[A-AS10] 成層圏・対流圏過程とその気候への影響

[AAS10-P06] Zonally asymmetric tropopause height trend in the subtropical Indian-Pacific sector

*石田 悠貴¹、浮田 甚郎²、本田 明治³ (1.新潟大学 自然科学研究科 博士後期課程、2.新潟大学 理学部、3.新潟大学理学部フィールド科学人材育成プログラム)

キーワード：対流圏界面、ENSO、長期トレンド

Tropopause variability provides key information on dynamical coupling and exchanges of the mass and chemical species between the stratosphere and troposphere. Its increasing trend has been linked to global warming of the troposphere (Santer et al. 2003; Seidel and Randel 2006). There are however notable regional differences in the trend. A zonally asymmetric pattern of the trend in boreal winter has been identified in the subtropical Indian-Pacific sector (Wilcox et al. 2012), one with an increasing trend over the southeast Asia and the other with a decreasing trend in the central Pacific. Based on an analysis on the JRA-55 reanalysis data over the period of 1979-2017 we found that a highly resembling pattern emerges as the leading EOF mode of the interannual variation in the detrended tropopause height field (r = 0.79 between the PC1 and NINO3.4). Focusing on the signature over the southeast Asia, we examined possible mechanisms, including a longitudinally restricted local Hadley circulation. At the meeting we shall discuss the results from this analysis and a potential upper tropospheric transient eddy effect.