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  • 2020 Weakening of cold halocline layer exposes sea ice to oceanic heat in the eastern Arctic 2 Ocean

    Final published version, 2.14 MB, PDF document

    Embargo ends: 10/01/21

    Licence: Other

DOI

  • Igor Polyakov
    University of Alaska Fairbanks
  • Tom Rippeth
  • Ilker Fer
    University of Bergen
  • Matthew Alkire
    University of Washington
  • Till Baumann
    University of Alaska Fairbanks
  • Eddy Carmack
    Fisheries and Oceans Canada
  • Vladimir Ivanov
    Arctic and Antartic Research Institute
  • M.A. Janout
    Alfred Wegener Institute for Polar and Marine Research
  • Laurie Padman
    Earth & Space Research
  • Andrey Pnyushkov
    University of Alaska Fairbanks
  • Robert Rember
    University of Alaska Fairbanks
A 15-year duration record of mooring observations from the eastern (>70oE) Eurasian Basin (EB) of the Arctic Ocean is used to show and quantify the recently increased oceanic heat flux from intermediate-depth (~150-900 m) warm Atlantic Water (AW) to the surface mixed layer (SML) and sea ice. The upward release of AW heat is regulated by the stability of the overlying halocline, which we show has weakened substantially in recent years. Shoaling of the AW has also contributed, with observations in winter 2017-2018 showing AW at only 80 m depth, just below the wintertime surface mixed layer (SML), the shallowest in our mooring records. The weakening of the halocline for several months at this time implies that AW heat was linked to winter convection associated with brine rejection during sea ice formation. This resulted in a substantial increase of upward oceanic heat flux during the winter season, from an average of 3-4 W/m2 in 2007-2008 to >10 W/m2 in 2016-2018. This seasonal AW heat loss in the eastern EB is equivalent to a more than a two-fold reduction of winter ice growth. These changes imply a positive feedback as reduced sea ice cover permits increased mixing, augmenting the summer-dominated ice-albedo feedback.

Keywords

  • Arctic Sea Ice, atlantification
Original languageEnglish
Pages (from-to)8107-8123
JournalJournal of Climate
Volume33
Issue number18
Early online date10 Jul 2020
DOIs
Publication statusPublished - 15 Sep 2020
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