Preprints
https://doi.org/10.5194/egusphere-2024-3924
https://doi.org/10.5194/egusphere-2024-3924
18 Dec 2024
 | 18 Dec 2024

Saharan dust linked to European hail events

Killian P. Brennan and Lena Wilhelm

Abstract. Saharan dust significantly influences hail occurrence in Europe. Using Copernicus Atmosphere Monitoring Service (CAMS) and reanalysis data, crowd-sourced hail reports, lightning data, and radar measurements, we find a strong correlation between elevated dust loading and hail events. Hail coverage exceeding 28 % of 1°×1° grid cells only occurs when dust loading surpasses 2.4 mg m−2, while on hail days the median dust load is 1.82 times higher than on non-hail days (7σ difference). This effect is particularly strong along the Alpine crest, central France, eastern Germany, Austria, and Eastern Europe, where median dust loads more than double on hail days.

By grouping data according to synoptic weather patterns, we confirm that hail days consistently exhibit higher dust concentrations regardless of prevailing synoptic conditions, supporting the robust link between dust and hail. Peak hail activity occurs at 38 mg m−2 or a dust optical depth of 0.033, suggesting enhanced cloud and ice nucleation. Above this range, hail frequency declines, likely due to microphysical or radiative constraints.

Crowd-sourced reports show significantly more hail events on high-dust days, with up to 10 times more reports for hail >20 mm. Statistical hail models, including a logistic regression model (LRM) and a generalized additive model (GAM), rank dust as one of the top three predictors. Its inclusion increases the critical success index (CSI) by 5 % (LRM) and 12 % (GAM), and boosts explained variance in the GAM by 6 %. These findings identify Saharan dust as a key modulator of European hail activity.

Competing interests: The contact author has declared that neither of the authors has any competing interests.

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

19 Sep 2025
Saharan dust linked to European hail events
Killian P. Brennan and Lena Wilhelm
Atmos. Chem. Phys., 25, 10823–10836, https://doi.org/10.5194/acp-25-10823-2025,https://doi.org/10.5194/acp-25-10823-2025, 2025
Short summary
Killian P. Brennan and Lena Wilhelm

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3924', Anonymous Referee #1, 23 Feb 2025
  • AC1: 'Comment on egusphere-2024-3924', Killian Brennan, 26 Feb 2025
  • RC2: 'Comment on egusphere-2024-3924', Anonymous Referee #2, 02 Jun 2025
  • AC2: 'Comment on egusphere-2024-3924', Killian Brennan, 07 Aug 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3924', Anonymous Referee #1, 23 Feb 2025
  • AC1: 'Comment on egusphere-2024-3924', Killian Brennan, 26 Feb 2025
  • RC2: 'Comment on egusphere-2024-3924', Anonymous Referee #2, 02 Jun 2025
  • AC2: 'Comment on egusphere-2024-3924', Killian Brennan, 07 Aug 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Killian Brennan on behalf of the Authors (26 Jun 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (03 Jul 2025) by Marco Gaetani
RR by Anonymous Referee #2 (14 Jul 2025)
RR by Anonymous Referee #1 (18 Jul 2025)
ED: Reconsider after major revisions (21 Jul 2025) by Marco Gaetani
AR by Killian Brennan on behalf of the Authors (21 Jul 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (22 Jul 2025) by Marco Gaetani
RR by Anonymous Referee #1 (05 Aug 2025)
ED: Publish subject to technical corrections (07 Aug 2025) by Marco Gaetani
AR by Killian Brennan on behalf of the Authors (08 Aug 2025)  Manuscript 

Journal article(s) based on this preprint

19 Sep 2025
Saharan dust linked to European hail events
Killian P. Brennan and Lena Wilhelm
Atmos. Chem. Phys., 25, 10823–10836, https://doi.org/10.5194/acp-25-10823-2025,https://doi.org/10.5194/acp-25-10823-2025, 2025
Short summary
Killian P. Brennan and Lena Wilhelm
Killian P. Brennan and Lena Wilhelm

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Latest update: 19 Sep 2025
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Short summary
In this study, we discovered that natural dust carried into Europe significantly increases the likelihood of hailstorms. By analyzing dust data, weather records, and hail reports, we found that moderate dust levels lead to more frequent hail, while very high or low dust amounts reduce it. Adding dust information into statistical models improved forecasting skills. We aimed to understand how dust affects hailstorms.
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