Elucidation of the occurrence mechanism of downward propagation of planetary waves in the stratosphere and evaluation of its impact on the troposphere

2022 Fiscal Year Final Research Report

• Project/Area Number: 18H01280
• 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: Kyoto University
• Principal Investigator: Mukougawa Hitoshi 京都大学, 理学研究科, 教授 (20261349)
• Co-Investigator(Kenkyū-buntansha): 廣岡 俊彦 九州大学, 理学研究院, 教授 (90253393)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 惑星規模波 / 下方伝播 / 成層圏 / 不安定性 / 対流圏

Outline of Final Research Achievements

Using long-term reanalysis data and numerical simulation based on an atmospheric general circulation model, we investigated characteristics of downward propagation events of stratospheric planetary waves in the Northern Hemisphere winter and their relationship to anomalous weather events. We found that the downward propagation of planetary waves tends to occur in two longitudinal zones in the Western Hemisphere and to occur in two different longitudinal widths. It was also shown that stronger cold waves are associated with the downward propagation of planetary waves in the Western Hemisphere with a wider longitudinal width. The dynamical instability of zonally-asymmetric stratospheric circulation, which relates to the generation of the downward propagation of stratospheric planetary waves, was examined using an atmospheric mechanistic model.

Free Research Field

気象学

Academic Significance and Societal Importance of the Research Achievements

冬季における寒波などの異常気象を引き起こす要因の一つである成層圏惑星波の下方伝播の実態と特徴を明らかにすることができた。特に、下方伝播が西半球で生じやすいことや、生じやすい経度幅は二つあり、より広い経度幅で下方伝播が生ずるとより強い寒波が発生しやすいことを明らかにしたことは意義深い。また、成層圏循環の予測可能性変動が、その力学的安定性でも規定されることを指摘したことは学術的に大変意義深い。