气候变化领域集成服务门户(CCPortal): Unravelling the microphysics of polar mesospheric cloud formation

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DOI	10.5194/acp-19-2871-2019
	Unravelling the microphysics of polar mesospheric cloud formation
	Duft D.; Nachbar M.; Leisner T.
发表日期	2019
ISSN	16807316
起始页码	2871
结束页码	2879
卷号	19 期号:5
英文摘要	Polar mesospheric clouds are the highest water ice clouds occurring in the terrestrial atmosphere. They form in the polar summer mesopause, the coldest region in the atmosphere. It has long been assumed that these clouds form by heterogeneous nucleation on meteoric smoke particles which are the remnants of material ablated from meteoroids in the upper atmosphere. However, until now little was known about the properties of these nanometre-sized particles and application of the classical theory for heterogeneous ice nucleation was impacted by large uncertainties. In this work, we performed laboratory measurements on the heterogeneous ice formation process at mesopause conditions on small (r = 1 to 3 nm) iron silicate nanoparticles serving as meteoric smoke analogues. We observe that ice growth on these particles sets in for saturation ratios with respect to hexagonal ice below Sh = 50, a value that is commonly exceeded during the polar mesospheric cloud season, affirming meteoric smoke particles as likely nuclei for heterogeneous ice formation in mesospheric clouds. We present a simple ice-activation model based on the Kelvin-Thomson equation that takes into account the water coverage of iron silicates of various compositions. The activation model reproduces the experimental data very well using bulk properties of compact amorphous solid water. This is in line with the finding from our previous study that ice formation on iron silicate nanoparticles occurs by condensation of amorphous solid water rather than by nucleation of crystalline ice at mesopause conditions. Using the activation model, we also show that for iron silicate particles with dry radius larger than r = 0.6 nm the nanoparticle charge has no significant effect on the ice-activation threshold. © 2019 Author(s).
语种	英语
scopus关键词	cloud microphysics; condensation; ice crystal; iron; mesopause; nanoparticle; polar mesospheric cloud; saturation; silicate; smoke
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/144594
作者单位	Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, 76021, Germany; Institute of Environmental Physics, University of Heidelberg, Heidelberg, 69120, Germany
推荐引用方式 GB/T 7714	Duft D.,Nachbar M.,Leisner T.. Unravelling the microphysics of polar mesospheric cloud formation[J],2019,19(5).
APA	Duft D.,Nachbar M.,&Leisner T..(2019).Unravelling the microphysics of polar mesospheric cloud formation.Atmospheric Chemistry and Physics,19(5).
MLA	Duft D.,et al."Unravelling the microphysics of polar mesospheric cloud formation".Atmospheric Chemistry and Physics 19.5(2019).