气候变化领域集成服务门户(CCPortal): Nonequilibrium Fractionation During Ice Cloud Formation in iCAM5: Evaluating the Common Parameterization of Supersaturation as a Linear Function of Temperature

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DOI	10.1029/2019MS001764
	Nonequilibrium Fractionation During Ice Cloud Formation in iCAM5: Evaluating the Common Parameterization of Supersaturation as a Linear Function of Temperature
	Dütsch M.; Blossey P.N.; Steig E.J.; Nusbaumer J.M.
发表日期	2019
ISSN	19422466
起始页码	3777
结束页码	3793
卷号	11 期号:11
英文摘要	Supersaturation with respect to ice determines the strength of nonequilibrium fractionation during vapor deposition onto ice or snow and therefore influences the water isotopic composition of vapor and precipitation in cold environments. Historically, most general circulation models formed clouds through saturation adjustment and therefore prevented supersaturation. To match the observed isotopic content, especially the deuterium excess, of snow in polar regions, the saturation ratio with respect to ice (Si) was parameterized, usually by assuming a linear dependence of Si on temperature. The Community Atmosphere Model Version 5 (CAM5) no longer applies saturation adjustment for the ice phase and thus allows ice supersaturation. Here, we adapt the isotope-enabled version of CAM5 to compute nonequilibrium fractionation in ice and mixed-phase clouds based on Si from the CAM5 microphysics and use it to evaluate the common parameterization of Si. Our results show a wide range of Si predicted by the CAM5 microphysics and reflected in the simulated deuterium excess of Antarctic precipitation; this is overly simplified by the linear parameterization. Nevertheless, a linear function, when properly tuned, can reproduce the average observed relationship between δD and deuterium excess reasonably well. However, only the model-predicted Si can capture changes in microphysical conditions under different climate states that are not due to changes in temperature. Furthermore, parametric sensitivity tests show that with the model-predicted Si, water isotopes are more closely tied to the model microphysics and can therefore constrain uncertain microphysical parameters. ©2019. The Authors.
英文关键词	Antarctica; deuterium excess; ice clouds; stable water isotopes; supersaturation
语种	英语
scopus关键词	Climate models; Clouds; Deuterium; Function evaluation; Parameterization; Snow; Supersaturation; Uncertainty analysis; Antarctica; Community atmosphere model; Deuterium excess; General circulation model; Ice clouds; Linear parameterizations; Microphysical parameters; Stable water isotopes; Ice; air temperature; cloud microphysics; deuterium; fractionation; general circulation model; ice; isotopic composition; parameterization; precipitation (climatology); stable isotope; supersaturation
来源期刊	Journal of Advances in Modeling Earth Systems
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/156824
作者单位	Department of Earth and Space Sciences, University of Washington, Seattle, WA, United States; Department of Atmospheric Sciences, University of Washington, Seattle, WA, United States; National Center for Atmospheric Research, Boulder, CO, United States
推荐引用方式 GB/T 7714	Dütsch M.,Blossey P.N.,Steig E.J.,et al. Nonequilibrium Fractionation During Ice Cloud Formation in iCAM5: Evaluating the Common Parameterization of Supersaturation as a Linear Function of Temperature[J],2019,11(11).
APA	Dütsch M.,Blossey P.N.,Steig E.J.,&Nusbaumer J.M..(2019).Nonequilibrium Fractionation During Ice Cloud Formation in iCAM5: Evaluating the Common Parameterization of Supersaturation as a Linear Function of Temperature.Journal of Advances in Modeling Earth Systems,11(11).
MLA	Dütsch M.,et al."Nonequilibrium Fractionation During Ice Cloud Formation in iCAM5: Evaluating the Common Parameterization of Supersaturation as a Linear Function of Temperature".Journal of Advances in Modeling Earth Systems 11.11(2019).