[A-AS04] Extreme Events and Mesoscale Weather: Observations and Modeling

[AAS04-08] 日本周辺で発生する竜巻の環境場解析。近年の傾向と将来変化。

*川添 祥¹、稲津 將¹、藤田 実季子²、杉本 志織²、岡田 靖子³、渡辺 真吾² (1.北海道大学、2.海洋研究開発機構、3.気象庁気象研究所)

キーワード：竜巻、将来予測、大規模アンサンブル、極端現象

Despite their socio-economic impacts, little is known about how tornadic activity in Japan has changed over the last several decades or how they may change in future climates. To investigate this, we first examine environmental conditions associated with reported tornados in Japan by using pseudo-soundings from the high-resolution fifth-generation ECMWF reanalysis. Discriminators of F2+ tornado environments are determined by computing thermodynamic (convective available potential energy, convective inhibition, lifting condensation level, and the K-index), kinematic (bulk wind difference and storm-relative helicity), and multivariate tornado parameters (energy helicity index, K-helicity index, and the significant tornado parameter). Consistent with previous studies, F2+ tornadoes occur in environments with higher instability and helicity but are better distinguished when using multivariate tornado parameters. Recent trends (1979-2021) indicate that F2+ tornado environments have increased significantly in some regions over the last four decades, though variability exists in their magnitude based on region or the tornado parameter utilized. We also examined future changes in F2+ tornado environments using the 2-K warming scenario from the database for Policy Decision-making for Future climate change. Results depict a robust increase in F2+ environments in almost all regions in Japan, indicating the potential for more tornadoes to occur in the future.