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 – Volume II

Pavla Dagsson-Waldhauserova^1,2*Outi Meinander³

• ¹Agricultural University of Iceland, Borgarnes, Iceland
• ²Ceska zemedelska univerzita v Praze, Prague, Czechia
• ³Ilmatieteen Laitos, Helsinki, Finland

In-situ aerosol measurements near local sources of particulates (dust, BC, ash from volcanic eruptions and biomass burning, pollen, etc.) in the Arctic, at high latitudes, and at high altitudes are critically needed to raise awareness of air pollution and extreme events, including dust storms, snow-dust storms, volcanic ash resuspension, and biomass burning plumes (Meinander et al., 2022). There is a lack of in-situ data to validate models and satellite products. For example, global forecast models are efficient in capturing long-range transport of dust storms and biomass burning plumes to the Arctic from the lower latitudes, but only few of them can capture the local dust and biomass burning plumes, often due to given low resolution, missing the important sources (Cvetkovic et al., 2022; Böö et al., 2023; Varga et al., 2023). Additionally, an interaction of the dust with infrared radiation in the spectral range within 15 and 100 µm is poorly understood and captured in the regional and global models although about half of thermal radiation is re-emitted by the Earth and atmosphere within this spectral range and is highly relevant for high latitudes (Di Biagio et al., 2025). Arctic haze, known as a phenomenon of impaired air quality of anthropogenic origin located far from the Arctic, consists of large quantities of super-micron aerosols dominated by mineral dust and, in turn, resulting in high ice-nucleating particle concentrations (Raif et al., 2024). In this Research Topic, the main objective was to obtain observational-and model-based investigations on all aspects of the interactions between atmospheric processes and snow and ice, emphasizing the role of aerosols and Light Absorbing Particles (LAP) in Arctic amplification and climate change. New studies of interest provide valuable insights and evidence on the role of LAP in affecting snow albedo and melt rates, the optical properties of high-latitude dust and volcanic ash, aerosol optical depth and cloud parameters, as well as processes in the near-surface boundary layer over patchy snow. What did we not know before this Research Topic, and what new knowledge has been gained? The main findings of the four papers, including 27 authors, published in this Research Topic include: New evidence is provided that Light Absorbing Particles (LAP) decrease snow albedo in shortwave spectra and change snow melt rate based on in-situ measurements including snow pits. Svensson et al. (2024) explained albedo decay at the end of the snow season to the initial amount and type of LAP deposited onto the snowpack during the winter. Snow cover season length was three days shorter for the LAP doped snow. Dirty snow had also higher temperatures in the subsurface snow layers than natural clean snow. Optical properties were investigated for high latitude dust and volcanic ash to understand their albedo properties and potential climate impacts when deposited as LAP. Koivusalo et al. (2024) revealed the impacts of particle size and moisture on their optical properties. The albedo of dry volcanic dust on the visible spectrum depending on the particle size is 0.03, similar to that of Black Carbon and lower than volcanic ash. The albedo decreases with increasing particle size. Wet dust reduces its albedo by 66% compared to dry sample, showing the importance of interaction of deposited dust and snow/soil moisture. On snow or ice, dust particles act usually darker than in the atmosphere. Centimeter-resolution atmospheric processes in the near-surface boundary layer over patchy snow were investigated by Haugeneder et al. (2024). Measurements across an idealized transition from bare ground to snow showed that the model underestimates vertical wind speed fluctuations. The growth of a stable internal boundary layer adjacent to the snow surface can be approximated by a power law. With low wind speeds, deeper stable layers develop, while strong wind speeds limit the growth. Even close to the surface, the buoyancy fluxes are heterogeneous and driven by terrain variations, which also induce the frequent decoupling of a thin layer adjacent to the snow surface. This Research Topic also includes the work of Yirga et al. (2024) providing findings on positive correlations between Aerosol Optical Depth and cloud fraction/water vapor, suggesting the aerosol interactions with clouds. In conclusion, additional in-situ measurements and experiments are needed to better constrain the effects of LAP on snow albedo, melt rate, and other associated processes, as well to provide data to validate and improve existing models. Particle size and moisture are important parameters for their optical properties and climate impacts, among the geo-mineralogical characteristics. Generalizing point-based and aerial measurements to three dimensions is an important step towards improving the boundary layer modeling.