西风水汽源区与传输路径变化对亚洲中部干旱区的水循环有深远影响。氢氧稳定同位素是水循环的天然示踪剂，但是西风水汽传输过程对亚洲内陆大气水汽与降水同位素的影响机制仍不明确。本项目拟以新疆北部额尔齐斯河谷为重点开展大气水汽氢氧稳定同位素的实地监测，结合同位素大气环流模式的模拟结果，揭示天气尺度、季节尺度和年际尺度下西风控制区水汽传输过程对水汽同位素的影响；明确沿河谷水汽通道的降水氢氧稳定同位素演化过程，分析云下蒸发和水汽再循环等因素的影响；探明干旱气候下水汽同位素和降水同位素的联系，并建立区域水循环中的氢氧稳定同位素分馏过程模型。项目旨在深入认识西风控制区大气水汽和降水氢氧稳定同位素的演化机理，为冰芯氢氧稳定同位素记录的解释提供参考，并有助于深入理解西风水汽输送对亚洲中部干旱区陆－气相互作用和水文循环的影响过程。

The regional water cycle across arid central Asia is greatly influenced by the westerly moisture source and trajectory. Although the stable isotopes are widely applied as a natural tracer in hydrological processes, it is still debatable how the moisture transport controls stable isotopes in water vapor and precipitation across this westerly-dominated area. In this proposal, the Ertix River valley in northern Xinjiang is selected as a study region. To investigate the role of westerly moisture transport on synoptic, seasonal and annual scales, the stable hydrogen and oxygen isotopes in near-surface water vapor will be continually measured using a laser-based water vapor isotope analyzer, and the simulations of isotope-enabled general circulation models will also be involved. Based on the precipitation samples collected along the river valley, the evolution of stable isotopes in precipitation as well as the controlling factors (especially below-cloud evaporation and moisture recycling) are analyzed. The connection of stable isotopes in water vapor and precipitation in an arid setting can be studied, and a model of isotopic fractionation in regional water cycle will be established. This program will be useful to understand the influencing regimes of stable water isotopes in arid central Asia as well as the isotopic records in ice cores, and will provide important information how the westerly moisture impacts the land-atmosphere interaction and hydrological cycle in arid central Asia.