Mesoscale eddies are important for many aspects of the dynamics of the Arctic Ocean. These include the maintenance of the halocline and the Atlantic Water boundary current through lateral eddy fluxes, shelf-basin exchanges, transport of biological material and sea ice, and the modification of the sea-ice distribution. Here we review what is known about the mesoscale variability and its impacts in the Arctic Ocean in the context of an Arctic Ocean responding rapidly to climate change. In addition, we present the first quantification of eddy kinetic energy (EKE) from moored observations across the entire Arctic Ocean, which we compare to output from an eddy resolving numerical model. We show that EKE is largest in the northern Nordic Seas/Fram Strait and it is also elevated along the shelfbreak of the Arctic Circumpolar Boundary Current, especially in the Beaufort Sea. In the central basins it is 100-1000 times lower. Except for the region affected by southward sea-ice export south of Fram Strait, EKE is stronger when sea-ice concentration is low compared to dense ice cover. Areas where conditions typical in the Atlantic and Pacific prevail will increase. Hence, we conclude that the future Arctic Ocean will feature more energetic mesoscale variability.This table provides (eddy) kinetic energy in the Arctic Ocean calculated from moorings and a numerical model across the entire record and averaged over certain conditions (seasons, ice concentration). The calculations are explained in the manuscript (Eddies and the distribution of eddy kinetic energy in the Arctic Ocean). The used mooring data was compiled from six different sources as listed below and identified in the table based on the Source ID.

This table provides (eddy) kinetic energy in the Arctic Ocean calculated from moorings and a numerical model across the entire record and averaged over certain conditions (seasons, ice concentration). The calculations are explained in the manuscript (Eddies and the distribution of eddy kinetic energy in the Arctic Ocean). The used mooring data was compiled from six different sources as listed below and identified in the table based on the Source ID.Source ID list:1. Baumann et al. compilation for tidal parameters: https://www.nature.com/articles/s41597-020-00578-z/tables/32. Global Multi-Archive Current Meter Database: http://mespages.univ-brest.fr/~scott/GMACMD/gmacmd.html3. Pangaea:von Appen et al. 2016-2018 FRAM https://doi.org/10.1594/PANGAEA.904565von Appen et al. 1997-2016 Fram Strait https://doi.org/10.1594/PANGAEA.900883Schaffer et al. 2016-2018 EG shelf https://doi.org/10.1594/PANGAEA.909471Karasik 2015-2016 https://doi.org/10.1594/PANGAEA.870849Nansen 2015-2016 https://doi.org/10.1594/PANGAEA.8708504. Arctic Data Center:BS3 Arctic Observing Network 2002-2003 https://doi.org/10.18739/A24T6F334 BS3 Arctic Observing Network 2003-2004 https://doi.org/10.18739/A2222R59X BS3 Arctic Observing Network 2005-2006 https://doi.org/10.18739/A2FB4WM1G BS3 Arctic Observing Network 2008-2009 https://doi.org/10.18739/A25T3G02W BS3 Arctic Observing Network 2009-2010 https://doi.org/10.18739/A29W09071 BS3 Arctic Observing Network 2010-2011 https://doi.org/10.18739/A2GH9B984 BS3 Arctic Observing Network 2011-2012 https://doi.org/10.18739/A2BR8MH3H BS3 Arctic Observing Network 2012-2013 https://doi.org/10.18739/A2707WP8K BS3 Arctic Observing Network 2013-2014 https://doi.org/10.18739/A23775W4T BS3 Arctic Observing Network 2014-2016 https://doi.org/10.18739/A29K45S73 BS3 Arctic Observing Network 2016-2018 https://doi.org/10.18739/A2ZG6G7975. Woods Hole Oceanographic Institution website:Bureau of Ocean Energy Management Arctic Moorings 2013-2014 http://science.whoi.edu/users/seasoar/boem_recov/Beaufort Gyre Exploration Project moorings 2003-2018 https://www2.whoi.edu/site/beaufortgyre/data/mooring-data/ 6. Personal communication (data not yet available online)Arctic Kap moorings 2015-2018 Eugenio.Ruiz-Castillo@awi.de