[A-AS09] [EE] 成層圏－対流圏相互作用　―統一領域としての新しい視点―

[AAS09-P09] Seasonal variations and trends of greenhouse gases in the upper troposphere/lowermost stratosphere by flask-based aircraft measurements between Europe and Japan

*澤 庸介¹、町田 敏暢²、松枝 秀和¹、丹羽 洋介¹、坪井 一寛¹、勝又 啓一²、梅澤 拓²、江藤 仁樹³、藤田 遼⁴、後藤 大輔⁵、森本 真司⁴、青木 周司⁴ (1.気象研究所海洋・地球化学研究部、2.国立環境研究所、3.日本航空株式会社、4.東北大学、5.国立極地研究所)

キーワード：Greenhouse gases, Upper troposphere/Lower Stratosphere, Aircraft measurement

As part of the CONTRAIL project, we have conducted measurements of greenhouse gases (CO₂, CH₄, N₂O, and SF₆) by monthly air sampling in the upper troposphere/lowermost stratosphere (UT/LMS) onboard commercial airliners between Europe and Japan since April 2012. The observed mixing ratios showed sharp gradients around the dynamical tropopause defined by potential vorticity calculated from the meteorological reanalysis fields. In the UT north of 50 N, CH₄ and SF₆ were higher and seasonal phase of CO₂ were earlier than in the lower latitudes. In the LMS up to potential temperature of 50 K above the tropopause, CH₄, N₂O, and SF₆ exhibited seasonal variations with maxima in November/December and minima in April/May. The remarkable seasonal variation in the LMS is explained by the subsidence of air from the deeper stratosphere in spring and by the efficient flushing of the LMS with tropospheric air in autumn. We observed persistent increasing trends of the all greenhouse gases over the past 5 years both in the UT and LMS. Our measurements constitute a unique data set in the UT/LMS useful for investigating temporal and spatial variations of these radiatively and chemically important greenhouse gases.