青藏高原东侧复杂地形区域极端降水的时空演变特征、形成机理及趋势预估研究

由于高大地形和夏季强热源的作用，青藏高原对高原及其周边地区的降水有着重要影响。高原东侧复杂地形区域，中尺度过程和大尺度环流对极端降水的影响更为复杂，其演变特征和形成机理尚待深入研究。本项目拟综合利用多源资料，研究高原东侧复杂地形区域极端降水的时空演变特征，深入认识极端降水对地形的依赖性；揭示复杂地形条件下中尺度过程和大尺度环流对极端降水的多尺度协同影响，阐明其形成机制和协同影响机理；发展适用于复杂地形区域的边界层湍流水平混合参数化方案和复杂云分析技术，提升青藏高原东侧极端降水的模式预报能力；分析比较“第六次耦合模式比较计划”中的全球气候模式的模拟能力，定量评估高原东侧极端降水对气候变化的响应和变化趋势。项目研究成果为深入认识青藏高原东侧极端降水的演变特征、形成机理提供科学基础，提升极端降水的模式预报能力，为川藏铁路等重大工程和“成渝地区双城经济圈”的生态保护和防灾减灾提供科技支撑。

The Tibetan Plateau (TP) has an important influence on precipitation in and around the plateau, due to its giant terrain and strong summertime heat source. The effects of mesoscale processes and large-scale circulation on extreme precipitation are more complex in the complex terrain of the eastern side of TP (CTESTP), where it requires to further study the evolutionary features and formation mechanisms of extreme precipitation. By using multi datasets, this project will investigate the spatial and temporal evolution of extreme precipitation in the CTESTP and understand the dependence of extreme precipitation on the terrain. Furthermore, this project will reveal the multi-scale synergistic effects of mesoscale processes and large-scale circulation on extreme precipitation under complex terrain and its corresponding formation mechanism and mechanism of synergistic impacts. Meanwhile, this project will develop a parameterization scheme of turbulent horizontal mixing in the boundary layer and complex cloud analysis techniques, which are applicable to the complex terrain region. This can enhance the model prediction capability of extreme precipitation over the CTESTP. Finally, this project will compare the simulation capability of global climate models in the Coupled Model Intercomparison Project Phase 6 (CMIP6) and quantitatively assess the response and change trend of extreme precipitation over the CTESTP. The successful implementation of this project will provide a scientific basis to in-depth understand evolutionary characteristics and formation mechanism of extreme precipitation over the CTESTP, enhance the model prediction capability of extreme precipitation, and also provide a scientific support for ecological protection and disaster prevention of major projects such as Sichuan-Tibet railway and “Chengdu-Chongqing Economic Circle”.