气候变化领域集成服务门户(CCPortal): Supersaturation, buoyancy, and deep convection dynamics

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DOI	10.5194/acp-21-13997-2021
	Supersaturation, buoyancy, and deep convection dynamics
	Grabowski W.W.; Morrison H.
发表日期	2021
ISSN	1680-7316
起始页码	13997
结束页码	14018
卷号	21 期号:18
英文摘要	Motivated by recent discussions concerning differences of convective dynamics in polluted and pristine environments, the so-called convective invigoration in particular, this paper provides an analysis of factors affecting convective updraft buoyancy, such as the in-cloud supersaturation, condensate and precipitation loading, and entrainment. We use the deep convective period from simulations of daytime convection development over land discussed in our previous publications. An entraining parcel framework is used in the theoretical analysis. We show that for the specific case considered here, finite (positive) supersaturation noticeably reduces pseudo-adiabatic parcel buoyancy and cumulative convective available potential energy (cCAPE) in the lower troposphere. This comes from keeping a small fraction of the water vapor in a supersaturated state and thus reducing the latent heating. Such a lower-tropospheric impact is comparable to the effects of condensate loading and entrainment in the idealized parcel framework. For the entire tropospheric depth, loading and entrainment have a much more significant impact on the total CAPE. For the cloud model results, we compare ensemble simulations applying either a bulk microphysics scheme with saturation adjustment or a more comprehensive double-moment scheme with supersaturation prediction. We compare deep convective updraft velocities, buoyancies, and supersaturations from all ensembles. In agreement with the parcel analysis, the saturation-adjustment scheme provides noticeably stronger updrafts in the lower troposphere. For the simulations predicting supersaturation, there are small differences between pristine and polluted conditions below the freezing level that are difficult to explain by standard analysis of the in-cloud buoyancy components. By applying the piggybacking technique, we show that the lower-tropospheric buoyancy differences between pristine and polluted simulations come from a combination of temperature (i.e., latent heating) and condensate loading differences that work together to make polluted buoyancies and updraft velocities slightly larger when compared to their pristine analogues. Overall, the effects are rather small and contradict previous claims of a significant invigoration of deep convection in polluted environments. © Author(s) 2021.
语种	英语
scopus关键词	buoyancy; condensate; convection; ensemble forecasting; entrainment; supersaturation; troposphere; water vapor
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/246570
作者单位	Mesoscale and Microscale Meteorology Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, United States
推荐引用方式 GB/T 7714	Grabowski W.W.,Morrison H.. Supersaturation, buoyancy, and deep convection dynamics[J],2021,21(18).
APA	Grabowski W.W.,&Morrison H..(2021).Supersaturation, buoyancy, and deep convection dynamics.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(18).
MLA	Grabowski W.W.,et al."Supersaturation, buoyancy, and deep convection dynamics".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.18(2021).