日本地球惑星科学連合2018年大会

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[JJ] 口頭発表

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-AS07] 成層圏・対流圏過程とその気候への影響

2018年5月23日(水) 10:45 〜 12:15 A07 (東京ベイ幕張ホール)

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

11:45 〜 12:00

[AAS07-11] Climatological aspects of the accumulation of high potential temperature airmass just below the tropopause over the Aisan monsoon region

*徹 寺尾1 (1.香川大学教育学部)

キーワード:アジア夏季モンスーン、高温位気体、顕熱潜熱加熱

Asian summer monsoon system is the most prominent monsoon circulation on the current earth, giving impacts on atmospheric general circulation including stratosphere. In this Asian summer monsoon region, high potential temperature airmass is accumulated in strongly closed anti-cyclonic circulation in the Tibetan High, which is centered at around the Tibetan Plateau and touched with the westerly jet to the north. The present study focuses on this remarkable accumulation of high potential temperature airmass just below the tropopause in the Asian summer monsoon system.
This high potential temperature airmass should be originated from the high equivalent potential temperature airmass produced in the lower troposphere through the sensible and latent heating at the earth surface. This hypothesis is also supported by many research that elicidated the accumulation of a variety of chemical tracers that is originated from land surface (Park et al. 2008; Pan et al. 2016; Chandra et al. 2017).
Accumulated high potential temperature airmass just below the tropopause over the Asian summer monsoon region belongs to the "middle world" (Hoskins 1991), connected along the isentropic surface with the stratosphere. Therefore, the role of the Asian summer monsoon on the troposphere-stratosphere exchange was discussed in the literature (Chen 1995; Dunkerton 1995; Postel and Hitchmann 1999; Terao 1999).
In the present study, the climatological aspects of the high potential temperature airmass accumulated just below the tropopause in the Asian summer monsoon region was analyzed using reanalysis datasets. It was shown that the accumulation of high potential temperature airmass in the Tibetan High is exceptionally prominent compared with other region and seasons (Fig. 1).
To uncover the origin of high potential temperature airmass, the present paper investigated the production process of the high equivalent potential temperature airmass in the atmospheric boundary layer. Espacially the present paper focused on the Northeastern Indian subcontinent, which is near the center of the Tibetan High, and known as strong diabatic heating region (Xavier et al. 2009).
The climatological aspects of the atmospheric structure just below the tropopause will be discussed intimately related with the land-atmosphere interaction including the heating process of the atmospheric boundary layer. The important expected contribution of port MAHASRI research intiative will also be discussed.
Acknowledgment: Part of this study was supported by the JSPS KAKENHI (No. 26220202).