[A-AS05] 成層圏・対流圏過程とその気候への影響

[AAS05-05] Transport of trace gases into the extratropical upper troposphere/lower stratosphere

★Invited Papers

*稲飯 洋一¹、藤田 遼^2,1、町田 敏暢³、松枝 秀和⁴、澤 庸介⁴、坪井 一寛⁴、勝又 啓一^3,5、森本 真司¹、青木 周司¹、中澤 高清¹ (1.東北大学、2.Imperial College London、3.環境研、4.気象研、5.高千穂化学工業)

キーワード：物質輸送、地球大気、流跡線解析

To investigate the seasonal characteristics of chemical tracer distributions in the extratropical upper troposphere and lower stratosphere (ExUTLS) as well as stratosphere–troposphere exchange processes, origin fractions of air masses originating in the stratosphere, tropical troposphere, mid-latitude lower troposphere (LT), and high-latitude LT in the ExUTLS are estimated using 10-year backward trajectories calculated with European Centre For Medium-Range Weather Forecasts (ECMWF) ERA-Interim data as the meteorological input. Time-series of chemical tracers obtained from ground-based and airborne observations are incorporated into the trajectories, thus reconstructing spatiotemporal distributions of chemical tracers in the ExUTLS. The reconstructed tracer distributions are analysed with the origin fractions and the stratospheric age of air (AoA) estimated using the same backward trajectory. The reconstructed distributions of CO and CO₂ in the ExUTLS are affected primarily by tropospheric air masses because of the short chemical lifetime of the former and large seasonal variations in the troposphere of the latter. Distributions of CH₄, N₂O, and SF₆ are controlled primarily by seasonally varying air masses transported from the stratosphere. For CH₄ and N₂O distributions, their seasonally varying photochemical decay along the average pathway from the source region are particularly important. This study developed and demonstrated a unique and effective method to exploit the advantages of observational data in combination with trajectory analysis. This method provides a means to understand both air mass transport and chemical decay for photochemical active substances from a new perspective.