This title appears in the Scientific Report :
2014
Please use the identifier:
http://dx.doi.org/10.5194/bgd-11-11943-2014 in citations.
Please use the identifier: http://hdl.handle.net/2128/8273 in citations.
Uncertainty analysis of eddy covariance CO$_{2}$ flux measurements for different EC tower distances using an extended two-tower approach
Uncertainty analysis of eddy covariance CO$_{2}$ flux measurements for different EC tower distances using an extended two-tower approach
The use of eddy covariance CO2 flux measurements in data assimilation and other applications requires an estimate of the random uncertainty. In previous studies, the two-tower approach has yielded robust uncertainty estimates, but care must be taken to meet the often competing requirements of statis...
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Personal Name(s): | Post, H. (Corresponding Author) |
---|---|
Hendricks-Franssen, Harrie-Jan / Graf, Alexander / Schmidt, M. / Vereecken, H. | |
Contributing Institute: |
Agrosphäre; IBG-3 |
Published in: | Biogeosciences discussions, 11 (2014) 8, S. 11943 - 11983 |
Imprint: |
Katlenburg-Lindau [u.a.]
Copernicus
2014
|
DOI: |
10.5194/bgd-11-11943-2014 |
Document Type: |
Journal Article |
Research Program: |
Terrestrial Systems: From Observation to Prediction Modelling and Monitoring Terrestrial Systems: Methods and Technologies |
Link: |
OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/8273 in citations.
The use of eddy covariance CO2 flux measurements in data assimilation and other applications requires an estimate of the random uncertainty. In previous studies, the two-tower approach has yielded robust uncertainty estimates, but care must be taken to meet the often competing requirements of statistical independence (non-overlapping footprints) and ecosystem homogeneity when choosing an appropriate tower distance. The role of the tower distance was investigated with help of a roving station separated between 8 m and 34 km from a permanent EC grassland station. Random uncertainty was estimated for five separation distances with an extended two-tower approach which removed systematic differences of CO2 fluxes measured at two EC towers. This analysis was made for a dataset where (i) only similar weather conditions at the two sites were included and (ii) an unfiltered one. The extended approach, applied to weather-filtered data for separation distances of 95 m and 173 m gave uncertainty estimates in best correspondence with the independent reference method The introduced correction for systematic flux differences considerably reduced the overestimation of the two-tower based uncertainty of net CO2 flux measurements, e.g. caused by different environmental conditions at both EC towers. It is concluded that the extension of the two-tower approach can help to receive more reliable uncertainty estimates because systematic differences of measured CO2 fluxes which are not part of random error are filtered out. |