Articles | Volume 11, issue 2
https://doi.org/10.5194/gi-11-335-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gi-11-335-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Accuracies of field CO2–H2O data from open-path eddy-covariance flux systems: assessment based on atmospheric physics and biological environment
Xinhua Zhou
Ker Research and Development, CAS Key Laboratory of Forest Ecology and
Management, Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, China
Campbell Scientific Inc., Logan, UT 84321, USA
Ker Research and Development, CAS Key Laboratory of Forest Ecology and
Management, Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, China
Qingyuan Forest CERN, National Observation and Research Station,
Liaoning Province, Shenyang 110016, China
Ker Research and Development, CAS Key Laboratory of Forest Ecology and
Management, Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, China
Beijing Servirst Technology Limited, Beijing 100085, China
Bai Yang
Campbell Scientific Inc., Logan, UT 84321, USA
Yanlei Li
Ker Research and Development, CAS Key Laboratory of Forest Ecology and
Management, Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, China
Campbell Scientific Inc., Logan, UT 84321, USA
Fengyuan Yu
Ker Research and Development, CAS Key Laboratory of Forest Ecology and
Management, Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, China
Qingyuan Forest CERN, National Observation and Research Station,
Liaoning Province, Shenyang 110016, China
Tala Awada
School of Natural Resources, University of Nebraska, Lincoln, NE
68583, USA
Jiaojun Zhu
Ker Research and Development, CAS Key Laboratory of Forest Ecology and
Management, Institute of Applied Ecology, Chinese Academy of Sciences,
Shenyang 110016, China
Qingyuan Forest CERN, National Observation and Research Station,
Liaoning Province, Shenyang 110016, China
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The vortex intake significantly reduced maintenance requirements and downtime for a closed-path eddy-covariance system compared to the original inline filter design. Vortex intake kept the sample cell windows cleaner, preserving the optical signal strength of CO2 longer. Its installation also avoided the need for an inline filter in the sample path, sustaining an acceptable sample cell differential pressure over a much longer period. There was no significant attenuation of high frequencies.
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Air temperature from sonic temperature and air moisture has been used without an exact equation. We present an exact equation of such air temperature for closed-path eddy-covariance flux measurements. Air temperature from this equation is equivalent to sonic temperature in its accuracy and frequency response. It is a choice for advanced flux topics because, with it, thermodynamic variables in the flux measurements can be temporally synchronized and spatially matched at measurement scales.
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The three-dimensional wind and sonic temperature data from a physically deformed sonic anemometer was successfully recovered by developing equations, algorithms, and related software. Using two sets of geometry data from production calibration and return re-calibration, this algorithm can recover wind with/without transducer shadow correction and sonic temperature with crosswind correction, and then obtain fluxes at quality as expected. This study is applicable as a reference for related topics.
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Rigel Kivi and Pauli Heikkinen
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Carbon dioxide is the most abundant greenhouse gas emitted due to human activities. Changes in atmospheric columns of carbon dioxide can be measured accurately using ground-based Fourier transform spectrometers, which are operating in the near-infrared spectral region. Our measurements at Sodankylä reveal a significant increase of column carbon dioxide since the start of the column measurements at Sodankylä in early 2009.
T. A. Bonin, P. B. Chilson, B. S. Zielke, P. M. Klein, and J. R. Leeman
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S. Cecchini and M. Spurio
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Short summary
Overall accuracy of CO2/H2O data from open-path eddy-covariance systems is modeled for data analysis. The model is further formulated into CO2 and H2O accuracy equations for uses. Based on atmospheric physics and bio-environment, both equations are used to evaluate accuracy of ecosystem CO2/H2O data and, as rationales, to assess field CO2/H2O zero and span procedures for the systems. The procedures are assessed for measurement improvement. An impractical H2O span while cold is found unnecessary.
Overall accuracy of CO2/H2O data from open-path eddy-covariance systems is modeled for data...