline types and in the Atlantic Water layer heat content and depth. The overall cause of water mass changes in the 1990's might have been a shift in the atmospheric wind forcing and resulting sea ice motion during the late 1980's, which we speculate influenced the location where fresh shelf waters flow into the deeper basins of the Arctic Ocean. Finally, we discuss two different mechanisms that have been proposed for cold halocline water formation, and propose a new compromise that best fits these data.
