HR: 14:40h
AN: A23E-05    [Abstracts]
TI: Long-Term Observation of Atmospheric Molecular Hydrogen Using Aircrafts
AU: * Machida, T
EM: tmachida@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Watai, T
EM: watai.tomonori@nies.go.jp
AF: Global Environmental Forum, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Tohjima, Y
EM: tohjima@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Arshinov, M
EM: michael@iao.tsc.ru
AF: Institute of Atmospheric Optics SB RAS, Akademicheskii av.1, Tomsk, 634055 Russian Federation
AU: Fedoseev, N
EM: fedoseev@mpi.ysn.ru
AF: Permafrost Institute SB RAS, 10, Yakutsk, 677018 Russian Federation
AU: Yazawa, K
AF: Japan Aerospace Exploration Agency, 6-13-1 Osawa, Mitaka, 181-0015 Japan
AU: Inagaki, T
EM: inagaki@asuka.nal.go.jp
AF: Japan Aerospace Exploration Agency, 6-13-1 Osawa, Mitaka, 181-0015 Japan
AU: Inoue, G
EM: inouegen@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AB: Temporal and spatial variations of atmospheric molecular hydrogen (H$_{2}$) are observed using aircrafts over Novosibirsk ($55\deg$N, $83\deg$E), West Siberia, Yakutsk ($62\deg$N, $130\deg$E), East Siberia and Sagami-bay ($35\deg$N, $139\deg$E), Japan since 1997. H$_{2}$ mixing ratios in air samples collected in Pylex flasks are measured using a gas chromatograph (HP5890, Agilent Technologies) equipped with Reduction Gas Detector (RGD-2, Trace Analytical). Primary standard gases with their mixing ratios of 400, 500, 600 and 700 ppb were prepared by gravimetric method. Four working standard gases, ranging from 420 to 630 ppb, are calibrated by primary standard approximately once per year. Atmospheric H$_{2}$ mixing ratios observed in this study show clear seasonal variation with their maximum in spring or summer and minimum in late autumn or early winter. The phase of the seasonal change in lower troposphere is 1-3 months earlier than that in upper troposphere. Peak-to-peak amplitude at 1km over Novosibirsk is 40 ppb, while that at 7km is 23 ppb. In Siberia, the largest gradient in H$_{2}$ mixing ratio, with lower values in lower altitude, is observed in early winter when seasonal variation at lower troposphere indicates minimum. On the other hand, atmospheric H$_{2}$ is almost constant along the altitude in spring when lower tropospheric H$_{2}$ shows maximum. Vertical profile of annual mean H$_{2}$ mixing ratio over Siberia shows negative gradient in each observed year, indicating substantial amount of H$_{2}$ is removed by soil deposition in the continental interior. While over Japan, positive gradient is observed in the annual mean H$_{2}$ at the altitudes lower than 2km, suggesting H$_{2}$ emission by fossil fuel combustion enhance atmospheric mixing ratio near the surface.
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting