Towards the development of a baseline in ground-based ice-nucleating particle properties across the world
Abstract
Atmospheric ice particles influence clouds, precipitation and climate, and often form with help from aerosol particles that serve as ice-nucleating particles (INPs). Despite the importance of INPs and ongoing efforts, little is known about their atmospheric abundance and ice nucleation efficiency, and their role in clouds and the climate system is thereby poorly constrained. Here, we present the ground-level INP properties characterized at three atmospheric observatories: continent-representative, remote marine and Alaskan Arctic sites. In particular, we will discuss the ambient INP abundance measured from 2019 to 2022 and associated baseline device data from the Atmospheric Radiation Measurement (ARM) facilities (Southern Great Plains, SGP, and Eastern North Atlantic, ENA, sites) and Barrow Atmospheric Baseline Observatory in Alaska in an effort to parameterize the baseline of ambient INPs. A combination of an automated and continuously operating expansion cooling ice chamber, the cold stage-supported offline droplet-freezing assay systems and single-particle micro-spectroscopic techniques (e.g., energy dispersive X-ray analysis) were used to elucidate the abundance and physicochemical properties (e.g., heat sensitivity etc.) of INPs at each site. Our Autumn results (Oct - Nov) show that the ground-based INP concentration (nINP(T)) measured at -25 °C varies on average from 0.4 L-1 (Alaskan Arctic) to ~19.6 L-1 (continental ARM-SGP). Likewise, the measured total aerosol concentration (naer) shows two orders of magnitude variation, ranging from 96.4 cm-3 (Alaskan Arctic) to 2,896.7 cm-3 (continental ARM-SGP). Our remote marine results from the ARM-ENA region for the same season show the moderate abundance of nINP(-25°C) (5 L-1) and naer (339 cm-3) with distinctly unique features of (1) less heat sensitivity based on our freezing assay analysis and (2) predominance of condensation-mode active INPs from our online nINP(T) monitoring as compared to the continental results. The implications of these properties will be discussed. Ultimately, to further assess the role of INPs in mixed-phase clouds and the climate system, we plan to continue investigating their source, vertical profile, seasonal variation and prediction errors.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.A45C..01H