American Association for Aerosol Research - Abstract Submission

AAAR 38th Annual Conference
October 5 - October 9, 2020

Virtual Conference

Abstract View


Constraints on the Importance of Mineral Dust and Proteinaceous Ice Nucleating Particles in the Canadian High Artic during the Fall of 2018 Based on Heat and Ammonium Sulfate Treatments

JINGWEI YUN, Erin Evoy, Soleil Worthy, Melody Fraser, Daniel Veber, Andrew Platt, Allan Bertram, University of British Columbia

     Abstract Number: 337
     Working Group: Aerosols, Clouds and Climate

Abstract
Ice nucleating particles (INPs) can trigger the heterogeneous freezing of cloud droplets at warm temperatures. Constraints on the concentration and composition of INPs are essential to predict ice formation in clouds. Despite previous INP measurements in the Arctic, our understanding of the concentrations, composition, and sources of Arctic INPs is far insufficient, especially in the fall. Here we report daily concentrations of INPs at Alert, Nunavut, a ground site in the Canadian High Arctic, during the fall of 2018 (from October to November). The contributions of mineral dust and proteinaceous particles to the total INP population were evaluated by testing the responses of INP concentrations for the samples to heat and ammonium treatments. Possible source locations of the effective INPs were investigated by combining the results for the surface coverage type in the Arctic, correlations of INP concentrations with concentrations of tracer chemical species, and simulations with a Lagrangian particle dispersion model. The results show that the INP concentrations of the samples collected in October were higher than the INP concentrations of the samples collected in November. Combining our results with previous INP measurements at Alert, a seasonal trend was observed, with an increase of the INP concentrations at Alert from spring to summer and then a decrease from summer to winter. For the samples collected in October, at T>-21 °C 60 % to 90 % of the total INPs was proteinaceous. At T-19 °C 30 % to 85 % of the total INPs was proteinaceous. At T3- suggest that South China and California are the possible sources of INPs through long range transport.