Roussel et al. (2025) Saharan dust impacts on the surface mass balance of Argentière Glacier (French Alps)

Identification

• Journal: ˜The œcryosphere
• Year: 2025
• Date: 2025-10-29
• Authors: Léon Roussel, Marie Dumont, Marion Réveillet, Delphine Six, Marin Kneib, Pierre Nabat, Kévin Fourteau, Diego Monteiro, Simon Gascoin, Emmanuel Thibert, Antoine Rabatel, Jean‐Emmanuel Sicart, Mylène Bonnefoy, Luc Piard, Olivier Laarman, Bruno Jourdain, Mathieu Fructus, Matthieu Vernay, Matthieu Lafaysse
• DOI: 10.5194/tc-19-5201-2025

Research Groups

• Centre d’Études de la Neige (CNRM, Météo-France/CNRS)
• Université Grenoble Alpes
• Université de Toulouse
• Institut des Géosciences de l’Environnement (IGE, CNRS/IRD/INRAE/Grenoble INP)
• Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich
• Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)
• Centre d’Etudes Spatiales de la Biosphère (CESBIO, CNRS/IRD/CNES/UT3)

Short Summary

This study quantifies the impact of Saharan dust and black carbon on the surface mass balance (SMB) of Argentière Glacier (French Alps) from 2019-2022, revealing that mineral dust significantly reduced annual SMB, particularly in 2022, with impacts up to 1.2 meters water equivalent (m w.e.) at specific locations.

Objective

• To quantify the impact of mineral dust on the surface mass balance (SMB) of an alpine glacier.

Study Configuration

• Spatial Scale: Argentière Glacier (11 km² in 2022), ranging from 2100 to 3600 m above sea level (a.s.l.). Simulations were performed on a 250 m horizontal resolution grid.
• Temporal Scale: Spin-up period from 2008 to 2018, followed by the period of interest from 2019 to 2022.

Methodology and Data

• Models used:
  • Snow model: SURFEX/ISBA-Crocus
  • Radiative Transfer Model: Two-streAm Radiative TransfEr in Snow (TARTES)
  • Regional Climate Model for LAPs: CNRM-ALADIN63
  • Atmospheric Reanalysis for meteorological data: SAFRAN
• Data sources:
  • Light-absorbing particles (LAPs) deposition fluxes (mineral dust, black carbon): CNRM-ALADIN63 regional climate model (12.5 km resolution).
  • Meteorological data: SAFRAN atmospheric reanalysis (300 m vertical resolution, bias-corrected with Automatic Weather Station (AWS) data), AWS on glacier and moraine.
  • Glacier outlines and Digital Elevation Model (DEM): Copernicus (10 m resolution).
  • Point Surface Mass Balance (SMB) measurements: GLACIOCLIM observatory.
  • Satellite images: Sentinel-2 (optical, high-resolution, multispectral, 10-20 m spatial resolution) for surface type, snowline elevation, and broadband ice albedo.
  • Distributed SMB: Pléiades (4 m resolution DEMs, 0.5 m ortho-images) for elevation change and surface velocity.

Main Results

• The glacier-wide annual SMB decrease due to mineral dust was between 0.31–0.45 m w.e. (median [Q10–Q90]) for 2019-2021, and increased to 0.63 m w.e. [0.54, 0.69] in 2022.
• Mineral dust contributed to 9.1 %–14.8 % of the total annual melt for 2019-2021, and 13.2 % [11.8, 14.7] in 2022.
• At specific locations, particularly near the end-of-summer snowline from previous years (around 3000 m a.s.l.), the dust impact reached up to 1.2 m w.e. [0.9, 1.4] in 2022.
• The impact of dust was spatially variable, with highest impacts occurring where firn layers from previous years, containing accumulated LAPs, were re-exposed.
• In 2022, the annual glacier-averaged albedo decreased by 0.03 [0.028, 0.033] due to dust, with a summer (May-September) decrease of 0.062 [0.056, 0.067].
• Sensitivity analysis showed that increasing the black carbon (BC) scavenging efficiency from 0.2 to 1.0 doubled the dust impact from 0.63 to 1.3 m w.e. in 2022, highlighting significant uncertainties related to LAP scavenging.

Contributions

• This study provides the first quantification of the distributed impact of mineral dust on the SMB of an entire alpine glacier (Argentière Glacier) using a physically-based snow model with explicit representation of light-absorbing particles.
• It demonstrates that the impact of LAPs on glacier SMB is not solely dependent on recent depositions but also on the re-exposure of contaminated firn layers from previous years, necessitating long-term memory in glacier models.
• The research highlights the significant spatial variability of dust impact across the glacier, with peak effects near the end-of-summer snowline.
• It identifies critical uncertainties, particularly regarding black carbon scavenging efficiency and dust mass absorption efficiency, as major modulators of the quantified dust impact, guiding future research directions.
• The transferable simulation setup paves the way for comprehensive regional assessments of LAP impacts on glaciers in monitored areas.

Funding

• European Research Council, Horizon Europe (grant no. 9495516, IVORI)
• Swiss National Science Foundation (SNSF) under the Postdoc Mobility program (grant agreement P500PN-210739, CAIRN)
• ANR SAUSSURE (ANR-18-CE01-0015-01 Sliding of glAciers and sUbglacial water pressure)

Citation

@article{Roussel2025Saharan,
  author = {Roussel, Léon and Dumont, Marie and Réveillet, Marion and Six, Delphine and Kneib, Marin and Nabat, Pierre and Fourteau, Kévin and Monteiro, Diego and Gascoin, Simon and Thibert, Emmanuel and Rabatel, Antoine and Sicart, Jean‐Emmanuel and Bonnefoy, Mylène and Piard, Luc and Laarman, Olivier and Jourdain, Bruno and Fructus, Mathieu and Vernay, Matthieu and Lafaysse, Matthieu},
  title = {Saharan dust impacts on the surface mass balance of Argentière Glacier (French Alps)},
  journal = {˜The œcryosphere},
  year = {2025},
  doi = {10.5194/tc-19-5201-2025},
  url = {https://doi.org/10.5194/tc-19-5201-2025}
}