Preprints
https://doi.org/10.5194/wcd-2021-79
https://doi.org/10.5194/wcd-2021-79
06 Dec 2021
 | 06 Dec 2021
Status: this preprint was under review for the journal WCD but the revision was not accepted.

North Atlantic freshwater events influence European weather in subsequent summers

Marilena Oltmanns, N. Penny Holliday, James Screen, D. Gwyn Evans, Simon A. Josey, Sheldon Bacon, and Ben I. Moat

Abstract. Amplified Arctic ice loss in recent decades has been linked to increased occurrence of extreme mid-latitude weather. The underlying dynamical mechanisms remain elusive, however. Here, we demonstrate a novel mechanism linking freshwater releases into the North Atlantic with summer weather in Europe. Combining remote sensing, atmospheric reanalyses and model simulations, we show that freshwater events in summer trigger progressively sharper sea surface temperature gradients in subsequent winters, destabilising the overlying atmosphere and inducing a northward shift in the North Atlantic Current. In turn, the jet stream over the North Atlantic is deflected northward in the following summers, leading to warmer and drier weather over Europe. Our results suggest that growing Arctic freshwater fluxes will increase the risk of heat waves and droughts over the coming decades, and could yield enhanced predictability of European summer weather, months to years in advance.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Marilena Oltmanns, N. Penny Holliday, James Screen, D. Gwyn Evans, Simon A. Josey, Sheldon Bacon, and Ben I. Moat

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on wcd-2021-79', Anonymous Referee #1, 06 Jan 2022
  • RC2: 'Comment on wcd-2021-79', Anonymous Referee #2, 26 Jan 2022
  • RC3: 'Comment on wcd-2021-79', Anonymous Referee #3, 05 Feb 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on wcd-2021-79', Anonymous Referee #1, 06 Jan 2022
  • RC2: 'Comment on wcd-2021-79', Anonymous Referee #2, 26 Jan 2022
  • RC3: 'Comment on wcd-2021-79', Anonymous Referee #3, 05 Feb 2022
Marilena Oltmanns, N. Penny Holliday, James Screen, D. Gwyn Evans, Simon A. Josey, Sheldon Bacon, and Ben I. Moat
Marilena Oltmanns, N. Penny Holliday, James Screen, D. Gwyn Evans, Simon A. Josey, Sheldon Bacon, and Ben I. Moat

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Latest update: 20 Jun 2024
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Short summary
The Arctic is currently warming twice as fast as the global average. This results in enhanced melting and thus freshwater releases into the North Atlantic. Using a combination of observations and models, we show that atmosphere-ocean feedbacks initiated by freshwater releases into the North Atlantic lead to warmer and drier weather over Europe in subsequent summers. The existence of this dynamical link suggests that European summer weather can potentially be predicted months to years in advance.