Composition and mixing state of Arctic aerosol and cloud residual particles from long-term single-particle observations at Zeppelin Observatory, Svalbard

Abstract

Abstract. The Arctic region is sensitive to climate change and is warming faster than the global average. Aerosol particles change cloud properties by acting as cloud condensation nuclei and ice-nucleating particles, thus influencing the Arctic climate system. Therefore, understanding the aerosol particle properties in the Arctic is needed to interpret and simulate their influences on climate. In this study, we collected ambient aerosol particles using whole-air and PM10 inlets and residual particles of cloud droplets and ice crystals from Arctic low-level clouds (typically, all-liquid or mixed-phase clouds) using a counterflow virtual impactor inlet at the Zeppelin Observatory near Ny-Ålesund, Svalbard, within a time frame of 4 years. We measured the composition and mixing state of individual fine-mode particles in 239 samples using transmission electron microscopy. On the basis of their composition, the aerosol and cloud residual particles were classified as mineral dust, sea salt, K-bearing, sulfate, and carbonaceous particles. The number fraction of aerosol particles showed seasonal changes, with sulfate dominating in summer and sea salt increasing in winter. There was no measurable difference in the fractions between ambient aerosol and cloud residual particles collected at ambient temperatures above 0 ∘C. On the other hand, cloud residual samples collected at ambient temperatures below 0 ∘C had several times more sea salt and mineral dust particles and fewer sulfates than ambient aerosol samples, suggesting that sea spray and mineral dust particles may influence the formation of cloud particles in Arctic mixed-phase clouds. We also found that 43 % of mineral dust particles from cloud residual samples were mixed with sea salt, whereas only 18 % of mineral dust particles in ambient aerosol samples were mixed with sea salt. This study highlights the variety in aerosol compositions and mixing states that influence or are influenced by aerosol–cloud interactions in Arctic low-level clouds.

Effect of Long‐Range Transported Fire Aerosols on Cloud Condensation Nuclei Concentrations and Cloud Properties at High Latitudes

“…Interestingly, at Zeppelin, we observed the opposite trend for the inorganic and organic contribution: during the NF period, aerosols had a higher inorganic fraction (44%) than during the fire episode (20%) (Figure 2a). High inorganic mass fractions at Zeppelin during the clean period (NF) are likely due to the influence of marine emissions (Adachi et al., 2022). During the fire episode, the organic mass fraction increased substantially (from 66% to 80%), indicating the impact of the fire emissions and other terrestrial sources.…”

Regionally sourced bioaerosols drive high-temperature ice nucleating particles in the Arctic

“…These TEM samples were collected on 200 mesh Cu grids with a formvar carbon substrate (U1007, EM-Japan, Japan). The sampling details using the same sampler and location have been reported 76 but for fine-mode samples (<700 nm). The TEM grids were measured using a transmission electron microscope (JEM-1400, JEOL, Japan) with an energy-dispersive X-ray spectrometer (EDS; X-Max 80 mm, Oxford Instruments, Japan).…”

Contribution of fluorescent primary biological aerosol particles to low-level Arctic cloud residuals

“…For one CE in August 2020, a sample with coarse mode aerosol used for transmission electronic microscopy (TEM, for particles above 0.7 µm in aerodynamic diameter) was successfully sampled for 30 min at 1 lpm behind the CVI inlet and the particles were classified using the elemental composition described by Adachi et al (2022). On the TEM grid, three PBAP were successfully identified (among the 133 particles analyzed and representing around ≈2% of the particles collected) based on their shape and composition, confirming the presence of PBAP in the cloud residuals.…”

“…For a CE on the 22nd of August 2020, one TEM grid with identified PBAP was successfully sampled for 30 minutes behind the CVI which overlapped with the MBS sampling. Using the elemental analysis described by Adachi et al (2020Adachi et al ( , 2022, we assessed the probable nature of the aerosol in the coarse mode sampled on the grid. The TEM images (Figure 2-A,B,C) show 3 PBAP that were part of cloud residuals (out of the 133 particles analyzed from the TEM grid or around 2%).…”