scholarly journals Comparison of ozone fluxes over grassland by gradient and eddy covariance technique

2009 ◽  
Vol 10 (3) ◽  
pp. 164-169 ◽  
Author(s):  
Jennifer B. A. Muller ◽  
Mhairi Coyle ◽  
David Fowler ◽  
Martin W. Gallagher ◽  
Eiko G. Nemitz ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Eddy Covariance Technique ◽  
Ozone Fluxes

scholarly journals Towards a standardized processing of Net Ecosystem Exchange measured with eddy covariance technique: algorithms and uncertainty estimation

2006 ◽  
Vol 3 (4) ◽  
pp. 571-583 ◽  
Author(s):  
D. Papale ◽  
M. Reichstein ◽  
M. Aubinet ◽  
E. Canfora ◽  
C. Bernhofer ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystem ◽  
Climatic Conditions ◽  
High Temporal Resolution ◽  
Eddy Covariance Technique ◽  
Forest Sites ◽  
European Database

Abstract. Eddy covariance technique to measure CO2, water and energy fluxes between biosphere and atmosphere is widely spread and used in various regional networks. Currently more than 250 eddy covariance sites are active around the world measuring carbon exchange at high temporal resolution for different biomes and climatic conditions. In this paper a new standardized set of corrections is introduced and the uncertainties associated with these corrections are assessed for eight different forest sites in Europe with a total of 12 yearly datasets. The uncertainties introduced on the two components GPP (Gross Primary Production) and TER (Terrestrial Ecosystem Respiration) are also discussed and a quantitative analysis presented. Through a factorial analysis we find that generally, uncertainties by different corrections are additive without interactions and that the heuristic u*-correction introduces the largest uncertainty. The results show that a standardized data processing is needed for an effective comparison across biomes and for underpinning inter-annual variability. The methodology presented in this paper has also been integrated in the European database of the eddy covariance measurements.

VINEYARD EVAPOTRANSPIRATION MEASUREMENT IN NON-FLAT TERRAIN CONDITIONS BY THE EDDY COVARIANCE TECHNIQUE ¿ DOURO WINE REGION, PORTUGAL

2011 ◽  
pp. 295-302 ◽  
Author(s):  
P.A. Paço ◽  
N.S. Conceição ◽  
M.I. Ferreira ◽  
A.C. Malheiro ◽  
A.A. Fernandes-Silva ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Eddy Covariance Technique ◽  
Flat Terrain ◽  
Wine Region

scholarly journals Ergodicity test of the eddy-covariance technique

2015 ◽  
Vol 15 (17) ◽  
pp. 9929-9944 ◽  
Author(s):  
J. Chen ◽  
Y. Hu ◽  
Y. Yu ◽  
S. Lü
Keyword(s):  
Eddy Covariance ◽  
Ergodic Theorem ◽  
Atmospheric Turbulence ◽  
Finite Time ◽  
Similarity Theory ◽  
Ensemble Average ◽  
Ergodic Hypothesis ◽  
Eddy Covariance Technique ◽  
Single Station ◽  
Time Average

Abstract. The ergodic hypothesis is a basic hypothesis typically invoked in atmospheric surface layer (ASL) experiments. The ergodic theorem of stationary random processes is introduced to analyse and verify the ergodicity of atmospheric turbulence measured using the eddy-covariance technique with two sets of field observational data. The results show that the ergodicity of atmospheric turbulence in atmospheric boundary layer (ABL) is relative not only to the atmospheric stratification but also to the eddy scale of atmospheric turbulence. The eddies of atmospheric turbulence, of which the scale is smaller than the scale of the ABL (i.e. the spatial scale is less than 1000 m and temporal scale is shorter than 10 min), effectively satisfy the ergodic theorems. Under these restrictions, a finite time average can be used as a substitute for the ensemble average of atmospheric turbulence, whereas eddies that are larger than ABL scale dissatisfy the mean ergodic theorem. Consequently, when a finite time average is used to substitute for the ensemble average, the eddy-covariance technique incurs large errors due to the loss of low-frequency information associated with larger eddies. A multi-station observation is compared with a single-station observation, and then the scope that satisfies the ergodic theorem is extended from scales smaller than the ABL, approximately 1000 m to scales greater than about 2000 m. Therefore, substituting the finite time average for the ensemble average of atmospheric turbulence is more faithfully approximate the actual values. Regardless of vertical velocity or temperature, the variance of eddies at different scales follows Monin–Obukhov similarity theory (MOST) better if the ergodic theorem can be satisfied; if not it deviates from MOST. The exploration of ergodicity in atmospheric turbulence is doubtlessly helpful in understanding the issues in atmospheric turbulent observations and provides a theoretical basis for overcoming related difficulties.

scholarly journals Can CO2 Turbulent Flux Be Measured by Lidar? A Preliminary Study

2011 ◽  
Vol 28 (3) ◽  
pp. 365-377 ◽  
Author(s):  
Fabien Gibert ◽  
Grady J. Koch ◽  
Jeffrey Y. Beyon ◽  
Timothy W. Hilton ◽  
Kenneth J. Davis ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Turbulent Fluxes ◽  
Time Averaging ◽  
Co2 Fluxes ◽  
Eddy Covariance Technique ◽  
Integral Scales ◽  
Vertical Profiling ◽  
In Situ Sensors ◽  
Preliminary Study

Abstract The vertical profiling of CO2 turbulent fluxes in the atmospheric boundary layer (ABL) is investigated using a coherent differential absorption lidar (CDIAL) operated nearby a tall tower in Wisconsin during June 2007. A CDIAL can perform simultaneous range-resolved CO2 DIAL and velocity measurements. The lidar eddy covariance technique is presented. The aims of the study are (i) an assessment of performance and current limitation of available CDIAL for CO2 turbulent fluxes and (ii) the derivation of instrument specifications to build a future CDIAL to perform accurate range-resolved CO2 fluxes. Experimental lidar CO2 mixing ratio and vertical velocity profiles are successfully compared with in situ sensors measurements. Time and space integral scales of turbulence in the ABL are addressed that result in limitation for time averaging and range accumulation. A first attempt to infer CO2 fluxes using an eddy covariance technique with currently available 2-μm CDIAL dataset is reported.

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