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Seasonal changes of CO 2 , CH 4 , N 2 O, and SF 6 in the upper troposphere/lower stratosphere over the Eurasian continent observed by commercial airliner
Author(s) -
Sawa Yousuke,
Machida Toshinobu,
Matsueda Hidekazu,
Niwa Yosuke,
Tsuboi Kazuhiro,
Murayama Shohei,
Morimoto Shinji,
Aoki Shuji
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062734
Subject(s) - stratosphere , troposphere , tropopause , atmospheric sciences , altitude (triangle) , subsidence , latitude , environmental science , seasonality , climatology , subtropics , geology , paleontology , statistics , geometry , mathematics , geodesy , structural basin , fishery , biology
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 CH 4 and SF 6 and an earlier seasonal phase of CO 2. However, N 2 O values were similar to those in the subtropics. CH 4 , N 2 O, and SF 6 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, SF 6 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.