Oxygen-18 concentrations in recent precipitation and ice cores on the Tibetan Plateau

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Read Full Article (file size: 3969319 bytes) Cited by JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D9, 4293, doi:10.1029/2002JD002173, 2003 Oxygen-18 concentrations in recent precipitation and ice cores on the Tibetan Plateau L. Tian Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China Institute of Tibetan Plateau Research, Beijing, China Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA T. Yao Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China Institute of Tibetan Plateau Research, Beijing, China P. F. Schuster U.S. Geological Survey, Boulder, Colorado, USA J. W. C. White Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA K. Ichiyanagi Institute for Global Change Research, Yokohama, Japan E. Pendall Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA J. Pu Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China W. Yu Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China Abstract A detailed study of the climatic significance of δ¹⁸O in precipitation was completed on a 1500 km southwest-northeast transect of the Tibetan Plateau in central Asia. Precipitation samples were collected at four meteorological stations for up to 9 years. This study shows that the gradual impact of monsoon precipitation affects the spatial variation of δ¹⁸O-T relationship along the transect. Strong monsoon activity in the southern Tibetan Plateau results in high precipitation rates and more depleted heavy isotopes. This depletion mechanism is described as a precipitation “amount effect” and results in a poor δ¹⁸O-T relationship at both seasonal and annual scales. In the middle of the Tibetan Plateau, the effects of the monsoon are diminished but continue to cause a reduced correlation of δ¹⁸O and temperature at the annual scale. At the monthly scale, however, a significant δ¹⁸O-T relationship does exist. To the north of the Tibetan Plateau beyond the extent of the effects of monsoon precipitation, δ¹⁸O in precipitation shows a strong temperature dependence. δ¹⁸O records from two shallow ice cores and historic air temperature data were compared to verify the modern δ¹⁸O-T relationship. δ¹⁸O in Dunde ice core was positively correlated with air temperature from a nearby meteorological station in the north of the plateau. The δ¹⁸O variation in an ice core from the southern Plateau, however, was inversely correlated with precipitation amount at a nearby meteorological station and also the accumulation record in the ice core. The long-term variation of δ¹⁸O in the ice core record in the monsoon regions of the southern Tibetan Plateau suggest past monsoon seasons were probably more expansive. It is still unclear, however, how changes in large-scale atmosphere circulation might influence summer monsoon precipitation on the Tibetan Plateau. Published 13 May 2003. Index Terms: 1040 Geochemistry: Isotopic composition/chemistry; 1620 Global Change: Climate dynamics (3309); 1655 Global Change: Water cycles (1836). Read Full Article (file size: 3969319 bytes) Cited by Citation: Tian, L., T. Yao, P. F. Schuster, J. W. C. White, K. Ichiyanagi, E. Pendall, J. Pu, and W. Yu (2003), Oxygen-18 concentrations in recent precipitation and ice cores on the Tibetan Plateau, J. Geophys. Res., 108(D9), 4293, doi:10.1029/2002JD002173. Copyright 2003 by the American Geophysical Union.

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