Dynamical processes in the mesosphere and the lower thermosphere during sudden stratospheric warmings

2015 Fiscal Year Final Research Report

• Project/Area Number: 24340113
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Kyushu University
• Principal Investigator: HIROOKA Toshihiko 九州大学, 理学(系)研究科(研究院), 教授 (90253393)
• Co-Investigator(Kenkyū-buntansha): MIYOSHI Yasunobu 九州大学, 大学院理学研究院, 准教授 (20243884) ; KAWATANI Yoshio 海洋研究開発機構, 統合的気候変動予測研究分野, 主任研究員 (00392960) ; IWAO Koki 熊本高等専門学校, 共通教育科(八代キャンパス), 准教授 (80396944)
• Co-Investigator(Renkei-kenkyūsha): WATANABE Shingo 海洋研究開発機構, シームレス環境予測研究分野, 分野長 (50371745)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 成層圏突然昇温 / 中間圏 / 下部熱圏 / 半年周期振動 / 大気波動

Outline of Final Research Achievements

In this study, in order to clarify the stratosphere-mesosphere-lower thermosphere dynamical coupling processes during sudden stratospheric warming (SSW) events, we make dynamical analyses of the general circulation up to the mesopause level on the basis of Aura Microwave Limb Sounder data. It is found that large-scale waves are strengthened in the mesosphere due to changing background wind structure prior to the SSW occurrence and the waves could significantly contribute to general circulation changes in the mesosphere as well as in the lower thermosphere. In addition, during SSW events, residual mean poleward flows are enhanced to lead to equatorial temperature perturbations consisting of a cooling in the stratosphere and a warming in the mesosphere. These temperature perturbations are found to modulate the equatorial semiannual oscillation with two separate out-of-phase maxima centered near the stratopause and the upper mesosphere through the thermal wind balance at the equator.

Free Research Field

気象力学・中層大気科学