A model-based determination of spatial variation of precipitation δ18O over China

Many works show the dependence of precipitation 6180 on altitude and latitude as a result of air temperature change. The assumption that these quantitative relations can hold across a large geographical region can be used to give a rough estimation of local precipitation delta O-18 where there is on direct observation of precipitation delta O-18. Although there truly exists uncertainty in the estimation, an effect was made in this paper to establish the precipitation 6180 pattern over the whole China. Based on regional topography and the delta O-18 of meteoric precipitation, this paper established a quantitative relationship between delta O-18 in precipitation and latitude and altitude using the existing 6180 data from 55 sites over China. The model describes as delta O-18(ppt)=-0.0073LAT2+0.3261LAT-0.0015ALT-9.7776, and was used to generate a higher-resolution map of mean annual 6180 for precipitation over China using geographic information system software, integrating with latitude, altitude and the moisture cycle. This determination of the spatial distribution of 6180 in modem precipitation of China provides important information for ancient climate and stable isotope hydrology studies. (C) 2007 Elsevier B.V. All rights reserved.