Chemical Composition and Mixing State of Wintertime Aerosol from the European Arctic Site of Ny-Ålesund
ZHENLI LAI, Zezhen Cheng, Nurun Nahar Lata, Mauro Mazzola, Stefania Gilardoni, Swarup China, Pacific Northwest National Laboratory
Abstract Number: 227
Working Group: Aerosol Chemistry
Abstract
The Arctic is experiencing unprecedented transformations due to global climate shifts. With climate change accelerating at an alarming pace in this region, the interplay between aerosols and its distinctive environmental conditions holds significant consequences for both regional and global climate systems. However, direct observations of the chemical composition of individual Arctic aerosols are scarce. This study addresses this gap by offering a comprehensive characterization of aerosol particles collected at Gruvebadet site in the European Arctic during the winter months of November to December in 2020. Employing a hybrid methodology combining k-means clustering and rule-based classification, we analyzed a total of 33,448 particles and identified six distinct particle classes based on size-resolved chemical composition data obtained through micro-spectroscopy analysis. Sea spray aerosols (SSA) emerged as the dominant class in 8 out of 9 samples, comprising 81.5% of the total aerosol population. Following closely were carbonaceous particles (16.6%), with their sources likely attributed to long-range transport. Dust particles, primarily composed of aluminosilicates, were present in all samples, often mixing with SSA in varying mixing states, accounting for 5.23% of total particle population. The prevalence of SSA/dust mixtures underscores their importance as sources of cloud condensation nuclei and ice nuclei in the Arctic atmosphere. Furthermore, we examined the relative contributions of local emissions and long-range transport to Arctic aerosol composition and size distribution through case studies of different transport pattern. Moreover, it has been observed that the aging mechanism of sea spray aerosols (SSA) is significantly influenced by cloud processing during long-range transport. Aged SSA particles exhibit an enrichment in sulfur content when their air-mass history indicates potential cloud processing. This study offers new insights into the complex mixing states and compositions of diverse high arctic aerosol particles observed at a regional scale during the Arctic winter of 2020. Our findings illuminate the intricate composition and mixing states of aerosol particles, with implications for understanding potential dominant sources of ice nucleating particles (INP) in the Arctic region during winter.