A tentative study of the relationship between annual δ18O & δD variations of precipitation and atmospheric circulations—A case from Southwest China

Abstract

In this study, we present the 6-year δ18O and δD records of precipitation from Chongqing, southwest China. Based on these data, the local meteoric water line (LMWL) has been set up as: δD = 8.33δ18O+19.42. It is demonstrated that in El Niño scenarios, more vapor from closer moisture source (Western Pacific) was transported to south China, resulted in heavier stable isotopes of precipitation in southwest China, while in La Niña scenarios, the situations were just on the contrary. In addition, there is a positive correlation between the δ18O of precipitation in southwest China and the Northern Atlantic Oscillation Index (NAOI) when the NAO is in the positive phase (typically in boreal winter-half year). At the interannual timescale, the δ18O of precipitation in southwest China is more negative in strong NAO years than that in weak NAO years. We speculate that the north-south position migration of the westerlies and the route changes of vapor transport are correlated with the δ18O changes of precipitation in southwest China under the climate change scenario around the North Atlantic.