GAW Report No. 263
Report of the Fifth Methane Reference Gas Inter-comparison Experiment for Japan from 2018 to 2019
Teruo Kawasaki, Atsuya Kinoshita, Yousuke Sawa, Akihiko Murata, Shinji Morimoto, Shohei Murayama, Toshinobu Machida, Motoki Sasakawa, Kazuhiro Tsuboi
The WCC-JMA organized six rounds of the CH4 reference gas inter-comparison experiments from 2001 to 2019 to quantify differences among CH4 standard scales implemented at each participating laboratory as well as to monitor the long-term stability of standard gases in Asia and the South-West Pacific. In the 5th round inter-comparison for Japan, two reference gas cylinders were circulated in turn to JMA, JAMSTEC, TU, AIST, NIES, MRI, and JMA from September 2018 to April 2019. The measurement results of JAMSTEC and WCC-JMA have shown a good agreement with differences of less than 0.4 ppb for two cylinders, whereas the differences between other laboratories and WCC-JMA ranged from 0.96 to 3.77 ppb, mainly due to differences of CH4 calibration scales.