HR: 0800h
AN: C51B-1040    [Abstracts]
TI: Variations of d18O in Precipitation Along Different Vapor Transport Paths of Asia
AU: Zhang, X
EM: zxp@hunnu.edu.cn
AF: College of Resources and Environment Sciences, Hunan Normal University, Lushan South Road, West Region,, Changsha, Hun 410081 China
AU: * Yang, D
EM: ffdy@uaf.edu
AF: Water and Environmental Research Center, Univ. of Alaska Fairbanks, University of Alaska Fairbanks , Fairbanks, AK 99775-5860 United States
AB: Three sampling cross-sections along the south path starting from the tropics through the vapor passage in Yunnan-Guizhou Plateau to the middle-low reaches of Yangtze River, the north path from west China, via north China, to Japan under the westerlies and the plateau path from South Asia over the Himalayas to the northern Tibetan Plateau, are set up, based on the IAEA/WMO global survey network and sampling sites on the Tibetan Plateau. The variations, and the relationship with precipitation and temperature, of the d18O in precipitation along the three cross-sections are analyzed and compared. Along the south path, the seasonal differences of mean d18O in precipitation are small at the stations located in tropics, but increase markedly from Bangkok towards the north, with the d18O in the rainy season smaller than that in the dry season. The d18O values in precipitation fluctuate on the whole, which shows that the different vapor sources. Along the north path, the seasonal differences of the mean d18O in precipitation for the stations in the west of Zhengzhou are all greater than that in the east of Zhengzhou. During the cold half-year, the mean d18O in precipitation reaches its minimum in Urumqi with the lowest temperature owing to the wide Cold-High Pressure over the Mongolia, then increases gradually with longitude, and keeps at a roughly same level at the stations eastward from Zhengzhou. During the warm half-year, the d18O values in precipitation are lower in the east than in the west, influencing by the summer monsoon over East Asia markedly. Along the plateau path, the mean d18O values in precipitation in the rainy season are correspondingly high in the south parts of the India Subcontinent, and then decrease gradually with latitude. A sharp depletion of the stable isotopic compositions in precipitation takes place due to the very strong rainout of the stable isotopic compositions in vapor in the process of the lifting on the southern slope of the Himalayas. The low level of the d18O in precipitation is from Nyalam to the Tanggula Mountains during the rainy season all the while, but d18O increases with increasing latitude persistently from the Tanggula Mountains to the northern Tibetan Plateau because of the replenishment of vapor with the relative heavy stable isotopic compositions originating from the inner Plateau. During the dry season, the mean d18O values in precipitation decrease basically along the path from the south to the north. Generally, the mean d18O in precipitation during the rainy season are lower than those in the dry season for the regions controlled by the monsoons over South Asia or the Plateau, on the contrary for the regions without monsoon or by weak monsoon. Key words: stable isotope; vapor transport path; temperature; precipitation
DE: 1655 Water cycles (1836)
DE: 1854 Precipitation (3354)
DE: 1040 Isotopic composition/chemistry
DE: 1065 Trace elements (3670)
DE: 1600 GLOBAL CHANGE (New category)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting