长江流域大气降水中δ^(18)O变化与水汽来源

Variations of δ^(18)O in precipitation and moisture sources in the Yangtze River Basin

根据GNIP所提供的长江流域多年月平均降水中δD、δ18O资料以及NOAA-CIRES提供的NCEP/NCAR再分析资料,研究了长江流域降水稳定同位素与降水量、水汽压、温度和水汽来源之间的关系。结果表明:在平均季节尺度下,长江流域大气降水中δ18O与降水量、水汽压和温度均存在显著的负相关关系,说明该流域降水中δ18O变化存在显著的降水量效应、湿度效应和反温度效应。基于降水中过量氘示踪水汽来源原理,分析了中国长江流域季风区降水中过量氘与阿拉伯海、孟加拉湾和南印度洋3个海区相对湿度的关系,表明中国长江流域的水汽主要来源于上述3个海区,而昆明和成都可能受到其他水汽作用,使其与水汽源区的相对湿度呈正相变化。

Based on the monthly mean δD and δ^18Odata in precipitation in the Yangtze River Basin from GNIP and the NCEP/NCAR reanalysis data from the NOAA-CIRES,the relationships between stable isotopes in precipitation and precipitation amount,air pressure,temperature,moisture sources were analyzed in the Yangtze River Basin.The results indicate that the δ^18Oin precipitation is in the negative correlations with precipitation amount,air pressure and temperature in the Yangtze River Basin under the seasonal scale,and it suggests that the variations of δ^18Oin precipitation are of significant precipitation amount effect,humidity effect and anti-temperature effect.According to the principle exploring the moisture sources by deuterium excess in precipitation,the relationships between deuterium excess in precipitation and relative humidity in the Arabian Sea,the Bay of Bengal and the South Indian Ocean are analyzed,which suggests that the vapor mainly originates from three above-mentioned sea regions.However,deuterium excess in precipitation is in a positive phase relationship with the relative humidity of moisture sources areas in Kunming and Chengdu stations,which may be affected by other vapor sources.