TY - JOUR
T1 - Temporal Characteristics of CH4 Vertical Profiles Observed in the West Siberian Lowland Over Surgut From 1993 to 2015 and Novosibirsk From 1997 to 2015
AU - Sasakawa, M.
AU - Machida, T.
AU - Ishijima, K.
AU - Arshinov, M.
AU - Patra, P. K.
AU - Ito, A.
AU - Aoki, S.
AU - Petrov, V.
N1 - Funding Information:
We thank Sergey Mitin (Institute of Microbiology, Russian Academy of Sciences) for administrative support. The authors thank the staff of the Zuev Institute of Atmospheric Optics, Russia and the Winogradsky Institute of Microbiology, Russia for supporting the air sampling over Siberia. This research was supported by a fund for global environmental monitoring by CGER, NIES. The used data are available from the Global Environmental Database, hosted by CGER, NIES (http://db.cger. nies.go.jp/portal/geds/index).
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/10/27
Y1 - 2017/10/27
N2 - We have carried out monthly flask sampling using aircraft, in the altitude range of 0–7 km, over the boreal wetlands in Surgut (61°N, 73°E; since 1993) and a pine forest near Novosibirsk (55°N, 83°E; since 1997), both located in the West Siberian Lowland (WSL). The temporal variation of methane (CH4) concentrations at all altitudes at both sites exhibited an increasing trend with stagnation during 2000–2006 as observed globally from ground-based networks. In addition to a winter maximum as seen at other remote sites in northern middle to high latitudes, another seasonal maximum was also observed in summer, particularly in the lower altitudes over the WSL, which could be attributed to emissions from the wetlands. Our measurements suggest that the vertical gradient at Surgut has been decreasing; the mean CH4 difference between 5.5 km and 1.0 km changed from 64 ± 5 ppb during 1995–1999 to 37 ± 3 ppb during 2009–2013 (mean ± standard error). No clear decline in the CH4 vertical gradient appeared at Novosibirsk. Simulations using an atmospheric chemistry-transport model captured the observed decrease in the vertical CH4 gradient at Surgut when CH4 emissions from Europe decreased but increased from the regions south of Siberia, for example, East and South Asia. At Novosibirsk, the influence of the European emissions was relatively small. Our results also suggest that the regional emissions around the WSL did not change significantly over the period of our observations.
AB - We have carried out monthly flask sampling using aircraft, in the altitude range of 0–7 km, over the boreal wetlands in Surgut (61°N, 73°E; since 1993) and a pine forest near Novosibirsk (55°N, 83°E; since 1997), both located in the West Siberian Lowland (WSL). The temporal variation of methane (CH4) concentrations at all altitudes at both sites exhibited an increasing trend with stagnation during 2000–2006 as observed globally from ground-based networks. In addition to a winter maximum as seen at other remote sites in northern middle to high latitudes, another seasonal maximum was also observed in summer, particularly in the lower altitudes over the WSL, which could be attributed to emissions from the wetlands. Our measurements suggest that the vertical gradient at Surgut has been decreasing; the mean CH4 difference between 5.5 km and 1.0 km changed from 64 ± 5 ppb during 1995–1999 to 37 ± 3 ppb during 2009–2013 (mean ± standard error). No clear decline in the CH4 vertical gradient appeared at Novosibirsk. Simulations using an atmospheric chemistry-transport model captured the observed decrease in the vertical CH4 gradient at Surgut when CH4 emissions from Europe decreased but increased from the regions south of Siberia, for example, East and South Asia. At Novosibirsk, the influence of the European emissions was relatively small. Our results also suggest that the regional emissions around the WSL did not change significantly over the period of our observations.
KW - West Siberian Lowland
KW - aircraft observation
KW - methane
KW - nitrous oxide
KW - vertical profile
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U2 - 10.1002/2017JD026836
DO - 10.1002/2017JD026836
M3 - Article
AN - SCOPUS:85038028067
VL - 122
SP - 11,261-11,273
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 2169-897X
IS - 20
ER -