气候变化领域集成服务门户(CCPortal): Heavy snowfall event over the Swiss Alps: did wind shear impact secondary ice production?

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DOI	10.5194/acp-23-2345-2023
	Heavy snowfall event over the Swiss Alps: did wind shear impact secondary ice production?
	Dedekind, Zane; Grazioli, Jacopo; Austin, Philip H.; Lohmann, Ulrike
发表日期	2023
ISSN	1680-7316
EISSN	1680-7324
起始页码	2345
结束页码	2364
卷号	23 期号:4 页码:20
英文摘要	The change in wind direction and speed with height, referred to as vertical wind shear, causes enhanced turbulence in the atmosphere. As a result, there are enhanced interactions between ice particles that break up during collisions in clouds which could cause heavy snowfall. For example, intense dual-polarization Doppler signatures in conjunction with strong vertical wind shear were observed by an X-band weather radar during a wintertime high-intensity precipitation event over the Swiss Alps. An enhancement of differential phase shift (Kdp > 1 degrees km(-1)) around -15 degrees C suggested that a large population of oblate ice particles was present in the atmosphere. Here, we show that ice-graupel collisions are a likely origin of this population, probably enhanced by turbulence. We perform sensitivity simulations that include ice-graupel collisions of a cold frontal passage to investigate whether these simulations can capture the event better and whether the vertical wind shear had an impact on the secondary ice production (SIP) rate. The simulations are conducted with the Consortium for Small-scale Modeling (COSMO), at a 1 km horizontal grid spacing in the Davos region in Switzerland. The rime-splintering simulations could not reproduce the high ice crystal number concentrations, produced too large ice particles and therefore overestimated the radar reflectivity. The collisional-breakup simulations reproduced both the measured horizontal reflectivity and the ground-based observations of hydrometeor number concentration more accurately (similar to 20 L-1). During 14:30-15:45 UTC the vertical wind shear strengthened by 60 % within the region favorable for SIP. Calculation of the mutual information between the SIP rate and vertical wind shear and updraft velocity suggests that the SIP rate is best predicted by the vertical wind shear rather than the updraft velocity. The ice-graupel simulations were insensitive to the parameters in the model that control the size threshold for the conversion from ice to graupel and snow to graupel.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000936323700001
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/273244
作者单位	University of British Columbia; Swiss Federal Institutes of Technology Domain; Ecole Polytechnique Federale de Lausanne; Swiss Federal Institutes of Technology Domain; ETH Zurich
推荐引用方式 GB/T 7714	Dedekind, Zane,Grazioli, Jacopo,Austin, Philip H.,et al. Heavy snowfall event over the Swiss Alps: did wind shear impact secondary ice production?[J],2023,23(4):20.
APA	Dedekind, Zane,Grazioli, Jacopo,Austin, Philip H.,&Lohmann, Ulrike.(2023).Heavy snowfall event over the Swiss Alps: did wind shear impact secondary ice production?.ATMOSPHERIC CHEMISTRY AND PHYSICS,23(4),20.
MLA	Dedekind, Zane,et al."Heavy snowfall event over the Swiss Alps: did wind shear impact secondary ice production?".ATMOSPHERIC CHEMISTRY AND PHYSICS 23.4(2023):20.