气候变化领域集成服务门户(CCPortal): Ice nucleation ability of ammonium sulfate aerosol particles internally mixed with secondary organics

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DOI	10.5194/acp-21-10779-2021
	Ice nucleation ability of ammonium sulfate aerosol particles internally mixed with secondary organics
	Bertozzi B.; Wagner R.; Song J.; Höhler K.; Pfeifer J.; Saathoff H.; Leisner T.; Möhler O.
发表日期	2021
ISSN	1680-7316
起始页码	10779
结束页码	10798
卷号	21 期号:13
英文摘要	The abundance of aerosol particles and their ability to catalyze ice nucleation are key parameters to correctly understand and describe the aerosol indirect effect on the climate. Cirrus clouds strongly influence the Earth's radiative budget, but their effect is highly sensitive to their formation mechanism, which is still poorly understood. Sulfate and organics are among the most abundant aerosol components in the troposphere and have also been found in cirrus ice crystal residuals. Most of the studies on ice nucleation at cirrus cloud conditions looked at either purely inorganic or purely organic particles. However, particles in the atmosphere are mostly found as internal mixtures, the ice nucleation ability of which is not yet fully characterized. In this study, we investigated the ice nucleation ability of internally mixed particles composed of crystalline ammonium sulfate (AS) and secondary organic material (SOM) at temperatures between -50 and -65 C. The SOM was generated from the ozonolysis of α-pinene. The experiments were conducted in a large cloud chamber, which also allowed us to simulate various aging processes that the particles may experience during their transport in the atmosphere, like cloud cycling and redistribution of the organic matter. We found that the ice nucleation ability of the mixed AS/SOM particles is strongly dependent on the particle morphology. Small organic mass fractions of 5wt%-8wt% condensed on the surface of AS crystals are sufficient to completely suppress the ice nucleation ability of the inorganic component, suggesting that the organic coating is evenly distributed on the surface of the seed particles. In this case, the ice nucleation onset increased from a saturation ratio with respect to ice Sice1/41.30 for the pure AS crystals to ≥1.45 for the SOM-coated AS crystals. However, if such SOM-coated AS crystals are subjected to the mentioned aging processes, they show an improved ice nucleation ability with the ice nucleation onset at Sice1/41.35. We suggest that the aging processes change the particle morphology. The organic matter might redistribute on the surface to form a partially engulfed structure, where the ice-nucleation-active sites of the AS crystals are no longer completely masked by the organic coating, or the morphology of the organic coating layer might transform from a compact to a porous structure. Our results underline the complexity in representing the ice nucleation ability of internally mixed particles in cloud models. They also demonstrate the need to further investigate the impact of atmospheric aging and cloud processing on the morphology and related ice nucleation ability of internally mixed particles. © Copyright:
语种	英语
scopus关键词	aerosol; aerosol composition; ammonium sulfate; catalysis; cirrus; cloud condensation nucleus; formation mechanism; radiation budget; saturation
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/246725
作者单位	Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany; CERN, Geneva, 1211, Switzerland
推荐引用方式 GB/T 7714	Bertozzi B.,Wagner R.,Song J.,et al. Ice nucleation ability of ammonium sulfate aerosol particles internally mixed with secondary organics[J],2021,21(13).
APA	Bertozzi B..,Wagner R..,Song J..,Höhler K..,Pfeifer J..,...&Möhler O..(2021).Ice nucleation ability of ammonium sulfate aerosol particles internally mixed with secondary organics.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(13).
MLA	Bertozzi B.,et al."Ice nucleation ability of ammonium sulfate aerosol particles internally mixed with secondary organics".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.13(2021).