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Evaluation and optimization of ICOS atmosphere station data as part of the labeling process

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Yver-Kwok Camille, Philippon Carole, Bergamaschi Peter, Biermann Tobias, Calzolari Francescopiero, Chen Huilin, Conil Sebastien, Cristofanelli Paolo, Delmotte Marc, Hatakka Juha, Heliasz Michal, Hermansen Ove, Komínková Kateřina, Kubistin Dagmar, Kumps Nicolas, Laurent Olivier, Laurila Tuomas, Lehner Irene, Levula Janne, Lindauer Matthias, Lopez Morgan, Mammarella Ivan, Manca Giovanni, Marklund Per, et al. ,
Project ICOS-CH Phase 2
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Original article (peer-reviewed)

Journal Atmospheric Measurement Techniques
Volume (Issue) 14(1)
Page(s) 89 - 116
Title of proceedings Atmospheric Measurement Techniques
DOI 10.5194/amt-14-89-2021

Open Access

URL http://doi.org/10.5194/amt-14-89-2021
Type of Open Access Publisher (Gold Open Access)

Abstract

Abstract. The Integrated Carbon Observation System (ICOS) is a pan-European research infrastructure which provides harmonized and high-precision scientific data on the carbon cycle and the greenhouse gas budget. All stations have to undergo a rigorous assessment before being labeled, i.e., receiving approval to join the network. In this paper, we present the labeling process for the ICOS atmosphere network through the 23 stations that were labeled between November 2017 and November 2019. We describe the labeling steps, as well as the quality controls, used to verify that the ICOS data (CO2, CH4, CO and meteorological measurements) attain the expected quality level defined within ICOS. To ensure the quality of the greenhouse gas data, three to four calibration gases and two target gases are measured: one target two to three times a day, the other gases twice a month. The data are verified on a weekly basis, and tests on the station sampling lines are performed twice a year. From these high-quality data, we conclude that regular calibrations of the CO2, CH4 and CO analyzers used here (twice a month) are important in particular for carbon monoxide (CO) due to the analyzer's variability and that reducing the number of calibration injections (from four to three) in a calibration sequence is possible, saving gas and extending the calibration gas lifespan. We also show that currently, the on-site water vapor correction test does not deliver quantitative results possibly due to environmental factors. Thus the use of a drying system is strongly recommended. Finally, the mandatory regular intake line tests are shown to be useful in detecting artifacts and leaks, as shown here via three different examples at the stations.
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