HR: 0800h
AN: C51B-1043 [Abstracts]
TI: The isotopic composition of water vapor and the concurrent
Atmospheric circulations around Qilian Mountains in the
northeast part of the Tibetan Plateau
AU: Yatagai, A
EM: akiyo@chikyu.ac.jp
AF: Research Institute for Humanity and Nature, Takashima-cho, Kamigyo-ku, Kyoto, 602-0878
Japan
AU: * Sugimoto, A
EM: sugimoto@star.dti2.ne.jp
AF: Graduate School of Environmental Earth Science, Kita 10, Nishi 5, Sapporo, 060-0810
Japan
AU: Nakawo, M
EM: nakawo@chikyu.ac.jp
AF: Research Institute for Humanity and Nature, Takashima-cho, Kamigyo-ku, Kyoto, 602-0878
Japan
AB:
The stable isotopic ratio of water vapor (d18O and dD) was measured near July-1st (Qiyi) Glacier (39.25N, 97.75E, 4250 m) in
Northwest China. From 11 to 17 August 2003, we collected and then analyzed atmospheric samples at July-1st Glacier and a base
camp (BC), that was 4km from Qiyi. Then the temporal change of the isotopic composition was compared with the atmospheric
circulation fields using and European Centre for Medium-range Weather Forecasts (ECMWF) objective analysis dataset.
After a snowfall in the early afternoon of the 14th, a strong northerly wind was observed in the evening. The isotopic
analysis revealed a clear difference in the evening of 14th, which showed lighter dD (and d18O ) and much higher d-excess
compared with those of the previous period. The snowfall and the strong northerly wind that followed were identified with the
passing of a deep trough with a cold front that was observed at 500 hPa and dry air from the northwest. A back trajectory
analysis revealed that the dry air from the northwest came from the upper troposphere/lower stratosphere.
We also found a diurnal change in the isotopic composition. These results suggest that air from the Tibetan Plateau has
relatively high d18O and dD values and relatively low d-excess values, while, the air from the northern desert has relatively
small d18O, relatively small dD values and relatively high d-excess values.
DE: 3322 Land/atmosphere interactions
DE: 1854 Precipitation (3354)
DE: 1866 Soil moisture
DE: 1040 Isotopic composition/chemistry
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting