Preprints
https://doi.org/10.5194/wcd-2021-79
https://doi.org/10.5194/wcd-2021-79
 
06 Dec 2021
06 Dec 2021
Status: a revised version of this preprint is currently under review for the journal WCD.

North Atlantic freshwater events influence European weather in subsequent summers

Marilena Oltmanns1, N. Penny Holliday1, James Screen2, D. Gwyn Evans1, Simon A. Josey1, Sheldon Bacon1, and Ben I. Moat1 Marilena Oltmanns et al.
  • 1National Oceanography Centre, Southampton, UK
  • 2University of Exeter, Exeter, UK

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.

Marilena Oltmanns et al.

Status: final response (author comments only)

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 et al.

Marilena Oltmanns et al.

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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.