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Abstract. New particle formation (NPF) is a significant source of atmosphericparticles, affecting climate and air quality. Understanding the mechanismsinvolved in urban aerosols is important to develop effective mitigationstrategies. However, NPF rates reported in the polluted boundary layer spanmore than 4 orders of magnitude, and the reasons behind this variability are the subject of intense scientific debate. Multiple atmospheric vapours have beenpostulated to participate in NPF, including sulfuric acid, ammonia, aminesand organics, but their relative roles remain unclear. We investigated NPFin the CLOUD chamber using mixtures of anthropogenic vapours that simulatepolluted boundary layer conditions. We demonstrate that NPF in pollutedenvironments is largely driven by the formation of sulfuric acid–baseclusters, stabilized by the presence of amines, high ammonia concentrationsand lower temperatures. Aromatic oxidation products, despite their extremelylow volatility, play a minor role in NPF in the chosen urban environment butcan be important for particle growth and hence for the survival of newlyformed particles. Our measurements quantitatively account for NPF in highlydiverse urban environments and explain its large observed variability. Suchquantitative information obtained under controlled laboratory conditionswill help the interpretation of future ambient observations of NPF rates inpolluted atmospheres.
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Elucidating New Particle Formation in Complex Terrain During the Winter 2022 Cold Fog Amongst Complex Terrain (CFACT) Campaign
Abstract New particle formation (NPF) is a complex atmospheric phenomenon defined by the gas‐to‐particle conversion that leads to the sudden burst and growth in aerosol particles. Although chemical mechanisms for aerosol nucleation and growth are well established, the role of physical processes, such as turbulent mixing, within the atmospheric boundary layer (ABL) is beginning to emerge with recent studies. This study, based on the observations from the 2022 CFACT (Cold Fog Amongst Complex Terrain) field study in the Heber Valley of northern Utah, demonstrates an interconnection between turbulence and the occurrence of NPF. Using a spatially distributed boundary layer instrumentation, a novel feature of CFACT, three case studies depict unique boundary layer conditions that modulate the development of NPF characterized by sustained turbulence and weak intermittent turbulence. Quantitative analysis using in situ measurements and derived variables demonstrate that periods of weak intermittent turbulence hinder particle growth, whereas sustained turbulence helps modulate NPF. These findings provide new insights into the physical drivers of NPF, underscoring the role of turbulence in impacting particle formation with the ABL.
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- Award ID(s):
- 2049100
- PAR ID:
- 10593347
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 130
- Issue:
- 8
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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