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DOI	10.5194/acp-23-2035-2023
	Impact of formulations of the homogeneous nucleation rate on ice nucleation events in cirrus
	Spichtinger, Peter; Marschalik, Patrik; Baumgartner, Manuel
发表日期	2023
ISSN	1680-7316
EISSN	1680-7324
起始页码	2035
结束页码	2060
卷号	23 期号:3 页码:26
英文摘要	Homogeneous freezing of solution droplets is an important pathway of ice formation in the tropopause region. The nucleation rate can be parameterized as a function of water activity, based on empirical fits and some assumptions on the underlying properties of super-cooled water, although a general theory is missing. It is not clear how nucleation events are influenced by the exact formulation of the nucleation rate or even their inherent uncertainty. In this study we investigate the formulation of the nucleation rate of homogeneous freezing of solution droplets (1) to link the formulation to the nucleation rate of pure water droplets, (2) to derive a robust and simple formulation of the nucleation rate, and (3) to determine the impact of variations in the formulation on nucleation events.The nucleation rate can be adjusted, and the formulation can be simplified to a threshold description. We use a state-of-the-art bulk ice microphysics model to investigate nucleation events as driven by constant cooling rates; the key variables are the final ice crystal number concentration and the maximum supersaturation during the event.The nucleation events are sensitive to the slope of the nucleation rate but only weakly affected by changes in its absolute value. This leads to the conclusion that details of the nucleation rate are less important for simulating ice nucleation in bulk models as long as the main feature of the nucleation rate (i.e. its slope) is represented sufficiently well. The weak sensitivity of the absolute values to the nucleation rate suggests that the amount of available solution droplets also does not crucially affect nucleation events. The use of only one distinct nucleation threshold function for analysis and model parameterization should be reinvestigated, since it corresponds to a very high nucleation rate value, which is not reached in many nucleation events with low vertical updrafts. In contrast, the maximum supersaturation and thus the nucleation thresholds reached during an ice nucleation event depend on the vertical updraft velocity or cooling rate. This feature might explain some high supersaturation values during nucleation events in cloud chambers and suggests a reformulation of ice nucleation schemes used in coarse models based on a purely temperature-dependent nucleation threshold.
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:000929081700001
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/273799
作者单位	Johannes Gutenberg University of Mainz; Johannes Gutenberg University of Mainz; Deutscher Wetterdienst
推荐引用方式 GB/T 7714	Spichtinger, Peter,Marschalik, Patrik,Baumgartner, Manuel. Impact of formulations of the homogeneous nucleation rate on ice nucleation events in cirrus[J],2023,23(3):26.
APA	Spichtinger, Peter,Marschalik, Patrik,&Baumgartner, Manuel.(2023).Impact of formulations of the homogeneous nucleation rate on ice nucleation events in cirrus.ATMOSPHERIC CHEMISTRY AND PHYSICS,23(3),26.
MLA	Spichtinger, Peter,et al."Impact of formulations of the homogeneous nucleation rate on ice nucleation events in cirrus".ATMOSPHERIC CHEMISTRY AND PHYSICS 23.3(2023):26.