| 21 Aug 2026
Quantifying the impact of Light Absorbing Impurities on snow properties and melting using mini-lysimeters in the Central Pyrenees
Abstract. The Pyrenees are experiencing an increasing frequency of atmospheric conditions favorable to African dust transport, while black carbon (BC) deposition is expected to decline in the coming decades. These two dominant light-absorbing impurities (LAIs) significantly alter snowpack properties by reducing snow surface albedo, accelerating melt, and disrupting mountain hydrology by modifying the surface energy balance. While the role of LAIs in enhancing snow metamorphism and melt is well recognized, quantifying their precise impact remains challenging due to the irregularity of deposition events, variability in impurity type and concentration, and the snowpack heterogeneity.
To better quantify and constrain the physical impacts of LAIs on snowpack, we implemented controlled field experiments using custom mini-lysimeters filled with natural snow, artificially doped with realistic concentrations of mineral dust (2, 5, 10 g/m2) and BC (0.1, 0.2 g/m2) and exposed to environmental conditions and sunlight for 3–4 hours in each set of experiments. Results revealed a systematic broadband albedo reduction of 0.2–0.3, accompanied by a marked decline in specific surface area (from ~10 to <4 m2/kg in dust-treated samples). Seasonal mean liquid water content increased from 3.1 % in clean snow to 6.2 % (2 g/m2 dust) and up to 10.1 % (10 g/m2 dust), with BC showing intermediate responses. However, the most striking effect was observed in meltwater production: even the lowest dust load frequently doubled melt rates relative to controls, and in several cases induced melt when control snow remained stable. Mineral dust outperformed BC in enhancing melt under comparable radiative conditions.
Overall, this study provides a simple and robust experimental framework for linking particle concentration to measurable changes in snow metamorphism and melt. Our results suggest that realistic concentrations of mineral dust, such as those frequently observed in the Pyrenees due to African dust deposition, can shorten snow duration and potentially reinforce the effects of ongoing climate warming.
Comments to the Editor and Authors
This is a breakthrough study from the Pyrenees showing the importance of mineral dust impacts on the cryosphere, based on in-situ experiments and comparisons with BC. Such studies are rather rare and crucially needed to improve the respective models. The paper shows that the estimated BC impacts on snow melt are surpassed that of by mineral dust, even at the lowest deposition rates. It also confirms the importance of the initial state of the snow during the time of the LAI deposition in enhancing melting rates. This work is a very well-written and systematic paper. I would definitely recommend this work for publication in EGUSphere after minor revisions.
Minor comments/suggestions:
L63 – ‘coarsening’ – are you referring here to ‘clumping mechanism’ due to BC or dust deposition too?
L73-74 – volcanic ash is maybe partly referred by Liu et al. (2014), but Arnalds et al. (2016) refers to volcanic dust (not fresh ash!). Consider to look at Koivusalo et al. (2024) for the differences.
Koivusalo, T., Dagsson-Waldhauserová, P., Gritsevich, M., and Peltoniemi, J., 2024. Light-absorbing capacity of volcanic dust from Iceland and Chile. Frontiers in Earth Sciences 12, 1348082
L77-84 – consider adding also Soot/Dust on Snow experiments in Lapland to the list here:
Svensson, J., Leppänen, L., Hannula, H.-R., Kontu, A., Shen, Y-c., Meinander, O., Dagsson-Waldhauserová, P., Mesceriakovas, A., Heikkinen, E., Ruppel, M., Sippula, O., Ström, J., Asmi, E., and Virkkula. A., 2024. Soot-on-snow experiment: artificial deposition of light-absorbing particles onto snow surfaces in 2018. Frontiers in Earth Sciences 12, 1358155.
Meinander O, Dagsson-Waldhauserova P, Arnalds O 2016. Icelandic volcanic dust can have a significant influence on the cryosphere in Greenland and elsewhere. Polar Research 35.
