Institute of Atmospheric Physics
大气水汽稳定同位素是现代水循环的重要示踪剂，可以有效地追踪水汽来源及其输送过程。在中低纬度季风区，局地“降水量效应”是大气水汽稳定同位素的主要特征，但是近期研究表明，水汽来源及其输送过程等非局地因素也有重要影响。因此，本文基于拉格朗日粒子扩散模式和卫星遥感观测的大气水汽δD数据，针对前人研究较少的中国东部石笋氧同位素区域，进行水汽源地追踪，并在季节和年际尺度上分析水汽δD的主要影响因素。结果表明，在季节尺度上，水汽δD在夏末秋初较低，冬春季较高，这种特征与局地气象因子、水汽源地贡献的关系较弱，水汽输送路径上的累积降水是影响水汽δD季节变化的主要因素，两者为显著的负相关关系。在年际尺度上，El Ni?o年夏季中国东部水汽δD较高，La Ni?a年夏季水汽δD较低。水汽源地贡献在ENSO不同位相的变化较小，而水汽输送路径上的累积降水在La Ni?a年较之El Ni?o年偏多，表明La Ni?a年热带对流活动和水汽输送过程的贫化作用更强，导致目标区域的水汽δD更低。因此，代表热带对流活动的累积降水是水汽δD季节和年际变化的主要影响因素，热带对流活动增强（减弱）将降低（增加）目标区域的水汽δD。
Stable isotopes in atmospheric water vapor, which can track moisture sources and water vapor transport, are widely used as an important tracer of present-day water cycle. ‘‘Amount effect” is invoked to interpret water vapor stable isotopes at mid-low latitude monsoon region. However, recent studies have shown that non-local factors such as moisture sources and water vapor transport have significant influence on the stable isotopes. Therefore, based on Lagrangian Particle Dispersion Model and Satellite remote sensing δD in water vapor, the main factors affecting water vapor δD are analyzed in the region with abundant Chinese stalagmite δ18O records. On the seasonal scale, water vapor δD is more depleted in late summer and early autumn and enriched in winter and spring. We find this characteristic cannot interpret by "temperature effect" or "amount effect". On the contrary, accumulated rainfall over water vapor transport paths is the dominant factor of water vapor δD and there is a significant negative correlation between them. On the interannual scale, water vapor δD is enriched in the summer of El Ni?o year and depleted in the summer of La Ni?a year. The contribution of moisture sources to water vapor δD is small, but the accumulated rainfall over water vapor transport paths increases significantly in La Ni?a year compared with El Ni?o year. This suggests that tropical convection and depletion in water vapor transport paths are strong in La Ni?a year, resulting in depleted water vapor δD in the study area. In conclusion, upstream convection, measured by accumulated rainfall, is the primary driver of water vapor δD variations on seasonal to interannual scale. Enhanced convection will deplete δD in the study area, while the weakened convection is the opposite.