Atmospheric CH4 and N2O data from the flask air sampling over Novosibirsk

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

2024/02/16

1997/07/24 - 2022/01/28

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

409 KB

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English

CH₄ and N₂O mixing ratios

From Jul. 24th, 1997 (ongoing)

Vertical: 0.5 - 7.0 km

Air sampling was carried out approximately once per month using a research plane (Antonov AN-30) operated by the Institute of Atmospheric Optics (Antokhin et al., 2012) at the altitudes of 7.0, 5.5, 4.0, 3.0, 2.0, 1.5, 1.0, and 0.5 km over the pine forest area between Novosibirsk (55°03′N, 82°57′E) and Kamen-na-Obi (53°47′N, 81°20′E). However, on July 24, 1997, October 24, 1997, May 26, 1998, July 23, 1998, August 28, 1998, and September 29, 2000, sampling was conducted over Plotnikovo (56°52′N, 83°05′E). We used a chartered aircraft (Tupolev Tu-134) from 25 March 2011 to 18 June 2017. Since 26 October, we have used another chartered aircraft (Yak-40).
Two samples were collected at each altitude during the level flight, and the sampling interval was 2–3 min. Flights were usually performed around noon or in the afternoon local time. The air sample was introduced into the cockpit through an inlet placed in front of the engine exhaust and pressurized into a Pyrex glass flask at about +0.2 MPa over cabin pressure using an electric diaphragm pump. The stopcocks of the glass flasks and the diaphragm pump were operated manually.
The air samples were sent to NIES and analyzed for CH₄ concentration using GC-FID. The system used was HP5890 (Hewlett-Packard Comp.), followed by Agilent 7890A (Agilent Technologies, Inc.) for the samples collected after 18 March 2014. Each gas sample was analyzed three times if possible. The repeatability of the measurements was 1.3 ppb and 0.9 ppb based on the repeated measurements of dry cylinder air. The concentration was determined against the NIES 94 CH₄ scale, which is ~3.7 ppb higher than the WMO-CH₄-X2004 scale in the concentration range of 1755.5–1820.2 ppb (Round Robin Comparison Experiment; http://www.esrl.noaa.gov/gmd/ccgg/wmorr/).
The N₂O measurements were done by Agilent 6890 with an ECD for the sample obtained until 16 November 2011 and μECD from 13 December 2011. The precision was 0.18 ppb for the ECD and 0.43 ppb for the μECD based on the repeated measurements of dry cylinder air. The working standard gases were calibrated against the NIES 96 N₂O scale.
[References]
Antokhin, P. N., et al. (2012), Optik-É AN-30 aircraft laboratory for studies of the atmospheric composition, J Atmos Ocean Tech, 29(1), 64-75, doi:10.1175/2011JTECHA1427.1.

The average value is described for samples with multiple measurements; the analysis value is expressed as is for samples with a single measurement. For the samples measured repeatedly, we set a criterion that the standard deviation (SD) of repeated measurements of less than two times the precision was valid (dependent on the GC systems); that is, we did not show the CH₄ data whose SD was more significant than 2.6 ppb for the period from March 2005 to January 2014, and 1.8 ppb from April 2014 to December 2021. As for N₂O, 0.36 ppb from March 2005 to November 2011 and 0.86 ppb from December 2011 to December 2021.

[Free keywords]

[2024/02/16]

Miyuki Yanai
National Institute for Environmental Studies (NIES)

Mikhail Arshinov
V.E. Zuev Institute of Atmospheric Optics, Russia Academy of Sciences, Siberian Branch

Sasakawa, M., T. Machida, K. Ishijima, M. Arshinov, P. K. Patra, A. Ito, S. Aoki, and V. Petrov (2017), Temporal Characteristics of CH₄ Vertical Profiles Observed in the West Siberian Lowland Over Surgut From 1993 to 2015 and Novosibirsk From 1997 to 2015, Journal of Geophysical Research-Atmospheres, 122(20), 11261-11273, doi:10.1002/2017jd026836.

The observations were supported by a fund for global environmental monitoring by CGER, NIES.

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