| Autor: |
Narayanan A; Department of Marine Science, University of Gothenburg, Gothenburg, Sweden.; Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, UK., Roquet F; Department of Marine Science, University of Gothenburg, Gothenburg, Sweden., Gille ST; Scripps Institution of Oceanography, University of California, San Diego, San Diego, CA, USA., Gülk B; Department of Marine Science, University of Gothenburg, Gothenburg, Sweden., Mazloff MR; Scripps Institution of Oceanography, University of California, San Diego, San Diego, CA, USA., Silvano A; Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, UK., Naveira Garabato AC; Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, UK. |
| Abstrakt: |
Open-ocean polynyas formed over the Maud Rise, in the Weddell Sea, during the winters of 2016-2017. Such polynyas are rare events in the Southern Ocean and are associated with deep convection, affecting regional carbon and heat budgets. Using an ocean state estimate, we found that during 2017, early sea ice melting occurred in response to enhanced vertical mixing of heat, which was accompanied by mixing of salt. The melting sea ice compensated for the vertically mixed salt, resulting in a net buoyancy gain. An additional salt input was then necessary to destabilize the upper ocean. This came from a hitherto unexplored polynya-formation mechanism: an Ekman transport of salt across a jet girdling the northern flank of the Maud Rise. Such transport was driven by intensified eastward surface stresses during 2015-2018. Our results illustrate how highly localized interactions between wind, ocean flow and topography can trigger polynya formation in the open Southern Ocean. |
