Atmospheric CO<sub>2</sub>, δ(O<sub>2</sub>/N<sub>2</sub>) and δ<sup>13</sup>CO<sub>2</sub> measurements at Jungfraujoch, Switzerland: results from a flask sampling intercomparison program

Abstract

Abstract. We present results from an intercomparison program of CO2, δ(O2/N2) and δ13CO2 measurements from atmospheric flask samples. Flask samples are collected on a bi-weekly basis at the High Altitude Research Station Jungfraujoch in Switzerland for three European laboratories: the University of Bern, Switzerland, the University of Groningen, the Netherlands and the Max Planck Institute for Biogeochemistry in Jena, Germany. Almost 4 years of measurements of CO2, δ(O2/N2) and δ13CO2 are compared in this paper to assess the measurement compatibility of the three laboratories. While the average difference for the CO2 measurements between the laboratories in Bern and Jena meets the required compatibility goal as defined by the World Meteorological Organization, the standard deviation of the average differences between all laboratories is not within the required goal. However, the obtained annual trend and seasonalities are the same within their estimated uncertainties. For δ(O2/N2) significant differences are observed between the three laboratories. The comparison for δ13CO2 yields the least compatible results and the required goals are not met between the three laboratories. Our study shows the importance of regular intercomparison exercises to identify potential biases between laboratories and the need to improve the quality of atmospheric measurements.

Preparation of primary standard mixtures for atmospheric oxygen measurements with less than 1 µmol mol−1 uncertainty for oxygen molar fractions

“…As the O 2 and Ar molar fractions in air are 20.946 % and 0.943 %, respectively, a respective change of 4.8 and 107 per meg in δ(O 2 /N 2 ) and δ(Ar/N 2 ) corresponds to a change of 1 µmol mol −1 in molar fractions of O 2 and Ar. Reported peak-to-peak amplitudes of seasonal cycles and trends in atmospheric δ(O 2 /N 2 ) were within the range of 50-150 per meg (10-30 µmol mol −1 for O 2 molar fractions) and −20 per meg yr −1 (−4 µmol mol −1 yr −1 for O 2 molar fractions; Keeling et al, 1993;Battle et al, 2000;van der Laan-Luijkx et al, 2013). To monitor these slight variations, the development of primary standard mixtures with standard uncertainty of 5 per meg for O 2 /N 2 ratios (1 µmol mol −1 for O 2 molar fractions) or less (Keeling et al, 1993;WMO, 2016) is required.…”

“…Observation of atmospheric O 2 molar fractions provides important information about the global carbon cycle (Keeling and Shertz, 1992;Bender et al, 1996;Keeling et al, 1996Keeling et al, , 1998aStephens et al, 1998;Battle et al, 2000;Manning and Keeling, 2006). For example, long-term observation allows the estimation of land biotic and oceanic CO 2 uptake (Manning and Keeling, 2006;Tohjima et al, 2008;Ishidoya et al, 2012a, b). Various measurement techniques have been developed for this purpose, including the utilization of interferometry (Keeling et al, 1998b), mass spectrometry (Bender et al, 1994;Ishidoya et al, 2003;Ishidoya and Murayama, 2014), a paramagnetic technique (Manning et al, 1999;Aoki et al, 2018;Ishidoya et al, 2017), a vacuum-ultraviolet absorption technique (Stephens et al, 2003), gas chromatography (Tohjima, 2000), and a method utilizing fuel cells (Stephens et al, 2007;Goto et al, 2013).…”

“…This reference scale is determined based on O 2 /N 2 ratios in primary standard mixtures filled in highpressure cylinders and is considered to be sufficiently stable during the observation period (e.g. Keeling et al, 1998b;Tohjima et al, 2008;Ishidoya et al, 2012b). However, there are many deterioration risks of the O 2 /N 2 ratio in aluminium cylinders used for reference air and the primary standard mixtures.…”

“…Moreover, the molar fractions of all constituents in the HPOs were validated by comparing the gravimetric value with the measured values of the CO 2 mole fraction, Ar/N 2 ratio, and O 2 /N 2 ratio. In order to validate the scale of O 2 /N 2 ratio at the National Institute of Advanced Industrial Science and Technology (AIST) determined using the HPOs prepared in this study, the annual average of O 2 /N 2 ratios in 2015 at Hateruma island (24 • 03 N, 123 • 49 E; Japan) obtained from our measurements of air samples was preliminarily compared with the annual average of O 2 /N 2 ratios in 2015 at Hateruma island on scale of the National Institute for Environmental Studies (NIES) determined by Tohjima et al (2005Tohjima et al ( , 2008. Ad-ditionally, the molar fractions for atmospheric Ar and O 2 in air samples were determined using the HPOs and compared with previously reported values.…”

Hypercapnia modulates cAMP signalling and cystic fibrosis transmembrane conductance regulator‐dependent anion and fluid secretion in airway epithelia

“…Carbon dioxide constitutes 0.04% by volume of the Earth's atmosphere (van der Laan‐Luijkx et al . ) and has major roles in plant, prokaryote and animal biology (Cummins et al . ).…”