青藏高原云降水物理及其对能量收支和水分循环的影响

Till right now, the processes of cloud and precipitation physics in the Tibet Plateau is not truly understood. It seriously affects the objectivity of these processes described by weather model. Based on previous achievements, especially on the basis of detection data, this proposal will establish a comprehensive dataset in multiple temporal-spatial scales with integrating cloud parameters, precipitation, latent heat and atmospheric parameters in the Tibet Plateau in terms of multi-source detections from satellite platforms, ground bases and reanalysis datasets. Through the analysis on this comprehensive dataset, the spatial and temporal variations of macro and micro parameters of cloud and precipitation associated with synoptic system changes over the Tibetan Plateau are going to be investigated to perceive natures of cloud parameters, precipitation types and their intensity as well as the relationship among them. Through studies on vertical structure of precipitation and its latent heat together with radiation of longwave and shortwave, the earth-atmosphere radiation budget affected by cloud and precipitation is going to be understood. Moreover, through studies on relationship among cloud, precipitation and water vapor, the efficiency of cloud and precipitation and its influence on regional water cycle are going to be analyzed. Through numerical simulations and contrast tests by changing physical parameters related to cloud and precipitation, by changing places over the Plateau or Non-Plateau in weather model, the key parameters related to cloud and precipitation processes impacted on simulations of weather model is going to be identified, which will be helpful to improve simulations of weather model. From the perspective of cloud physics and atmospheric thermal dynamics, the results of this proposal will enhance our comprehensive cognition on the physical process of cloud and precipitation, energy budget and water cycle over the Tibet Plateau.

青藏高原云降水物理认识的不足已严重影响了天气模式对高原云物理过程等描述的客观性。本项目将基于前期已取得的成果，特别是探测数据基础，通过集成星载及地基多源探测数据和再分析资料，建立多时空尺度高原云参数、降水、潜热及大气参数的综合数据集；利用该综合数据集，研究高原天气系统演变过程云降水宏微观参数的时空变化，认知高原主要天气系统活动相应的云参数、降水类型及强度等时空变化特征；研究降水云团的垂直结构及潜热垂直结构和长短波辐射，认知云降水对高原地气辐射收支的作用；研究高原云参数、降水强度及水汽等大气参数之间关系，认知云降水效率及其对区域大气水分循环的影响程度；研究高原与非高原天气模式中云降水物理参数的差异，认知影响天气模式中高原云降水物理过程的关键参数，提高天气模式对高原云降水过程的模拟。本研究将从云雾物理学视角及大气热动力学视角，提升对青藏高原云降水物理过程及其对能量收支及水分循环的综合认知。

项目依据任务书计划内容进行了的研究，建立了卫星多仪器观测数据、再分析数据和地面探空数据等的融合方法，并建立了用于青藏高原云降水及辐射的多套融合数据、地基站气象参数与星载测雨雷达降水廓线的融合数据集等。揭示了青藏高原及周边地区昼间云的可见光和红外信号空间分布特征、云参数及云量与辐射通量的关系、云量和云辐射日变化特征。揭示了青藏高原夏季几种典型降水结构及大气温湿结构特点，并率先揭示了夏季青藏高原降水强度、降水频次、最大降水回波强度及其高度等参量的空间分布特点及其日变化空间分布特点、雨团几何参数和物理参数特征及其两者之间关系。揭示了夏季青藏高原降水结构独特的原因，即高海拔地形压缩了青藏高原对流层厚度，进而造成高原不同于非高原的降水结构，指出深厚弱对流降水是夏季青藏高原主要的降水类型，并揭示了深厚强降水、深厚弱降水和浅薄降水的日变化空间分布特点，率先揭示了夏季青藏高原穿透性对流降水的结构特征及相应的大气温湿廓线特点。率先揭示了喜马拉雅山脉南坡的云宏观参数和云微观参数的分布特征和昼夜云体剖面垂直结构差异；率先揭示了南坡降水强度及频次、降水深厚度及降水率随地形海拔高度的变化特征和日变化特征及其机理；率先揭示了喜马拉雅南坡地面风场类型及相应的降水回波结构和降水粒子谱特征。揭示了青藏高原东坡和东南坡降水结构特点、高原东南部大峡谷喇叭口地型的云系结构特征和昼夜差异及大气环流特征。建立了利用降水垂直结构计算降水潜热结构的物理反演方法、降水廓线结合再分析资料ERA5的潜热反演算法，获得了青藏高原潜热时空分布。揭示了夏季青藏高原及周边地区昼间云水的时空分布特征及区域差异、不同相态云顶的云参数差异，并揭示了青藏高原水汽收支的气候态和水汽输送通道特点。通过数值模拟方法研究，揭示了青藏高原复杂地形对水汽输送的影响及其对高原降水强度的影响程度。