气候变化领域集成服务门户(CCPortal): Mechanistic links between underestimated CO2 fluxes and non-closure of the surface energy balance in a semi-arid sagebrush ecosystem

CCPortal

DOI	10.1088/1748-9326/ab082d
	Mechanistic links between underestimated CO2 fluxes and non-closure of the surface energy balance in a semi-arid sagebrush ecosystem
	Gao Z.; Liu H.; Missik J.E.C.; Yao J.; Huang M.; Chen X.; Arntzen E.; McFarland D.P.
发表日期	2019
ISSN	17489318
卷号	14 期号:4
英文摘要	The surface energy balance non-closure problem in eddy covariance (EC) studies has been largely attributed to the influence of large-scale turbulent eddies (hereafter large eddies) on latent and sensible heat fluxes. However, how such large eddies concurrently affect CO2 fluxes remains less studied and mechanistic links between the energy balance non-closure and CO2 fluxes are not well understood. Here, using turbulence data collected from an EC tower over a sagebrush ecosystem during two growing seasons, we decomposed the turbulence data into small and large eddies at a cutoff frequency and analyzed their contributions to the fluxes. We found that the magnitude of CO2 fluxes decreased concurrently with decreased sensible and latent heat fluxes (and thus increased energy balance non-closure), primarily caused by large turbulent eddies. The contributions of such large eddies to fluxes are dependent not only upon their magnitudes of vertical velocity (w) and scalars (i.e. temperature, water vapor density, and CO2 concentration), but also upon the phase differences between the large eddies of w and scalars via their covariances. Enlarged phase differences between large eddies of w and these scalars simultaneously led to reductions in the magnitudes of both CO2 and heat fluxes, linking the lower CO2 fluxes to energy balance non-closure. Such increased phase differences of large eddies were caused by changes in the structures of large eddies from unstable to near neutral conditions. Given widespread observations in non-closure in the flux community, the processes identified here may bias CO2 fluxes at many sites and cause upscaled regional and global budgets to be underestimated. More studies are needed to investigate how landscape heterogeneity influences CO2 fluxes through the influence of associated large eddies on flux exchange. © 2019 The Author(s). Published by IOP Publishing Ltd.
英文关键词	CO2 flux; eddy covariance method; ensemble empirical mode decomposition; sensible and latent heat fluxes; surface energy balance closure
语种	英语
scopus关键词	Budget control; Cutoff frequency; Ecosystems; Energy balance; Heat flux; Interfacial energy; Latent heat; Turbulence; CO2 fluxes; Eddy covariance method; Ensemble empirical mode decomposition; Landscape heterogeneities; Near-neutral conditions; Sensible and latent heat fluxes; Sensible heat flux; Vertical velocity; Carbon dioxide; carbon dioxide; carbon flux; decomposition analysis; energy balance; growing season; latent heat flux; semiarid region; sensible heat flux; terrestrial ecosystem; Artemisia tridentata
来源期刊	Environmental Research Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/154622
作者单位	Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman, WA, United States; Key Laboratory for Semi-Arid Climate Change, Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China; Pacific Northwest National Laboratory, Richland, WA 99352, United States
推荐引用方式 GB/T 7714	Gao Z.,Liu H.,Missik J.E.C.,et al. Mechanistic links between underestimated CO2 fluxes and non-closure of the surface energy balance in a semi-arid sagebrush ecosystem[J],2019,14(4).
APA	Gao Z..,Liu H..,Missik J.E.C..,Yao J..,Huang M..,...&McFarland D.P..(2019).Mechanistic links between underestimated CO2 fluxes and non-closure of the surface energy balance in a semi-arid sagebrush ecosystem.Environmental Research Letters,14(4).
MLA	Gao Z.,et al."Mechanistic links between underestimated CO2 fluxes and non-closure of the surface energy balance in a semi-arid sagebrush ecosystem".Environmental Research Letters 14.4(2019).