Study on extreme events of polar stratospheric temperature change and their long term variability

2016 Fiscal Year Final Research Report

• Project/Area Number: 25800261
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Mie University (2016); The University of Tokyo (2013-2015)
• Principal Investigator: Nishii Kazuaki 三重大学, 生物資源学研究科, 准教授 (50623401)
• Research Collaborator: Orsolini Yvan J. ノルウェー大気科学研究所 ; NAKAMURA Hisashi 東京大学, 先端科学技術研究センター, 教授
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: 成層圏突然昇温 / 成層圏極端現象 / 北大西洋パターン / 中緯度海洋前線 / 海氷 / 十年規模変動

Outline of Final Research Achievements

In winter, temperatures in the Arctic stratosphere experience large variability. The duration of each extreme temperature event differs from event to event, and the frequency of those extreme events shows decadal-scale variability. We classified stratospheric extreme events into short and long events, and found that the duration is dependent on the duration of associated incoming planetary waves from the troposphere. The intensity of the planetary waves depends on tropospheric local circulation anomalies in particular domains. We investigated the mechanism of the Western Pacific pattern that affects the intensity of planetary waves. We also performed ensemble experiments of an atmospheric general circulation model to investigate factors that affect the Arctic stratosphere under various boundary conditions. We found that the midlatitude oceanic front can be one of such factors.

Free Research Field

対流圏と成層圏の大気力学