Interfacial phenomena in snow from its formation to accumulation and shedding

Diverse and high pollution of microplastics in seasonal snow across Northeastern China

Snow scavenging is recognized as one of the major sinks for atmospheric microplastics (MPs). However, little is known about the properties of MPs in large-scale surface snow. Using Nile Red staining and micro-Fourier transform infrared spectroscopy, we identified the shapes, sizes, and polymer components of MPs in seasonal snow across northeastern (NE) China, a major industrial area. The average concentration of MPs was (4.52 ± 3.05) × 104 MPs L-1, and the highest contamination (6.65 ± 3.89) × 104 MPs L-1 was observed in Changbai Mountains, which was the highest concentration observed in surface snow to the extent of literature. The majority of snow MPs were smaller than 50 μm and composed primarily of fragments. Ethylene vinyl acetate and polyethylene were the dominant contributors to their chemical components. Investigation with positive matrix factorization revealed that the MPs were primarily generated by debris from packaging materials, followed by industrial and construction activities. In addition, the winter atmospheric circulation over the northwestern Siberian and Mongolian plateaus likely dominated the wide-range dispersion and deposition of the MPs across NE China. These results provide a first comprehensive perspective of MPs from sources to removal associated with snow in a large geographic region.

Modelling Weather Precipitation Intensity on Surfaces in Motion with Application to Autonomous Vehicles

With advances in the development of autonomous vehicles (AVs), more attention has been paid to the effects caused by adverse weather conditions. It is well known that the performance of self-driving vehicles is reduced when they are exposed to stressors that impair visibility or cause water or snow accumulation on sensor surfaces. This paper proposes a model to quantify weather precipitation, such as rain and snow, perceived by moving vehicles based on outdoor data. The modeling covers a wide range of parameters, such as varying the wind direction and realistic particle size distributions. The model allows the calculation of precipitation intensity on inclined surfaces of different orientations and on a circular driving path. The modeling results were partially validated against direct measurements carried out using a test vehicle. The model outputs showed a strong correlation with the experimental data for both rain and snow. Mitigation strategies for heavy precipitation on vehicles can be developed, and correlations between precipitation rate and accumulation level can be traced using the presented analytical model. A dimensional analysis of the problem highlighted the critical parameters that can help the design of future experiments. The obtained results highlight the importance of the angle of the sensing surface for the perceived precipitation level. The proposed model was used to analyze optimal orientations for minimization of the precipitation flux, which can help to determine the positioning of sensors on the surface of autonomous vehicles.

Heat Transfer Characteristics of Carbon-Based Photothermal Superhydrophobic Materials with Thermal Insulation Micropores During Anti-icing/Deicing

Photothermal deicing is a noncontact, economically, efficient, and environmentally friendly melting/preventing ice method. Obtaining a cheap, easily fabricated material with high photothermal conversion and deicing efficiency is a challenge. Here, carbon-based photothermal superhydrophobic materials with thermal insulation micropores were prepared by using the salt-template. We demonstrate that the microholes array structure can enhance light absorption and hydrophobicity of the material, and the micropores structure can inhibit the heat transfer from the surface to the subcooled substrate, which synergistically greatly enhances the photothermal conversion. A heat transfer model was established to clarify the influence mechanisms of air cushion on interfacial heat transfer during the photothermal anti-icing and deicing process. The self-cleaning, flexibility, mechanical, and chemical stability tests show that the material has the potential for outdoor application. The prepared materials with high photothermal deicing efficiency provide a new way for the anti-icing and deicing of outdoor equipment.