On the temporal variations of the atmospheric methane concentration by precise measurements of carbon and hydrogen isotopes.

• Project/Area Number: 15H03722
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Tohoku University
• Principal Investigator: MORIMOTO Shinji 東北大学, 理学研究科, 教授 (30270424)
• Co-Investigator(Kenkyū-buntansha): 青木 周司 東北大学, 理学研究科, 教授 (00183129) ; 後藤 大輔 国立極地研究所, 研究教育系, 助教 (10626386)
• Research Collaborator: ISHIJIMA kentaro
• Project Period (FY): 2015-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥17,420,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥4,020,000); Fiscal Year 2018: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2017: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000); Fiscal Year 2016: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000); Fiscal Year 2015: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000)
• Keywords: メタン / 温室効果気体 / 同位体比 / 環境動態

Outline of Final Research Achievements

Systematic and precise measurements of the concentration and carbon and hydrogen isotope ratios of atmospheric methane were conducted by analyzing air samples regularly collected at northern high latitude sites, Antarctic station and in the western Pacific region, and their short-term, seasonal and long-term variations were identified. Simultaneous analysis with the concentration and isotope ratios suggested that the methane from microbial source could be responsible for the observed regrowth of the methane concentration after 2006 and after 2014. Simulations of the isotope ratios of the atmospheric methane with a three-dimensional atmospheric chemistry-transport model and prescribed methane inventory data gave isotopically lighter results than the observed values in this study. This indicates that the contribution ratio of each source category in the prescribed inventory is different from the real methane sources.

Academic Significance and Societal Importance of the Research Achievements

大気中メタン濃度観測のみからはメタン放出源に関する情報が得られないが、その炭素・水素同位体比の同時高精度観測を行うことにより、メタン放出源の変動に関する情報が得られることが示された。現在の地球表層におけるメタン循環を明らかにし、将来のメタン濃度予測精度を高めるために、メタン濃度と同位体比の同時観測が非常に有効である。

