DOI: 10.1002/jgrd.50763
论文题名: Effect of imprecise lag time and high-frequency attenuation on surface-atmosphere exchange fluxes determined with the relaxed eddy accumulation method
作者: Moravek A. ; Trebs I. ; Foken T.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 17 起始页码: 10210
结束页码: 10224
语种: 英语
英文关键词: air-surface exchange
; high frequency attenuation
; lag time
; relaxed eddy accumulation
; tube effects
Scopus关键词: Carbon dioxide
; Errors
; Inlet flow
; Uncertainty analysis
; Air-surface exchanges
; Concentration fluctuation
; Cross correlation methods
; High frequency attenuation
; Lag-time
; Measurement uncertainty
; Relaxed Eddy accumulation
; Relaxed eddy accumulations
; Tubes (components)
; carbon dioxide
; eddy covariance
; flux measurement
; frequency analysis
; ozone
; temperature effect
; uncertainty analysis
; volume
; wind velocity
英文摘要: Relaxed eddy accumulation (REA) systems that employ one single long inlet tube are prone to measurement uncertainties caused by (a) an imprecisely determined lag time between the change of sign in the vertical wind velocity and the switching of the splitter valves and (b) attenuation of high-frequency concentration fluctuations in the tube flow. However, there is currently no commonly applied procedure to address these uncertainties. In this study, we first evaluated the lag time error of the volume flow, mass flow, and cross-correlation method (online and offline) and experimentally determined the magnitude of high-frequency attenuation for a 21.5 m long inlet tube of an operating REA system. In a second step, we simulated the impact for different artificial lag time errors and low-pass filter strengths on the REA concentration differences and, thus, on the REA flux, using high-frequency time series of temperature, O3 , CO2 , and H2 O. The reduction of scalar fluxes was mainly correlated with increasing switching frequencies and ranged for typical lag time errors of the investigated REA system between <5% and 50%, whereas the flux loss due to high-frequency attenuation was between <5% and 30%. The results were very similar for all scalar quantities. Based on our results, we derived empirical correction functions for both imprecise lag times and high-frequency attenuation, discuss their potential application to correct fluxes measured with other REA systems, and give a general procedure to address the uncertainties in future REA setups. Key Points Imprecise lag time and tube effects introduce uncertainties to REA fluxesUncertainties depend on turbulence, setup and scalar quantityCorrection methods are discussed ©2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63333
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Biogeochemistry Department, Max Planck Institute for Chemistry, PO Box 3060, 55020 Mainz, Germany; Department of Micrometeorology, University of Bayreuth, Bayreuth, Germany; Bayreuth Center of Ecology and Environmental Research, University of Bayreuth, Bayreuth, Germany
Recommended Citation:
Moravek A.,Trebs I.,Foken T.. Effect of imprecise lag time and high-frequency attenuation on surface-atmosphere exchange fluxes determined with the relaxed eddy accumulation method[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(17)