气候变化领域集成服务门户(CCPortal): High homogeneous freezing onsets of sulfuric acid aerosol at cirrus temperatures

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DOI	10.5194/acp-21-14403-2021
	High homogeneous freezing onsets of sulfuric acid aerosol at cirrus temperatures
	Schneider J.; Höhler K.; Wagner R.; Saathoff H.; Schnaiter M.; Schorr T.; Steinke I.; Benz S.; Baumgartner M.; Rolf C.; Krämer M.; Leisner T.; Möhler O.
发表日期	2021
ISSN	1680-7316
起始页码	14403
结束页码	14425
卷号	21 期号:18
英文摘要	Homogeneous freezing of aqueous solution aerosol particles is an important process for cloud ice formation in the upper troposphere. There the air temperature is low, the ice supersaturation can be high and the concentration of ice-nucleating particles is too low to initiate and dominate cirrus cloud formation by heterogeneous ice nucleation processes. The most common description to quantify homogeneous freezing processes is based on the water activity criterion (WAC) as proposed by . The WAC describes the homogeneous nucleation rate coefficients only as a function of the water activity, which makes this approach well applicable in numerical models. In this study, we investigate the homogeneous freezing behavior of aqueous sulfuric acid aerosol particles by means of a comprehensive collection of laboratory-based homogeneous freezing experiments conducted at the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud simulation chamber, which were conducted as part of 17 measurement campaigns since 2007. The most recent experiments were conducted during October 2020 with special emphasis on temperatures below 200ĝ€¯K. Aqueous sulfuric acid aerosol particles of high purity were generated by particle nucleation in a gas flow composed of clean synthetic air and sulfuric acid vapor, which was added to the AIDA chamber. The resulting chamber aerosol had number concentrations from 30ĝ€¯cm-3 up to several thousand per cubic centimeter with particle diameters ranging from about 30ĝ€¯nm to 1.1ĝ€¯μm. Homogeneous freezing of the aerosol particles was measured at simulated cirrus formation conditions in a wide range of temperatures between 185 and 230ĝ€¯K with a steady increase of relative humidity during each experiment. At temperatures between about 205ĝ€¯K and about 230ĝ€¯K, the AIDA results agree well with the WAC-based predictions of homogeneous freezing onsets. At lower temperatures, however, the AIDA results show an increasing deviation from the WAC-based predictions towards higher freezing onsets. For temperatures between 185 and 205ĝ€¯K, the WAC-based ice saturation ratios for homogeneous freezing onsets increase from about 1.6 to 1.7, whereas the AIDA measurements show an increase from about 1.7 to 2.0 in the same temperature range. Based on the experimental results of our direct measurements, we suggest a new fit line to formulate the onset conditions of homogeneous freezing of sulfuric acid aerosol particles as an isoline for nucleation rate coefficients between 5×108 and 1013ĝ€¯cm-3ĝ€¯s-1. The potential significant impacts of the higher homogeneous freezing thresholds, as directly observed in the AIDA experiments under simulated cirrus formation conditions, on the model prediction of cirrus cloud occurrence and related cloud radiative effects are discussed. © Copyright:
语种	英语
scopus关键词	aerosol; air temperature; aqueous solution; cirrus; cloud radiative forcing; freezing; gas flow; sulfuric acid
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/246549
作者单位	Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany; Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, United States; Landesanstalt für Umwelt Baden-Württemberg, Karlsruhe, Germany; Institute for Atmospheric Physics, Johannes Gutenberg University, Mainz, Germany; Institute for Energy and Climate Research, IEK-7: Stratosphere, Research Center Jülich, Jülich, Germany; Deutscher Wetterdienst, Offenbach, Germany
推荐引用方式 GB/T 7714	Schneider J.,Höhler K.,Wagner R.,et al. High homogeneous freezing onsets of sulfuric acid aerosol at cirrus temperatures[J],2021,21(18).
APA	Schneider J..,Höhler K..,Wagner R..,Saathoff H..,Schnaiter M..,...&Möhler O..(2021).High homogeneous freezing onsets of sulfuric acid aerosol at cirrus temperatures.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(18).
MLA	Schneider J.,et al."High homogeneous freezing onsets of sulfuric acid aerosol at cirrus temperatures".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.18(2021).