气候变暖直接影响区域水循环变化和水系统稳定性，引起河川径流补给方式和水文过程改变，加大水资源不确定性。天山被誉为“中亚水塔”，对中亚干旱区自然环境和绿洲生存发展具有重要影响，是当今地球系统科学研究的热点地区。在全球变暖背景下，天山山区降水的变异性加大，降雪率改变。而山区降雪率的改变不仅影响冰川的积累、消融过程，而且显著影响山区水文过程和水资源变化。本项研究针对该区观测资料稀缺、水循环过程复杂及水资源对气候变化极度敏感的特点，拟通过加密降水观测获得高精度的单点降水（雨/雪）数据，结合多源数据分析方法和同化技术，开展高精度的降雪、降水量观测和资料校正；辨析天山山区降雪率变化趋势、空间分异特征；阐明降雪率变化时空差异产生的根源、机理及对气候变化的响应关系；解析降雪率变化对山区产汇流变化的影响程度以及河川径流对降雪率变化的敏感性。研究成果对科学管理水资源、服务于国家丝绸之路经济带建设具有重要意义。

Global warming directly affects the regional water cycle and water system stability, alters the supply patterns and hydrologic processes of streamflow, and intensifies water resources uncertainty. Tienshan Mountains, with the status of "water tower in Central Asia", has important role of the natural environment and oasis development in the arid region of Central Asia. It is becoming the hot spots in the earth system sciences research. On the context of global warming, the variability of precipitation increases, causing a higher fraction of precipitation falling as snow in the Tienshan Mountains. A shift from snow towards rain dominated regime is currently assumed not only influence the accumulation and ablation of glaciers, but also influence the mean streamflow and water resources significantly. Due to the sparse hydrometeorological station network in the cold highland mountains, there is critical shortage in hydrological and meteorological data. Based on the characteristics of the unique water cycle and a strong sensitivity to climate change in the Tienshan Mountains, this project intends to increase the automatic rain gauges to getting high-resolution precipitation (rainfall and snowfall) data. Combined the multi-source data analysis and assimilation technology, this project obtains a high-precision precipitation database, analyses the change trend, spatial differentiation characteristics of snowfall fraction, clarifies the influence mechanism of snowfall fraction change and its response to climate change, and reveals the sensitivity of streamflow to snowfall fraction change. This understanding will then lay a scientific basis for the water resources management in Central Asia and silk road economic belt construction.