Anthropogenic Dust as a Significant Source of Ice-Nucleating Particles in the Urban Environment

Anthropogenic dust is an important constituent of airborne particles in the urban environment but its ice nucleation activity remains poorly investigated. Here, we studied the sources and ice nucleating properties of size-resolved particles in the urban atmosphere under mixed-phase cloud conditions. The heat-resistant ice nucleating particles (INPs) unexpectedly contributed similar to 70% of the supermicron INPs at temperatures below -15 degrees C. A detailed chemical composition analysis of size-resolved particles revealed that these INPs were associated with anthropogenic dust, such as traffic-influenced road dust. A parameterization based on supermicron particles was developed to predict the anthropogenic dust INP concentration, given their correlations on concentration and similarity in chemical compositions. Once integrated into global models, this parameterization holds the potential to assess the contribution of anthropogenic dust to INPs on a global scale. Given the considerable presence of anthropogenic dust in the atmosphere and its significant role as INPs, we suggest it may be an important aerosol source influencing cloud microphysics and warrant further investigations. Anthropogenic dust (dust particles generated by human activities) is prevalent in the urban atmosphere, but its ice nucleation ability is poorly understood. Combining the chemical composition analysis and ice-nucleating particle (INP) measurements of urban aerosols, we found anthropogenic dust, such as traffic-influenced road dust, is an important source of atmospheric INPs. A new parameterization has been developed to predict INPs contributed by anthropogenic dust based on the number concentration of supermicron particles. Given the important role of anthropogenic dust as an INP contributor and its significant presence in the atmosphere, we propose that anthropogenic dust may play a role in influencing cloud microphysics by serving as INPs. Supermicron ice nucleating particles (INPs) contribute similar to 95.2% of the total INPs in the urban environmentAnthropogenic dust such as traffic-influenced road dust proved to be a major source of the observed heat-resistant INPsSupermicron particles are strongly correlated to anthropogenic dust INPs and can be used to predict their concentration