Characteristics of delta18O in precipitation and moisture transports over the arid region in Northwest China
西北干旱区降水中 δ18O变化特征及其水汽输送

Based on the observed data of stable isotopes in precipitation and meteorological statistics at Urümqi (1986-2003), Zhangye (1986-2003), and Hotan (1988-1992) from IAEA/WMO, the precipitation equation of arid region in Northwest China was calculated through the regression analysis, and the characteristics of stable isotopic in precipitation, as well as the correlation between stable isotopic and meteorological records, were analyzed. The water vapor source of the three sites was tracked by the HYSPLIT4. 9 model, and water vapour transmission regime of arid region in Northwest China was established, while the record of delta18O in cryosphere was discussed. Results showed that the precipitation equation of deltaD = 7.24 delta18O + 1.96 per thousand indicates intense evaporation; delta18O values at Urümqi, Zhangye and Hotan fluctuates at -20.58 per thousand- -5.4 per thousand, -18.58 per thousand- -2.46 per thousand and -20.33 per thousand- -0.01 per thousand, respectively. The delta18O value is low in winter and high in summer, but the values of d-excess is on the contrary; The spatial distribution shows that delta18O value at Zhangye is highest, followed by Hotan, and the lowest is at Urümqi; The highest of d-excess value is at Urümqi, followed by Hotan, the lowest is at Zhangye; The temperature effect of delta18O in precipitation is significant with the correlation coefficients of 0.85, 0.81 and 0.86, respectively, and the rainfall effect does not exist; The modeled trajectory of vapor source showed there are two main paths all the year, which are from the Atlantic Ocean via Westerlies and the Arctic region, respectively, influence by different vapor sources, the seasonality of delta18O values lower in winter, higher in summer; In addition, according to the cryospheric environment, the correlation between delta18O in snow pack or ice core and the corresponding meteorological station record was significant, which reflects the variation of temperature efficiently.