基于水汽氢氧稳定同位素协同监测的水汽再循环模型不确定性评估与改进

再循环水汽对陆地降水有重要贡献，定量评估局地水汽再循环是生态水文领域的前沿话题。氢氧稳定同位素技术被广泛用于局地水汽再循环比评估，可求解外来水汽、蒸发水汽和蒸腾水汽混合比例，然而限于野外监测手段，对模型不确定性尚缺乏足够的认识。本项目拟在中国气象局兰州干旱气象研究所定西干旱气象与生态环境试验基地开展大气水汽和降水同位素定位监测，明确不同时间尺度下水汽与降水同位素的联系；在周边区域利用便携式水汽同位素分析仪开展短期动态监测，通过对比水汽同位素实时记录从而认识水汽输送过程；基于上下风向水汽同位素协同监测，结合定西基地蒸散发等资料，评估蒸腾和蒸发对局地降水的贡献率，认识水汽再循环模型的不确定性，并提出算法推荐方案。项目旨在深入认识基于氢氧稳定同位素技术的水汽再循环模型不确定性，提高模型模拟精度，为黄土高原西部半干旱气候陆面过程与陆气相互作用研究做出贡献。

The recycled moisture plays an important role in terrestrial precipitation. It is a hot topic in ecological hydrology to quantificationally assess the local moisture recycling. The stable hydrogen and oxygen isotope technique has been widely applied in assessment of moisture recycling ratio, and the proportional contributions for advection, evaporation and transpiration can be determined respectively. However, because of the field measurement, there is no enough knowledge about the uncertainty of isotopic model. In this proposal, the Dingxi Experiment Base of Arid Meteorology and Ecological Environment (Institute of Arid Meteorology, China Meteorological Administration, Lanzhou) is selected as an in-situ station to measure stable hydrogen and oxygen isotopes in water vapor and precipitation, which is useful to understand the relationship between stable isotopes in water vapor and precipitation for different temporal scales. An ultra-portal analyzer of water vapor isotopes will be applied at surrounding areas, and the moisture transport process can be determined using the isotopic records in water vapor at different locations. Based on the water vapor measurement at the upwind and target stations as well as other measurements at the Dingxi Experiment Base like evapotranspiration, the contribution of transpiration and evaporation to local precipitation and the uncertainty can be assessed, and the optimal parameterization for critical parameters will be recommended. This research aims to understand the uncertainty of moisture recycling model using stable hydrogen and oxygen isotope technique, which is useful to improve the accuracy of simulation. This finding is of great significance to understand the land surface processes as well as land-atmosphere interactions in a semi-arid climate at the western Loess Plateau.