ARCtic Ocean Mixing: Influence of changing ice cover on internal waves and mixing

The proposal is motivated by recent findings showing i) the sensitivity of Arctic Ocean circulation to background deep-ocean diapycnal mixing and ii) enhancement of near-inertial internal wave activity and induced mixing in the absence of sea ice. Mixi ng in the stratified ocean is related to internal wave energy, which tends to be low under the Arctic Ocean ice cover. Consequently, as ice cover declines, background mixing may increase and, among other changes, bring more Atlantic Water heat to the surf ace to melt ice, a potentially important positive climate feedback. To understand the influence of background mixing and to improve models of the changing Arctic Ocean, we will take advantage of the latest analysis techniques to examine existing internal wave and mixing data and thereby develop a database with which to track changes in the internal wave and mixing environments. We will combine new observations with recent and historical data, including data north of Svalbard particularly around the Yermak Plateau, to explore the energetics of Arctic internal waves and mixing under changing ice conditions. The goals of this study cannot be achieved without the strong US-Norway collaboration proposed here. The collaborator James Morison (University of Washi ngton) has already received support for a sister project from NSF in USA. The project compiles with the theme on "Oceanography and geophysics (melting and freezing of sea ice, Atlantic studies and interior variability mapping, process studies, regional cl imate simulation-impact studies)" of the call. The proposal strengthens the North Pole Environmental Observatory activity and builds directly on data, results and expertise achieved from recent RCN-funded projects: Current measurements north of Svalbard ( 2007-2009, Polres, NOR-USA, PI: Haugan, co-PI: Fer) and Ocean Mixing in the Arctic (2007-2008, NORKLIMA Young Investigator grant, PI: Fer).