Stable isotopes of summer monsoonal precipitation in southern China and the moisture sources evidence from δ18O signature

Summer monsoons (South Asian monsoon, South China Sea monsoon and Subtropical monsoon) are prominent features of summertime climate over southern China. Different monsoons carry different inflow moisture into China and control the temporal and spatial distributions of precipitation. Analyses of meteorological data, particularly wind, temperature and pressure anomalies are traditional methods of characterizing moisture sources and transport patterns. Here, we try to utilize the evidence from stable isotopes signatures to trace summer monsoons over southern China. Based on seven CHNIP (Chinese Network of Isotopes in Precipitation) observatory stations located in southern China, monthly composite precipitation samples have been collected and analyzed for the composition of delta O-18 during July, 2005. The results indicated that the spatial distributions of delta O-18 in precipitation could properly portray the moisture sources together with their transport pathways. Moreover, the amount effect, altitude effect, temperature effect and the correlation between delta O-18 vs. relative humidity were discussed.