Uncertainty in tropospheric cloud adjustment and instantaneous radiative forcing

• Project/Area Number: 17K05657
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: National Institute for Environmental Studies
• Principal Investigator: Ogura Tomoo 国立研究開発法人国立環境研究所, 地球環境研究センター, 主任研究員 (10370264)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2019: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000); Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2017: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
• Keywords: 気候変化 / 放射強制力 / 対流圏調節 / 気候感度 / 雲 / 降水 / 気候変動

Outline of Final Research Achievements

Projection of climate change by multiple Global Climate Models (GCMs) exhibits a considerable spread among the GCMs, partly because of the spread in the simulated cloud adjustment induced by the atmospheric CO2 increase. The cloud adjustment is a variation in cloud caused by the radiative heating of the atmosphere from the CO2 increase, that occurs before an increase in surface air temperature. A study recently hypothesized that the spread in the cloud adjustment originates from the spread in the radiative heating of the atmosphere from the CO2 increase, diagnosed with the multiple GCMs. To examine the hypothesis, we analyzed output of numerical experiments with 5 GCMs. The obtained results corroborated the hypothesis.

Academic Significance and Societal Importance of the Research Achievements

気候変化への対策（緩和策や適応策）を立案するには、大気中のCO2濃度が変化した場合に気候がどう変わるのか、気候モデルを用いた数値シミュレーションで予測する必要がある。しかし、このような予測は、複数のモデル間で結果が大きくばらつくという問題が知られている。本研究は、予測にばらつきを生じさせる要因の一つとして、気候モデルで診断される放射加熱のばらつきが重要であることを明らかにした。この成果は、予測のばらつきを低減させるための手がかりを与える点に、社会的意義がある。また、大気中のCO2濃度増加に対して雲がどのように応答するか、という問題に対して回答の手がかりを与える点に、学術的意義がある。

Research Products

• [Int'l Joint Research] Met Office Hadley Centre/University of Exeter(英国)
• [Int'l Joint Research] Met Office Hadley Centre/University of Exeter(英国)
• [Int'l Joint Research] 気象局ハドレーセンター/エクセター大学(英国)
• [Journal Article] Description and basic evaluation of simulated mean state, internal variability, and climate sensitivity in MIROC6 (2019)
  • Author(s): Tatebe Hiroaki, et al.
  • Journal Title: Geoscientific Model Development Volume: 12 Issue: 7 Pages: 2727-2765
  • DOI: 10.5194/gmd-12-2727-2019
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Separating the influences of land warming, the direct CO2 effect, the plant physiological effect and SST warming on regional precipitation changes (2019)
  • Author(s): Chadwick, R., D. Ackerley, D. Dommenget, and T. Ogura
  • Journal Title: Journal of Geophysical Research: Atmospheres Volume: 124 Issue: 2 Pages: 624-640
  • DOI: 10.1029/2018jd029423
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Seasonally variant low cloud adjustment over cool oceans (2018)
  • Author(s): Kamae, Y., R. Chadwick, D. Ackerley, M. Ringer, and T. Ogura
  • Journal Title: Climate Dynamics Volume: 52 Issue: 9-10 Pages: 5801-5817
  • DOI: 10.1007/s00382-018-4478-7
  • NAID: 120007127935
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Effectiveness and limitations of parameter tuning in reducing biases of top-of-atmosphere radiation and clouds in MIROC version 5 (2017)
  • Author(s): Ogura, T., H. Shiogama, M. Watanabe, M. Yoshimori, T. Yokohata, J. D. Annan, J. C. Hargreaves, N. Ushigami, K. Hirota, Y. Someya, Y. Kamae, H. Tatebe, and M. Kimoto
  • Journal Title: Geoscientific Model Development Volume: 10 Issue: 12 Pages: 4647-4664
  • DOI: 10.5194/gmd-10-4647-2017
  • NAID: 120007134635
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] A new method for understanding inter-model difference in low cloud feedback (2019)
  • Author(s): Ogura, T. and M. J. Webb
  • Organizer: CFMIP meeting
  • Int'l Joint Research
• [Presentation] 瞬時放射強制力に起因する降水予測の不確実性 (2018)
  • Author(s): 小倉知夫, M. J. Webb, 渡部雅浩, F. H. Lambert, and 對馬洋子
  • Organizer: 日本気象学会秋季大会
• [Presentation] Seasonally variant low cloud adjustment over cool oceans (2018)
  • Author(s): Kamae, Y., R. Chadwick, D. Ackerley, M. Ringer, and T. Ogura
  • Organizer: CFMIP Meeting 2018
  • Int'l Joint Research
• [Presentation] Instantaneous radiative forcing as a contributing factor to the inter-model difference in precipitation adjustment (2017)
  • Author(s): Ogura, T., M. J. Webb, M. Watanabe, F. H. Lambert, and Y. Tsushima
  • Organizer: 2017 Cloud Feedback Model Intercomparison Project meeting
  • Int'l Joint Research
• [Remarks] 研究者紹介
  • URL: https://www.nies.go.jp/researchers/100120.html