Factors controlling spatial and seasonal distributions of precipitation δ 18 O in China

Utilising datasets from the Global Network of Isotopes in Precipitation of the International Atomic Energy Agency, and previous isotopic studies, we investigated δ 18 O spatial and temporal patterns in Chinese precipitation. Significantly positive relationships existed between precipitation δ 18 O and air temperature above the north of 35°N and in high altitude regions above 32°N. Significantly negative relationships between precipitation δ 18 O and the precipitation amount existed below south of 35°N. These temperature and precipitation effects became stronger with increasing altitude except in high altitude regions between 32°N and 35°N. The NCEP/NCAR reanalysis data from 1980 to 2004 showed that variations in spatial and seasonal wind fields at 700 hpa and total precipitable water from the ground to the top of the atmosphere were correlated with the monthly spatial distribution of precipitation δ 18 O. Basing on this relationship, we established quantitative correlations between the mean monthly precipitation δ 18 O and both latitude and temperature in different seasons. We found that spatial variations in precipitation δ 18 O could be described well using the Bowen–Wilkinson model and second‐order equations developed during the present study only in winter (from December to February). During the rest of the year, patterns were too complex to predict using simple models. The results suggest that it is difficult to demonstrate variations of precipitation δ 18 O throughout the year and for all regions of China using a single model. Moreover, the new models for the relationships among precipitation, latitude, and temperature were better able to depict the variations in precipitation δ 18 O than the Bowen–Wilkinson model. Copyright © 2011 John Wiley & Sons, Ltd.