Climatological significance of δ18 O in precipitation and ice cores: a case study at the head of the Ürümqi river, Tien Shan, China

• Published in: Journal of Glaciology
• Main Authors: Shugui, Hou, Dahe, Qin, Mayewski, Paul A., Qinzhao, Yang, Jiawen, Ren, Zhongqin, Li, Cunde, Xiao
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1999
• Subjects: Earth-Surface Processes; ice core; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000001374; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001374

Abstract Stable-oxygen-isotope ratios (δ 18 O) of precipitation and ice-core samples collected from the headwaters of the Urümqi river, Tien Shan, China, were used to test the relationship between δ 18 O and contemporaneous surface air temperature (T a ). A strong temporal relationship is found between δ 18 O in precipitation and T a , particularly for the monthly averages which remove synoptic-scale influences such as changes in condensation level, condensation temperature and moisture sources ( Yao and others, 1996). Linear fits as high as 0.95‰° C -1 for precipitation events and 1.23‰° C -1 for monthly averages are found. Although the δ 18 O amplitude in ice cores drilled at the nearby Ürümqi glacier No.1(~2 km from the precipitation sampling site) decreased dramatically compared to the precipitation samples, the ice-core records of annually averaged δ 18 are still positively correlated with contemporaneous air temperature, especially summer air temperature, at the nearby Daxigou meteorological station. Nevertheless, the relationship between the ice-core δ 18 O records and contemporaneous air temperature is less significant than that for the precipitation samples due to depositional and post-depositional modification processes, which are highlighted by the successive snow-pit δ 18 O profiles from the Ürümqi glacier No.1. Our results might extend the application of high-altitude and subtropical ice-core δ 18 O — T a records for paleoclimate reconstruction.