气候变化领域集成服务门户(CCPortal): Uncertainties in eddy covariance air-sea CO2 flux measurements and implications for gas transfer velocity parameterisations

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DOI	10.5194/acp-21-8089-2021
	Uncertainties in eddy covariance air-sea CO2 flux measurements and implications for gas transfer velocity parameterisations
	Dong Y.; Yang M.; Bakker D.C.E.; Kitidis V.; Bell T.G.
发表日期	2021
ISSN	1680-7316
起始页码	8089
结束页码	8110
卷号	21 期号:10
英文摘要	Air sea carbon dioxide (CO2) flux is often indirectly estimated by the bulk method using the air sea difference in CO2 fugacity (1fCO2) and a parameterisation of the gas transfer velocity (K). Direct flux measurements by eddy covariance (EC) provide an independent reference for bulk flux estimates and are often used to study processes that drive K. However, inherent uncertainties in EC air sea CO2 flux measurements from ships have not been well quantified and may confound analyses of K. This paper evaluates the uncertainties in EC CO2 fluxes from four cruises. Fluxes were measured with two state-of-the-art closed-path CO2 analysers on two ships. The mean bias in the EC CO2 flux is low, but the random error is relatively large over short timescales. The uncertainty (1 standard deviation) in hourly averaged EC air sea CO2 fluxes (cruise mean) ranges from 1.4 to 3.2 mmolm2 d1. This corresponds to a relative uncertainty of 20% during two Arctic cruises that observed large CO2 flux magnitude. The relative uncertainty was greater (50 %) when the CO2 flux magnitude was small during two Atlantic cruises. Random uncertainty in the EC CO2 flux is mostly caused by sampling error. Instrument noise is relatively unimportant. Random uncertainty in EC CO2 fluxes can be reduced by averaging for longer. However, averaging for too long will result in the inclusion of more natural variability. Auto-covariance analysis of CO2 fluxes suggests that the optimal timescale for averaging EC CO2 flux measurements ranges from 1 to 3 h, which increases the mean signal-to-noise ratio of the four cruises to higher than 3. Applying an appropriate averaging timescale and suitable 1fCO2 threshold (20 uatm) to EC flux data enables an optimal analysis of K. © 2021 BMJ Publishing Group. All rights reserved.
语种	英语
scopus关键词	air-sea interaction; carbon dioxide; carbon flux; eddy covariance; flux measurement; gas exchange; parameterization; uncertainty analysis; velocity
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/246857
作者单位	Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom; Plymouth Marine Laboratory, Prospect Place, Plymouth, United Kingdom
推荐引用方式 GB/T 7714	Dong Y.,Yang M.,Bakker D.C.E.,et al. Uncertainties in eddy covariance air-sea CO2 flux measurements and implications for gas transfer velocity parameterisations[J],2021,21(10).
APA	Dong Y.,Yang M.,Bakker D.C.E.,Kitidis V.,&Bell T.G..(2021).Uncertainties in eddy covariance air-sea CO2 flux measurements and implications for gas transfer velocity parameterisations.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(10).
MLA	Dong Y.,et al."Uncertainties in eddy covariance air-sea CO2 flux measurements and implications for gas transfer velocity parameterisations".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.10(2021).