Research Products

• [Int'l Joint Research] Environment and Climate Change Canada(カナダ)
• [Int'l Joint Research] Environment and Climate Change Canada(カナダ)
• [Int'l Joint Research] 環境省研究所(カナダ)
• [Int'l Joint Research] Meteorological Service of Canada(カナダ)
• [Journal Article] Temporal variations of the mole fraction, carbon and hydrogen isotope ratios of atmospheric methane in the Hudson Bay Lowlands, Canada. (2018)
  • Author(s): Fujita, R., S. Morimoto, T. Umezawa, K. Ishijima, P. K. Patra, D. E. J. Worthy, D. Goto, S. Aoki and T. Nakazawa
  • Journal Title: J. Geophys. Res. Volume: 123 Issue: 9 Pages: 4695-4711
  • DOI: 10.1002/2017jd027972
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Intercomparisons of d13C and dD measurements of atmospheric CH4 for combined use of datasets from different laboratories (2018)
  • Author(s): Umezawa, T., C.A.M. Brenninkmeijer, T. Roeckmann, C. van der Veen, S. C. Tyler, R. Fujita, S. Morimoto, et al.
  • Journal Title: Atmos. Meas. Tech. Volume: －
  • DOI: 10.5194/amt-2017-281
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Long-term variations of the mole fraction and carbon isotope ratio of atmospheric methane observed at Ny-Aalesund, Svalbard from 1996 to 2013 (2017)
  • Author(s): Morimoto Shinji、Fujita Ryo、Aoki Shuji、Goto Daisuke、Nakazawa Takakiyo
  • Journal Title: Tellus Volume: 69 Issue: 1 Pages: 1380497-1380497
  • DOI: 10.1080/16000889.2017.1380497
  • Peer Reviewed
• [Journal Article] Seasonal and short-term variations in atmospheric potential oxygen at Ny-Aalesund, Svalbard (2017)
  • Author(s): Goto, D., S. Morimoto, S. Aoki, P.K. Patra and T. Nakazawa
  • Journal Title: Tellus Volume: 69B Issue: 1 Pages: 1311767-1311767
  • DOI: 10.1080/16000889.2017.1311767
  • Peer Reviewed / Open Access
• [Journal Article] Ship-based observations of atmospheric potential oxygen and regional air-sea O2 flux in the northern North Pacific and the Arctic Ocean (2016)
  • Author(s): Ishidoya, S., H. Uchida, D. Sasano, N. Kosugi, S. Taguchi, M. Ishii, S. Morimoto, Y. Tohjima, S. Nishino, S. Murayama, S. Aoki, K. Ishijima, R. Fujita, D. Goto and T. Nakazawa
  • Journal Title: Tellus Volume: 68B Issue: 1 Pages: 29972-29972
  • DOI: 10.3402/tellusb.v68.29972
  • Peer Reviewed / Open Access
• [Journal Article] Development of an atmospheric N2O isotope model, optimization procedure, and application to source estimation (2015)
  • Author(s): Ishijima, K., M. Takigawa, K. Sudo, S. Toyoda, N. Yoshida, T. Röckmann, J. Kaiser, R. G. Prinn, S. Aoki, S. Morimoto, S. Sugawara and T. Nakazawa
  • Journal Title: Atmos. Chem. Phys. Discuss. Volume: 15
  • DOI: 10.5194/acpd-15-19947-2015
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Temporal variations of the mole fraction and carbon isotope ratio of atmospheric methane observed at Ny-Aalesund, Svalbard. (2018)
  • Author(s): Morimoto, S., R. Fujita, S. Aoki, D. Goto and T. Nakazawa
  • Organizer: 14th ICACGP/15th IGAC Science Conference
  • Int'l Joint Research
• [Presentation] Measurements of d13C and dD of atmospheric CH4 in the northern North Pacific and the Arctic Ocean and interpretation of Arctic CH4 sources (2018)
  • Author(s): Fujita, R., S. Morimoto, S. Ishidoya, Y. Tohjima, K. Ishijima, S. Aoki and T. Nakazawa
  • Organizer: 14th ICACGP/15th IGAC Science Conference
  • Int'l Joint Research
• [Presentation] Temporal variations of the global CH4 sources estimated by mole fraction, carbon and hydrogen isotope ratios of atmospheric CH4 and an atmospheric chemistry transport model (2018)
  • Author(s): Fujita, R., S. Maksyutov, S. Morimoto, S. Aoki, T. Nakazawa, H.-S. Kim, T. Umezawam D. Goto, M. Sasakawa and T. Machida
  • Organizer: 日本地球惑星科学連合大会
• [Presentation] スバールバル諸島ニーオルスン基地における大気中二酸化炭素、メタン、一酸化炭素濃度の変動 (2018)
  • Author(s): 村山昌平、森本真司、後藤大輔、青木周司、中澤高清、石島健太郎、前田高尚、石戸谷重之、菅原敏、藤田遼