Svensson J., Virkkula A., Meinander O., Kivekäs N., Hannula H.-R., Järvinen O., Peltoniemi J.I., Gritsevich M., Heikkilä A., Kontu A., Neitola K., Brus D., Dagsson-Waldhauserova P., Anttila K., Vehkamäki M., Hienola A., de Leeuw G. & Lihavainen H. 2016: Soot-doped natural snow and its albedo — results from field experiments. Boreal Env. Res. 21: 481–503.
Peltoniemi, J. I., Gritsevich, M., Hakala, T., Dagsson-Waldhauserová, P., Arnalds, Ó., Anttila, K., Hannula, H.-R., Kivekäs, N., Lihavainen, H., Meinander, O., Svensson, J., Virkkula, A., de Leeuw, G., 2015. Soot on snow experiment: bidirectional reflectance factor measurements of contaminated snow. The Cryosphere 9, 3075-3111.
Meinander, O., Kontu, A., Virkkula, A., Arola, A., Backman, L., Dagsson-Waldhauserová, P., Järvinen, O., Manninen, T., Svensson, J., de Leeuw, G., and Leppäranta, M., 2014. Brief Communication: Light-absorbing impurities can reduce the density of melting snow. The Cryosphere 8, 991-995.
Dagsson-Waldhauserova, P. and Meinander, O., 2019. Editorial: Atmosphere—Cryosphere Interaction in the Arctic, at High Latitudes and Mountains With Focus on Transport, Deposition, and Effects of Dust, Black Carbon, and Other Aerosols. Frontiers in Earth Science 7, 337, 1-4.
Dagsson-Waldhauserova, P., Meinander, O., eds. (2020). Atmosphere – Cryosphere Interaction in the Arctic, at High Latitudes and Mountains With Focus on Transport, Deposition and Effects of Dust, Black Carbon, and Other Aerosols. Lausanne: Frontiers Media SA., 148 pp. doi: 10.3389/978-2-88963-504-7
L120 – not only in southern Europe – your region. There is also significant dust deposition in northern Europe (eg. Finland-Lapland, Iceland). See here:
Varga, G., Meinander, O., Rostási, A., Dagsson-Waldhauserova, P., Csávics, A., Gresina, F., 2023. Saharan, Aral-Caspian and Middle East dust travels to Finland (1980–2022). Environment International 180, 108243.
Varga, G., Dagsson-Waldhauserová, P., Gresina, F. and Helgadottir A., 2021. Saharan dust and giant quartz particle transport towards Iceland. Scientific Reports 11, 11891.
L158 - Remove the dot before bracket
L439-441 – Consider comparing your results on dust-BC albedo changes with experiments from Lapland as suggested above (Peltoniemi et al., 2015; Svensson et al., 2016, 2024; Meinander et al., 2014; Dagsson-Waldhauserova et al., 2015). This also leads to the lines 430-439 and 484-485 to discuss more why smaller dust loads initiate higher albedo reductions/snow melt. This was also observed in the papers above and is explained as ‘clumping mechanism’- a small amount of fine grained dust particles (see under silt) triggers fast clumping into large darker spots and reduce the albedo more than other experiment spots. This mechanism occurs during the first tens of minutes after the deposition. It is not visible at the time of deposition. This would be also good to discuss with your first 3-4 hours observations after deposition. Have you not observed such fast-darkening changes?
L494- Consider adding Reveillet et al. (2022) for other info on shifts in the melt days due to LAI in Pyrenees and Apls.
Réveillet, M., Dumont, M., Gascoin, S. et al. (2022). Black carbon and dust alter the response of mountain snow cover under climate change. Nature Communications 13, 5279.
L517-519 – Dry-deposition experiments have been already conducted – see the methods in Svensson et al. (2016, 2024).
References revisions:
Uncited References: Arimoto (2001), Prospero et al. (2002)
Missing References: Aoki et al. (2007)
Citation formatting errors:
-Copernicus Climate Service (2023) cited as European state of the climate 2023
- Marcolini (2017) should be Marcolini et al. (2017)