Seasonal characteristics of trace gas transport into the extratropical upper troposphere and lower stratosphere

Yoichi Inai, Ryo Fujita, Toshinobu Machida, Hidekazu Matsueda, Yousuke Sawa, Kazuhiro Tsuboi, Keiichi Katsumata, Shinji Morimoto, Shuji Aoki, Takakiyo Nakazawa

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


To investigate the seasonal characteristics of trace gas 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, midlatitude 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 trace gases obtained from ground-based and airborne observations are incorporated into the trajectories, thus reconstructing spatiotemporal distributions of trace gases in the ExUTLS. The reconstructed tracer distributions are analyzed with the origin fractions and the stratospheric age of air (AoA) estimated using the backward trajectories. The reconstructed distributions of SF6 and CO2 in the ExUTLS are linearly correlated with those of AoA because of their chemically passive behavior and quasi-stable increasing trends in the troposphere. Distributions of CH4, N2O, and CO are controlled primarily by chemical decay along the transport path from the source region via the stratosphere and subsequent mixing of such stratospheric air masses with tropospheric air masses in the ExUTLS.

Original languageEnglish
Pages (from-to)7073-7103
Number of pages31
JournalAtmospheric Chemistry and Physics
Issue number10
Publication statusPublished - 2019 May 27

ASJC Scopus subject areas

  • Atmospheric Science


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