Variations of tropospheric methane over Japan during 1988–2010

摘要: We present observations of CH 4 concentrations from the lower to upper troposphere (LT and UT) over Japan during 1988–2010 based on aircraft measurements Tohoku University (TU). The analysis is aided by simulation results using an atmospheric chemistry transport model (i.e. ACTM). Tropospheric shows interannual seasonal variations that are dependent altitudes, primarily reflecting differences in air mass origins at different altitudes. long-term trend variation LT consistent with previous reports surface baseline stations northern hemisphere. However, those UT show slightly features LT. In UT, a maximum August due efficient masses influenced continental sources, while reaches its minimum summer enhanced chemical loss. Vertical profiles also vary season, cycles respective summer, -rich Asian regions elevates levels, forming uniform vertical profile above mid-troposphere. On other hand, decreases nearly monotonically altitude winter–spring. ACTM simulations emission scenarios reproduce general tropospheric Japan. Tagged tracer indicate substantial contributions sources South Asia East summertime high values observed UT. This suggests our highly sensitive signals particularly Asia. Keywords: methane, observation, variation, seasonality, profile, outflow, (Published: 22 May 2014) Citation: Tellus B 2014, 66 , 23837, http://dx.doi.org/10.3402/tellusb.v66.23837 To access supplementary material this article, please see Supplementary files under Article Tools online.