Physicochemical Characterization and Source Apportionment of Arctic Ice Nucleating Particles Observed in Ny-Ålesund in Autumn 2019

Abstract

Abstract. Ice nucleating particles (INPs) initiate primary ice formation in Arctic mixed-phase clouds, altering cloud radiative properties and modulating precipitation. For atmospheric INPs, the complexity of their spatiotemporal variations, heterogeneous sources and evolution via intricate atmospheric interactions challenge the understanding of their impact on microphysical processes in Arctic mixed-phase clouds and induce an uncertain representation in climate models. In this work, we performed a comprehensive analysis of atmospheric aerosols at the Arctic coastal site in Ny-Ålesund (Svalbard, Norway) from October to November 2019, including their ice nucleation ability, physicochemical properties and potential sources. Overall, INP concentrations during the observation season were approximately up to three orders of magnitude lower compared to the global average, with several samples showing degradation of INP concentrations after heat treatment, implying the presence of proteinaceous INPs. Particle fluorescence was substantially associated with INP concentrations at warmer ice nucleation temperatures, indicating that in the far-reaching Arctic, aerosols of biogenic origin throughout the snow- and ice-free season may serve as important INP sources. In addition, case studies revealed the links between elevated INP concentrations to heat-lability, fluorescence, high wind speeds originating from the ocean, augmented concentration of coarse-mode particles and abundant organics. Backward trajectory analysis demonstrated a potential connection between high-latitude dust sources and high INP concentrations, while prolonged air mass history over the ice pack was identified for most scant INP cases. The combination of the above analyses demonstrates the abundance, physicochemical properties and potential sources of INPs in the Arctic are highly variable despite its remote location.

Diurnal cycle of bioaerosols is a key driver of ice nucleating particle variability for Eastern Mediterranean orographic clouds

“…Figure 5a shows that the variability pattern of ABC WIBS resembles that of INPs and the both are signi cantly correlated, except ABC WIBS exhibits a fairly constantly lower concentration level by a factor of 5. This alone suggests that biological particles may constitute 20% of the INPs, which given their unique niche properties and observed concentration (i.e., nucleating ice at warmer temperatures than any other atmospheric INPs) 53 , means that they are an important driver of glaciation processes in clouds. The considerable contribution of biological particles to the observed INPs is also supported by Fig.…”

Physicochemical characterization and source apportionment of Arctic ice-nucleating particles observed in Ny-Ålesund in autumn 2019

“…Data availability. The data presented in this study are available at https://doi.org/10.3929/ethz-b-000632439 (Li et al, 2023).…”

“…However, cases with ice crystal number concentrations limited by the available INPs have also been observed in the Arctic (Pasquier et al, 2022b). Despite the extraordinary paucity of INPs in the troposphere and that at −15 • C, approximately 1 in 10 5 to 10 6 aerosol particles can act as an INP (e.g., Kanji et al, 2017;Petters and Wright, 2015); their type, abundance, and variability can indirectly affect the climate by altering the microphysical and radiative properties of MPCs (e.g., DeMott et al, 2010;Lohmann, 2002). For instance, cloud-resolving modeling studies revealed that the liquid and ice water path (Eirund et al, 2019), atmospheric stability (Jiang et al, 2000;Harrington et al, 1999), and precipitation (Harrington and Olsson, 2001) in the Arctic MPCs respond sensitively to INP perturbations in abundance and efficiency, and the responses were dominant over altering the cloud condensation nuclei (CCN) concentrations (Solomon et al, 2018).…”