[A-AS05] 成層圏・対流圏過程とその気候への影響

[AAS05-02] 熱帯成層圏界面領域における半年周期振動の運動量収支解析

*冨川 喜弘^1,2、V. Harvey³、John Knox⁴、藤原 正智⁵ (1.国立極地研究所、2.総合研究大学院大学、3.コロラド大学ボルダー校、4.ジョージア大学、5.北海道大学)

キーワード：成層圏界面、半年周期振動、再解析

Meteorological reanalysis data have been updated and improved in the past decade, which are pretty useful for climate and meteorological studies. Their comprehensive evaluation is going underway as the SPARC Reanalysis Intercomparison Project (S-RIP). This study reports the momentum budget of semiannual oscillation around the tropical stratopause for four kinds of the latest reanalysis data (i.e., MERRA, MERRA2, ERA-Interim, and JRA55) as a part of S-RIP. They showed that, while the westerly acceleration is primarily due to unresolved wave drag (i.e. gravity wave drag), the easterly acceleration is induced by momentum transport due to meridional circulation and resolved wave drag. This feature is consistent with previous studies based on simulation and observation. However, the contribution of unresolved wave drag is maximized in MERRA/MERRA2 later than in ERA-Interim/JRA55. We discuss the difference between the latest reanalyses and its impact on the tropical dynamics.