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Abstract. Ice-nucleating particles (INPs) initiate primary ice formation in Arctic mixed-phase clouds (MPCs), 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 MPCs 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 (NINP) during the observation season were approximately up to 3 orders of magnitude lower compared to the global average, with several samples showing degradation of NINP 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 NINP and 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 that the abundance, physicochemical properties, and potential sources of INPs in the Arctic are highly variable despite its remote location.
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Ice‐Nucleating Particles Are Emitted by Raindrop Impact
Abstract Ice‐nucleating particles (INPs) play a key role in ice formation and cloud microphysics and thus significantly impact the water cycle and the climate. However, our understanding of atmospheric INPs, particularly their sources, emissions, and spatiotemporal variability, is incomplete. While the enhancement of atmospheric INP concentrations with rainfall has been previously shown, a mechanistic understanding of the process is lacking. Here, we link detailed precipitation observations with near‐surface atmospheric INP concentrations at a semiarid grassland site in Colorado. Considering the during‐precipitation air samples, INP concentrations positively correlate with cumulative rainfall kinetic energy and amount, suggesting that INP aerosolization is induced by raindrop and hailstone impact. By additionally analyzing the INP content of precipitation water, terrestrial source samples, and heat‐treated samples, we demonstrate that local plants are the most plausible source of rain‐induced INPs during a precipitation event. Should INPs aerosolized by precipitation rise to cloud height, they could influence cloud ice fraction and initiate precipitation resulting in an aerosol‐cloud‐precipitation feedback.
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- PAR ID:
- 10600124
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 130
- Issue:
- 11
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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