水汽源区变化对黄河中游降水稳定同位素的影响

Effect of Variation in Water Source Area on Stable Isotopes in Precipitation in the Middle Reach of the Yellow River Basin

利用黄河中游地区9个站点的降水同位素数据,分析其时空分布特征及环境效应,并模拟代表站点的气团运移轨迹,利用OLR技术研究水汽源区变化及输送过程对夏半年降水稳定同位素的影响。结果表明:δ18O有着较为明显的季节性变化规律,春夏较低,秋冬较高;空间分布则呈由东南向西北升高的趋势。大气降水线方程表现出明显的过渡性区位特征,降水量效应较为显著。水汽主要通过西北与东南两个水汽通道输送,东向水汽与青藏高原的热力、动力性质对流域的水源差异产生了较大影响。水汽源区变化与对流层中上部水汽含量场都与稳定同位素特征有着较强的对应关系,8、9月形成于西太平洋的热带辐合带(ITCZ)使东南季风成为夏季黄河中游地区主要的水汽输送通道。

Using the precipitation isotope data observed at nine stations in the middle reach of the Yellow River Basin,the spatial and temporal distribution characteristics and environmental effect of isotope in precipitation are analyzed,the trajectories of air mass transport in this area are simulated,and the changes of the water source area and the influence of conveying process on stable isotopes in precipitation in summer half year are studied by using OLR technology. The result shows:the content of δ18O precipitation has obvious seasonal variation that it is lower in spring and summer and higher in autumn and winter;the content of δ18O in precipitation increases from southeast to northwest;the meteoric water line shows obvious transitional features,and the precipitation effect is relatively significant;the water vapor source is transported mainly through the two channels:the northwest and southeast.The water vapor from east and the thermal and dynamic properties of the Tibetan Plateau have a great influence on the sources of water vapor in the basin.The change of water vapor source region and water vapor content field in the upper and middle 'troposphere have good relationship with the characteristics of stable isotope.In August and September,ITCZ formed in the western Pacific makes the southeast monsoon the main water vapor channel in summer in the middle reach of the Yellow River Basin.