[A-AS08] 成層圏―対流圏相互作用

[AAS08-P05] A statistical analysis of the turbulent kinetic energy dissipation rate estimated from the PMWE spectral width in the Antarctic

*高麗 正史¹、佐藤 薫¹、西村 耕司²、堤 雅基²、佐藤 亨³ (1.東京大学大学院理学系研究科地球惑星科学専攻大気海洋科学講座、2.国立極地研究所・総合研究大学院大学、3.京都大学国際高等教育院)

キーワード：中間圏、乱流エネルギー散逸率、極域中間圏冬季エコー、MSTレーダー

The radar volume reflectivity and turbulent kinetic energy dissipation rate in the Antarctic mesosphere have been estimated from the polar mesosphere winter echoes (PMWE) using a vertical beam of the PANSY radar, which is a Mesosphere-Stratosphere-Troposphere radar, at Syowa Station (69°S, 40°E) over four years. The radar volume reflectivity exhibits a lognormal distribution in the range of 2×10^-18–5×10^-15 m^-1 for a height region of 55–82 km. The turbulent energy dissipation rate estimated from the spectral width of the PMWE ranges from 3×10^-5–3×10^-1 m²s^-3. From monthly histograms of the turbulent energy dissipation rate for a fixed solar zenith angle and altitude, it is revealed that the summer-to-winter transition of the turbulent energy dissipation rate occurs in March, while the winter-to-summer transition occurs in September. This seasonal variation accords well with that of gravity wave activity, suggesting that the turbulence in the mesosphere is likely caused by the gravity wave breaking.