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

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The present data set is semi-continuous observational data of CO2 and CH4 mixing ratios at Azovo in western Siberia.


Release date
Temporal coverage
2007/12/27 - 2021/11/02
Data provider
Email: cgerdb_admin(at)
File format
Data volume
45 MB
ver.1.0 (Last updated: 2023/11/17)

Data Set

CO2 and CH4 mixing ratios
Observation period
From 2007/12/27 (ongoing)
54.705°N, 73.0292°E
Elevation: 110 m
Air inlet heights: 29 m, 50 m
Measurement method
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; 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.
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.
Calculation method
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.
[Free keywords]
CO2, CH4, Siberia, tower observation, JR-STATION
Update history
Version 1.0. was released (ver.1.0)


Observation system administrator
Mikhail Arshinov
V.E. Zuev Institute of Atmospheric Optics, Russia Academy of Sciences, Siberian Branch
Data Manager
Noritsugu Tsuda
Global Environmental Forum

References Information

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

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When this data set is referred to in publications, it should be cited in the following format.
Sasakawa et al.(2023), Semi-continuous observational data for atmospheric CO2 and CH4 mixing ratios at Azovo, ver.x.x *1, Earth System Division, NIES,DOI:10.17595/20231117.007. (Reference date*2: YYYY/MM/DD)
*1 The version number is indicated in the name of each data file.
*2 As the reference date, please indicate the date you downloaded the files.
When generally referring to the data of JR-STATION, please also cite Sasakawa et al. (2010).
Sasakawa, M., et al. (2010), Continuous measurements of methane from a tower network over Siberia, Tellus Series B-Chemical and Physical Meteorology, 62(5), 403-416, DOI:10.1111/j.1600-0889.2010.00494.x.
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