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Air-sea interactions and water mass transformation during a katabatic storm in the Irminger Sea
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  • Oliver Gutjahr,
  • Johann H Jungclaus,
  • Nils Brüggemann,
  • Helmuth Haak,
  • Jochem Marotzke
Oliver Gutjahr
Universität Hamburg

Corresponding Author:oliver.gutjahr@uni-hamburg.de

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Johann H Jungclaus
Max Planck Institute for Meteorology
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Nils Brüggemann
University of Hamburg
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Helmuth Haak
Max-Planck-Institut fuer Meteorologie
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Jochem Marotzke
Max Planck Institute for Meteorology
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We use a global 5-km resolution model to analyse the air-sea interactions during a katabatic storm in the Irminger Sea originating from the Ammassalik valleys. Katabatic storms have not yet been resolved in global climate models, raising the question of whether and how they modify water masses in the Irminger Sea. Our results show that dense water forms along the boundary current and on the shelf during the katabatic storm due to the heat loss caused by the high wind speeds and the strong temperature contrast. The dense water contributes to the North Atlantic Deep Water and thus to the Atlantic Meridional Overturning Circulation (AMOC). The katabatic storm triggers a polar low, which in turn amplifies the near-surface wind speed in a positive feedback, in addition to acceleration from a breaking mountain wave. Resolving katabatic storms in global models is therefore important for the formation of dense water in the Irminger Sea, which is relevant to the AMOC, and for the large-scale atmospheric circulation by triggering polar lows.
May 2022Published in Journal of Geophysical Research: Oceans volume 127 issue 5. 10.1029/2021JC018075