  • Organizer: 日本気象学会春季大会
• [Presentation] Variations of atmospheric methane and its carbon and hydrogen isotopic ratios observed in the upper troposphere/lowermost stratosphere over the Eurasian Continent (2017)
  • Author(s): Fujita, R., S. Morimoto, Y. Inai, S. Aoki, T. Machida, Y. Sawa, H. Matsueda, Y. Niwa, K. Tsuboi, K. Katsumata, T. Umezawa and T. Nakazawa
  • Organizer: 10th International Carbon Dioxide Conference
  • Int'l Joint Research
• [Presentation] Japanese observation programs of atmospheric greenhouse gases in polar regions (2017)
  • Author(s): Goto, D., S. Morimoto, S. Aoki, T. Nakazawa, S. Ishidoya, S. Murayama, G. Hashida and T. Yamanouchi
  • Organizer: 19th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases, and Related Measurement Techniques
  • Int'l Joint Research
• [Presentation] Observations of mole fractions and isotope ratios of the atmospheric greenhouse gases (2017)
  • Author(s): Morimoto, S., D. Goto, R. Fujita and S. Aoki
  • Organizer: 8th Symposium on Polar Science
  • Int'l Joint Research / Invited
• [Presentation] Atmospheric methane variations observed in the upper troposphere/lowermost stratosphere over the Eurasian continent and their interpretation based on the carbon and hydrogen isotopic ratios (2017)
  • Author(s): Fujita, R., S. Morimoto, Y. Inai, S. Aoki, T. Machida, Y. Sawa, H. Matsueda, Y. Niwa, K. Tsuboi, K. Katsumata, T. Umezawa and T. Nakazawa
  • Organizer: 日本地球惑星科学連合大会
• [Presentation] スバールバル諸島ニーオルスンにおけるメタン炭素同位体比の長期変化 (2016)
  • Author(s): 森本真司、藤田遼、青木周司、中澤高清、山内恭
  • Organizer: 第7回極域科学シンポジウム
  • Place of Presentation: 国立極地研究所、東京都立川市
  • Year and Date: 2016-11-29
• [Presentation] カナダ・チャーチルにおける炭素・水素同位体比の観測から推定された大気中CH4濃度変動にtaiする北方湿地の寄与 (2016)
  • Author(s): 藤田遼、森本真司、梅澤拓、石島健太郎、P.K. Patra, D.E.J. Worthy
  • Organizer: 第7回極域科学シンポジウム
  • Place of Presentation: 国立極地研究所、東京都立川市
  • Year and Date: 2016-11-29
• [Presentation] ユーラシア大陸上空の対流圏界面領域における大気中CH4濃度とその炭素・水素同位体比の季節変動の解析 (2016)
  • Author(s): 藤田遼、森本真司、青木周司、町田 敏暢，澤 庸介，松枝 秀和，坪井一寛，勝又啓一，梅澤拓，中澤高清
  • Organizer: 日本気象学会秋季大会
  • Place of Presentation: 名古屋大学、愛知県名古屋市
  • Year and Date: 2016-10-26
• [Presentation] Source identification of atmospheric methane variations at Churchill, Canada using carbon and hydrogen isotope analyses (2016)
  • Author(s): Fujita, R., S. Morimoto, T. Umezawa, K. Ishijima, P.K. Patra, D.E.J. Worthy, D. Goto, S. Aoki and T. Nakazawa
  • Organizer: IGAC Science Conference
  • Place of Presentation: Breckenridge, CO, U.S.A.
  • Year and Date: 2016-09-26
  • Int'l Joint Research
• [Presentation] Regional methane (CH4) emission estimation based on observed atmospheric concentrations (2002-2012) (2016)
  • Author(s): Patra, P. K., T. Saeki, E.J. Dlugokencky, K. Ishijima, T. Umezawa, A. Ito, S. Aoki, S. Morimoto, E.A. Kort, A. Crotwell, K. Ravi Kumar and T. Nakazawa
  • Organizer: 日本地球惑星科学連合大会
  • Place of Presentation: 幕張メッセ、千葉県幕張市
  • Year and Date: 2016-05-22
• [Presentation] 放出源別モデル計算を用いたメタンフラックスの最適化について (2015)
  • Author(s): 石島健太郎、Prabir Patra、Ed Dlugokencky, 伊藤昭彦、町田敏暢、梅澤拓、青木周司 、森本真司、中澤高清
  • Organizer: 日本気象学会秋季大会
  • Place of Presentation: 京都テルサ、京都府京都市
  • Year and Date: 2015-10-28
• [Presentation] カナダ・チャーチルにおける大気中CH4濃度の季節変動とその起源解析 (2015)
  • Author(s): 藤田遼、森本真司、石島健太郎、Prabir Patra、梅澤拓、Doug Worthy、青木周司、中澤高清
  • Organizer: 第21回大気化学討論会
  • Place of Presentation: 東京工業大学、東京都目黒区
  • Year and Date: 2015-10-19
• [Presentation] Methane isotope measurements of CARIBIC air samples and preliminary intercomparison results (2015)
  • Author(s): Umezawa,T., C.A.M. Brenninkmeijer, T. Roeckmann, S.C.Tyler, S. Aoki and S. Morimoto
  • Organizer: InGOS International Conference
  • Place of Presentation: Utrecht, the Netherlands
  • Year and Date: 2015-09-21
  • Int'l Joint Research
• [Remarks] 温室効果気体観測ネットワーク
  • URL: http://caos.sakura.ne.jp/tgr/observation/network-2