Co-existence of temperature and amount effects on precipitation δ18O in the Asian monsoon region

Abstract

Whether stable oxygen isotope (δ18O) in precipitation obeys the temperature effect and/or amount effect in the monsoon region has long been controversial. An intensive, precipitation event-based sampling project has been carried out at Guangzhou and Changsha stations in southeast China under the Asian monsoon influence. By dividing a year into summer and winter half years at respective station, we find prevalence of amount effect at both stations throughout the year. δ18O-temperature presents complex correlations, with the positive correlation significant at Guangzhou during the summer half year and at Changsha during the winter half year, but vague at either station during the rest of the year; the former attributable to a third mode of convection, while the latter indicative of the weakening monsoon influence accompanied by intensified local recycling. Our high-resolution data demonstrate a significant coexistence of temperature and amount effects of precipitation δ18O in the monsoon domain, conducive to climatic interpretation of δ18O in paleoclimate proxies in mid/low latitudes. © 2011 by the American Geophysical Union.