How does Arctic sea ice loss shape and amplify extreme cold waves in East Asia?

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H01964
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Kyushu University (2020-2021); The University of Tokyo (2019)
• Principal Investigator: Mori Masato 九州大学, 応用力学研究所, 助教 (00749179)
• Co-Investigator(Kenkyū-buntansha): 西井 和晃 三重大学, 生物資源学研究科, 准教授 (50623401) ; 小坂 優 東京大学, 先端科学技術研究センター, 准教授 (90746398)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 海氷 / 北極 / 地球温暖化 / 異常気象 / 気候変動 / テレコネクション

Outline of Final Research Achievements

Arctic sea ice is rapidly decreasing with global warming, which has been suggested to affect not only Arctic climate but also weather and climate in the midlatitude. This study investigated the impact of Arctic sea-ice loss on the formation and enhancement of extreme cold waves and severe winters that have been occurring frequently in East Asia in recent years, and the mechanisms underlying these events by using numerical model simulation. Although the large scale atmospheric circulation variability that responsible for the East Asian cold winters, named WACE, is basically atmospheric internal variability, a hybrid analysis of observations and muti-model large ensemble simulation showed that a part of the WACE variability is externally forced by sea-ice anomaly. In addition, the comparison of coupled model simulations with the atmosphere-only simulations indicated that the atmosphere-ice coupling processes act to enhance the variance of WACE.

Free Research Field

気候力学

Academic Significance and Societal Importance of the Research Achievements

上記の結果は、WACEパターンに伴う大気循環偏差と海氷偏差との相互作用が、WACEパターン自身の成長に無視できない寄与を果たしていることを示唆している。これはこれまでにない全く新しい知見であり、今後の新しい学術的な展開が期待される。また、東アジアの寒冬の季節予測のさらなる精度向上のためには、大気・海洋だけでなく海氷変動の現実的な予測性能が不可欠である可能性を示唆しており、社会的にも重要な知見であると考える。