Preprints
https://doi.org/10.5194/egusphere-2025-3867
https://doi.org/10.5194/egusphere-2025-3867
15 Aug 2025
 | 15 Aug 2025

Cold spells induced by slow and amplified atmospheric waves

Morteza Babaei, Rune Grand Graversen, Johannes Patrick Stoll, and Jakub Petříček

Abstract. Cold spells in the Northern Hemisphere mid-latitudes have been linked to planetary waves. Yet the mechanisms by which these waves impact cold-spell formation remain unclear. Here we develop novel metrics to separately measure the amplitude and speed of ridges and troughs, examining the behavior of planetary waves during winter cold spells. Our findings indicate that while the planetary waves across the entire mid-latitudes experience significant changes during cold spells, local wave dynamics play a major role in developing these events. The nearest upstream ridge and downstream trough of the cold-spell region are located in a way that facilitates development of the extreme cold anomaly. This ridge and trough amplify and slow, enhancing and prolonging southward advection of cold air from the Arctic into the cold-spell region. The slow and amplified upstream ridge and downstream trough occur several days before the region’s minimum temperature, suggesting these local wave anomalies induce cold-spell formation.

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 paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Journal article(s) based on this preprint

20 May 2026
Cold spells induced by slow-moving and amplified large-scale ridge and trough
Morteza Babaei, Rune Grand Graversen, Johannes Patrick Stoll, and Jakub Petříček
Weather Clim. Dynam., 7, 825–841, https://doi.org/10.5194/wcd-7-825-2026,https://doi.org/10.5194/wcd-7-825-2026, 2026
Short summary
Morteza Babaei, Rune Grand Graversen, Johannes Patrick Stoll, and Jakub Petříček

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-3867', Anonymous Referee #1, 18 Sep 2025
    • AC1: 'Reply on RC1', Morteza Babaei, 07 Nov 2025
  • RC2: 'Comment on egusphere-2025-3867', Anonymous Referee #2, 26 Sep 2025
    • AC2: 'Reply on RC2', Morteza Babaei, 07 Nov 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-3867', Anonymous Referee #1, 18 Sep 2025
    • AC1: 'Reply on RC1', Morteza Babaei, 07 Nov 2025
  • RC2: 'Comment on egusphere-2025-3867', Anonymous Referee #2, 26 Sep 2025
    • AC2: 'Reply on RC2', Morteza Babaei, 07 Nov 2025

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
AR by Morteza Babaei on behalf of the Authors (19 Nov 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (08 Dec 2025) by Gwendal Rivière
RR by Anonymous Referee #1 (12 Dec 2025)
RR by Anonymous Referee #2 (15 Jan 2026)
ED: Reconsider after major revisions (20 Jan 2026) by Gwendal Rivière
AR by Morteza Babaei on behalf of the Authors (13 Feb 2026)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (24 Feb 2026) by Gwendal Rivière
RR by Anonymous Referee #1 (25 Feb 2026)
RR by Anonymous Referee #2 (20 Mar 2026)
ED: Publish subject to revisions (further review by editor and referees) (23 Mar 2026) by Gwendal Rivière
AR by Morteza Babaei on behalf of the Authors (01 Apr 2026)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (13 Apr 2026) by Gwendal Rivière
RR by Anonymous Referee #2 (24 Apr 2026)
ED: Publish subject to technical corrections (02 May 2026) by Gwendal Rivière
AR by Morteza Babaei on behalf of the Authors (08 May 2026)  Author's response   Manuscript 

Journal article(s) based on this preprint

20 May 2026
Cold spells induced by slow-moving and amplified large-scale ridge and trough
Morteza Babaei, Rune Grand Graversen, Johannes Patrick Stoll, and Jakub Petříček
Weather Clim. Dynam., 7, 825–841, https://doi.org/10.5194/wcd-7-825-2026,https://doi.org/10.5194/wcd-7-825-2026, 2026
Short summary
Morteza Babaei, Rune Grand Graversen, Johannes Patrick Stoll, and Jakub Petříček
Morteza Babaei, Rune Grand Graversen, Johannes Patrick Stoll, and Jakub Petříček

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Short summary
Extreme weather events have historically caused major challenges for humanity. Yet, our understanding of the mechanisms that contribute to their formation remains unclear. Our study provides evidence that locally amplified and slow-moving planetary waves are responsible for the formation of extreme cold spells. These findings are obtained based on two novel metrics assessing the amplitude and speed of ridges and troughs separately at all longitudes around latitude circles.
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