Water vapor transport to the Tibetan Plateau revealed with stable isotopes of precipitation: a new hypothesis for unusual isotope signals
Abstract
Spatial and temporal variations of oxygen and hydrogen stable isotopes in precipitation were observed on the Tibetan Plateau and in Nepal during the GAME/Tibet field campaign in 1998. Different spatial patterns in delta-18O were found between active and break phases of Indian monsoon activity. During a break phase, low delta-18O with relatively low d-excess (<15_?) values were observed at all observational sites south of Tanggula mountain on the plateau, indicating that water vapor directly transported from the south over the Himalaya reached the central region of the plateau. Decrease in delta-18O from south to north on the plateau was insignificant, which indicates a high contribution of recycled water. During an active phase, low delta-18O with relatively low d-excess was observed in the region between the Himalaya and Nyainqentanghla mountain, indicating direct transport of water vapor from the south to this region, while high delta-18O with high d-excess value was observed in the region between Nyainqentanghla and Tanggula mountains. High delta-18O and high d-excess values were observed when water vapor was transported from the west or north. Water vapor with unusually high delta-18O and high d-excess may be formed by dynamic fractionation of water with low delta-18O in convective clouds in the ITCZ.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2003
- Bibcode:
- 2003AGUFM.A31C0057S
- Keywords:
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- 1655 Water cycles (1836);
- 3309 Climatology (1620);
- 3322 Land/atmosphere interactions;
- 3354 Precipitation (1854)