日本地球惑星科学連合2019年大会

講演情報

[J] ポスター発表

セッション記号 A (大気水圏科学) » A-AS 大気科学・気象学・大気環境

[A-AS05] 成層圏・対流圏過程とその気候への影響

2019年5月29日(水) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:河谷 芳雄(国立研究開発法人海洋研究開発機構)、渡辺 真吾(国立研究開発法人海洋研究開発機構)、関谷 高志(国立研究開発法人 海洋研究開発機構)、佐藤 薫(東京大学 大学院理学系研究科 地球惑星科学専攻)

[AAS05-P10] Analysis of specific energy in zonal currents focusing on the analogy between jet stream and open channel flow

*北野 慈和1山田 朋人2 (1.一般財団法人 電力中央研究所、2.北海道大学大学院工学研究院)

キーワード:大気ブロッキング、偏西風ジェット、開水路流れ

Atmospheric blocking is one of the important causes of meteorological extremes in mid-latitude, such as cold spells, heat waves and long-term heavy rainfalls. Rossby (1950) focused on dynamical analogies between the hydraulic jump in open channel flow and the atmospheric blocking in jet stream, and proposed a theoretical formula to explain the two dynamically possible states in zonal currents which are compatible with supercritical and subcritical flow in an open channel flow. Armi (1989) focused on the specific energy flux in zonal currents and showed that a dimensionless parameter, which is called Froude/Rossby number, is analogous to the Froude number of open channel flow. Kitano and Yamada (2017) extended these theories to realistic conditions in atmosphere and showed a relationship between typical blocking flow and specific energy flux in jet stream. In this study, we analyzed several blocking episodes using specific energy flux and found energetic signals over Japan and its surroundings before Pacific blocking occasions. These signals may contribute to prediction on blocking.