Effects of large-scale outflow of low-level cool air originating from the subarctic ocean on the occurrence of extreme events

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04058
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Hirosaki University
• Principal Investigator: Shimada Teruhisa 弘前大学, 理工学研究科, 准教授 (30374896)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 極端現象 / 下層冷気 / 亜寒帯海域 / 冷夏 / 豪雨 / 気象シミュレーション / 衛星観測 / 海上風

Outline of Final Research Achievements

This study investigated the effects of low-level cool air originating from the subarctic oceans on the occurrence of two extreme events in summer. First, the low temperature event in July 2019 was analyzed. The low-level cool air flowed from the Pacific to northern and eastern Japan. In particular, the cool air significantly intruded into the Sendai Plain and the Kanto Plain. Next, we analyzed the distribution and variation of the low-level cool air. In the first half of the heavy precipitation period, the low-level cool air flowed into the Japan Sea from the Okhotsk Sea, whereas, in the latter half, the low-level cool air flowed into the Japan Sea from the south of Hokkaido. Thus, this study clarified the role of low-level cool air originating from the subarctic oceans in the summer climate around Japan.

Free Research Field

気象学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果の学術的意義は、下層冷気の分布と変動という観点から、日本付近で発生した極端現象の発生要因を考察したことである。夏季の亜寒帯海域起源の下層冷気が、記録的な低温や豪雨の発生要因の一つとして挙げられることはあったが、下層冷気の役割についての詳しい研究はこれまでにはほとんどなかった。本研究の成果の社会的意義は、夏季気候の極端化についてのさらなる理解に貢献できることである。社会に大きな影響を与える極端現象に関する理解は、様々な分野（防災、農業、漁業、再生可能エネルギー等）から求められている。