[A-AS08] 成層圏―対流圏相互作用

[AAS08-P02] Laplace's Atmosphere: An Array of Ringing Modes Discovered in Global Reanalysis Data

*坂崎 貴俊¹、Hamilton Kevin² (1.京都大学　大学院理学研究科、2.ハワイ大学　国際太平洋研究センター)

キーワード：ノーマルモード、自由振動、地上気圧、大気再解析

We used newly-available ERA-5 hourly global reanalyses to examine the variations of atmospheric circulation on global scales and high frequencies. The space-time spectra of surface pressure displays a typical red background spectrum but also a striking number of isolated peaks. Some peaks represent astronomically forced tides but we show that most peaks are manifestations of the ringing of randomly excited global scale resonant modes. A few such modes have been tentatively identified in earlier observational investigations, but we demonstrate the existence of the full array of normal mode oscillations with periods as short as 2 hours. This is a powerful and uniquely detailed confirmation of the predictions of the theory of global oscillations that has its roots in the work of Laplace two centuries ago.