气候变化领域集成服务门户(CCPortal): Continuous secondary-ice production initiated by updrafts through the melting layer in mountainous regions

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DOI	10.5194/acp-21-3855-2021
	Continuous secondary-ice production initiated by updrafts through the melting layer in mountainous regions
	Lauber A.; Henneberger J.; Mignani C.; Ramelli F.; Pasquier J.T.; Wieder J.; Hervo M.; Lohmann U.
发表日期	2021
ISSN	1680-7316
起始页码	3855
结束页码	3870
卷号	21 期号:5
英文摘要	An accurate prediction of the ice crystal number concentration in clouds is important to determine the radiation budget, the lifetime, and the precipitation formation of clouds. Secondary-ice production is thought to be responsible for the observed discrepancies between the ice crystal number concentration and the ice-nucleating particle concentration in clouds. The Hallett-Mossop process is active between-3 and-8 °C and has been implemented into several models, while all other secondary-ice processes are poorly constrained and lack a well-founded quantification. During 2 h of measurements taken on a mountain slope just above the melting layer at temperatures warmer than-3< °C, a continuously high concentration of small plates identified as secondary ice was observed. The presence of drizzle drops suggests droplet fragmentation upon freezing as the responsible secondary-ice mechanism. The constant supply of drizzle drops can be explained by a recirculation theory, suggesting that melted snowflakes, which sedimented through the melting layer, were reintroduced into the cloud as drizzle drops by orographically forced updrafts. Here we introduce a parametrization of droplet fragmentation at slightly sub-zero temperatures, where primary-ice nucleation is basically absent, and the first ice is initiated by the collision of drizzle drops with aged ice crystals sedimenting from higher altitudes. Based on previous measurements, we estimate that a droplet of 200 μm in diameter produces 18 secondary-ice crystals when it fragments upon freezing. The application of the parametrization to our measurements suggests that the actual number of splinters produced by a fragmenting droplet may be up to an order of magnitude higher. © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.
语种	英语
scopus关键词	cloud droplet; drizzle; ice crystal; melting; mountain region; nucleation; parameterization; temperature; updraft
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/247065
作者单位	Eth Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland; Department of Environmental Sciences, University of Basel, Basel, Switzerland; Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland
推荐引用方式 GB/T 7714	Lauber A.,Henneberger J.,Mignani C.,et al. Continuous secondary-ice production initiated by updrafts through the melting layer in mountainous regions[J],2021,21(5).
APA	Lauber A..,Henneberger J..,Mignani C..,Ramelli F..,Pasquier J.T..,...&Lohmann U..(2021).Continuous secondary-ice production initiated by updrafts through the melting layer in mountainous regions.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(5).
MLA	Lauber A.,et al."Continuous secondary-ice production initiated by updrafts through the melting layer in mountainous regions".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.5(2021).