Seasonal changes of CO2, CH4, N2O, and SF6 in the upper troposphere/lower stratosphere over the Eurasian continent observed by commercial airliner

The seasonal variations of greenhouse gases at about 11 km altitude were analyzed from monthly air samples collected aboard a commercial airliner flying between Europe and Japan from April 2012 to March 2014. Compared to lower latitudes, the upper troposphere between 50 and 70°N showed higher CH4 an...

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Bibliographic Details
Published in:Geophysical research letters 2015-03, Vol.42 (6), p.2001-2008
Main Authors: Sawa, Yousuke, Machida, Toshinobu, Matsueda, Hidekazu, Niwa, Yosuke, Tsuboi, Kazuhiro, Murayama, Shohei, Morimoto, Shinji, Aoki, Shuji
Format: Article
Language:English
Subjects:
Age
Air pollution
Air sampling
aircraft observation
Altitude
Atmospheric chemistry
Autumn
Carbon dioxide
Flight
Flushing
Flushing (water)
Gases
Greenhouse effect
Greenhouse gases
Lower stratosphere
Meteorology
Methane
Minima
Nitrous oxide
Potential temperature
Seasonal variation
Seasonal variations
Spring
Spring (season)
Stratosphere
Subsidence
Temperature effects
Tropopause
Troposphere
Upper troposphere
UT/LS
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Summary:The seasonal variations of greenhouse gases at about 11 km altitude were analyzed from monthly air samples collected aboard a commercial airliner flying between Europe and Japan from April 2012 to March 2014. Compared to lower latitudes, the upper troposphere between 50 and 70°N showed higher CH4 and SF6 and an earlier seasonal phase of CO2. However, N2O values were similar to those in the subtropics. CH4, N2O, and SF6 in the lower stratosphere with potential temperature of up to 50 K above the tropopause showed seasonal variations with maxima in November/December and minima in April/May. At potential temperatures of 37.5–50 K above the tropopause, SF6 age was estimated to be about 22 months in May and 9 months in November. This strong seasonal variation is explained by the subsidence of high‐stratospheric air in spring and the effective flushing of the lowermost stratospheric air with tropospheric air in autumn. Key Points Higher CH4, SF6 at high latitudes in upper troposphere compared to subtropics Larger seasonal CO2 changes at the high latitudes in the upper troposphere Clear SF6 maximum in autumn in LS from tropospheric influences
ISSN:0094-8276
1944-8007
DOI:10.1002/2014GL062734