Semi-continuous observational data for atmospheric CO2 and CH4 mixing ratios at Yakutsk

Motoki Sasakawa^*1 (orcid.org/0000-0003-2273-5131),Toshinobu Machida^*1(orcid.org/0000-0003-3312-8775)
^*1Earth System Division, National Institute for Environmental Studies (NIES)

2023/11/17

2005/05/22 - 2013/03/07

NIES
Email: cgerdb_admin(at)nies.go.jp

24 MB

ver.1.0 (Last updated: 2023/11/17)

English

CO₂ and CH₄ mixing ratios

2005/05/22 - 2013/03/07

62.0886°N, 129.3558°E

Elevation: 264 m
Air inlet heights: 11 m, 77 m

Each sample inlet was positioned approximately 3 m from the tower at the end of an extension arm. Atmospheric air was delivered via a decabon tube by a diaphragm pump (model N86KNE, KNF, Germany) into the freight container with insulators to reduce temperature variation and dried with (1) adiabatic expansion in a glass water trap, (2) a semi-permeable membrane dryer (model PD-625–24SS, Permapure, USA) and (3) magnesium perchlorate. The dehumidified air was then introduced into a non-dispersive infrared analyzer (model LI-820, LI-COR, USA; a model LI-7000 was used until September 2008 at BRZ) and a CH₄ semiconductor sensor at a constant flow rate of 35 cm3 min−1 using a mass flow controller (model SEC-E40, STEC, Japan). The CH₄ semiconductor sensor based on a tin dioxide natural gas leak detector was developed by Suto and Inoue (2010) to measure atmospheric CH₄ concentration in areas lacking the sufficient infrastructure to sustain a conventional measurement system, such as a large power source, carrier gas supply, and temperature-stabilized laboratory. The sensor has been verified against a gas chromatograph equipped with a flame ionization detector (Suto and Inoue, 2010). Three standard gases were prepared from pure CO₂ and CH₄ diluted with purified air, and their concentrations were determined against the NIES 09 CO₂ scale (Machida et al., 2011) and NIES 94 CH₄ scale. Each scale was established by a series of standard gases prepared by the gravimetric method. The NIES 94 CH₄ scale is 4.1 ppb higher than the WMO-CH₄-X2004A scale at a concentration of 1736.3 ppb and 5.5 ppb higher at 1941.9 ppb (Round Robin 6 Comparison Experiment; http://www.esrl.noaa.gov/gmd/ccgg/wmorr/). We used in situ compressed air as a reference gas to reduce the consumption of the three standard gases because this system operates continuously, and it isn't easy to replace the standard gas cylinders in Siberia. Twice a day, the three standard gases were analyzed over an hour, and the signal baseline drifts of the standard gases in 11 h were estimated with the temporal variation of the reference gas signals.
[References]
Machida, T., Tohjima, Y., Katsumata, K. and Mukai, H.: A new CO₂ calibration scale based on gravimetric one‐step dilution cylinders in National Institute for Environmental Studies – NIES 09 CO₂ Scale, in Report of the 15th WMO/IAEA Meeting of Experts on Carbon Dioxide, Other Greenhouse Gases and Related Tracers Measurement Techniques (ed. Willi A. Brand). Jena, Germany, September 7–10, 2009, WMO/GAW Report No. 194, 165–169, 2011.
Suto, H. and Inoue, G.: A New Portable Instrument for In Situ Measurement of Atmospheric Methane Mole Fraction by Applying an Improved Tin Dioxide-Based Gas Sensor, J Atmos Ocean Tech, 27, 1175-1184, doi:10.1175/2010jtecha1400.1, 2010.

The air-sampling flow path was rotated every 20 min; that is, the high inlet was sampled from hh:00, the low inlet from hh:20, and the reference gas from hh:40. The final three-minute readouts were averaged.

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[2023/11/17]

Noritsugu Tsuda
Global Environmental Forum

Sasakawa, M., Shimoyama, K., Machida, T., Tsuda, N., Suto, H., Arshinov, M., Davydov, D., Fofonov, A., Krasnov, O., Saeki, T., Koyama, Y., and Maksyutov, S.(2010): Continuous measurements of methane from a tower network over Siberia, Tellus Series B-Chemical and Physical Meteorology, 62, 403-416, doi:10.1111/j.1600-0889.2010.00494.x.

The measurements were financially supported by the Global Environmental Research Coordination System from the Ministry of the Environment of Japan.

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