prime-HYD - High Mountain Asian HYDrological variability

降水是将复杂的大气过程与水文循环、积雪以及冰川和冰盖的质量平衡联系在一起的最重要的气候因素之一。降水也是水资源管理和防灾减灾的一个关键变量，例如洪水和干旱。这一点尤其适用于拟议项目束Prime的研究区域，该区域包括亚洲高山(HMA)，即青藏高原(TP)及其周围的高山山脉。Prime内的研究旨在依靠新的遥感(RS)信息和HMA的高级有限区域大气模拟(HAR*(I))生成和验证改进的网格化降水数据集。该成套项目随后调查了空间和时间模式、特定区域的大尺度驱动因素和控制降水变异性的中到局部尺度过程(2)。关于降水类型和变化性的准确度提高和知识的增强，加强了对区域水文循环的时空变化的了解，包括冰块平衡、季节性积雪波动和亚洲高地不同次区域的地表水储存(3)。PRIME-HYD分项目特别侧重于地表水循环及其如何受到降水和温度变化的影响。为此，选择了HMA的两个试验台盆地：内陆型盘贡湖盆地(1)AT和上雅鲁藏布江盆地(2)，两者都起源于TP附近。建立了两个流域的分布式水文模型，其中包括冰雪模拟组件。该模式是由降维的概率降水产品驱动的，该产品是通过对遥感降水和有限区域大气模式输出的联合贝叶斯处理而获得的，条件是地面观测。来自HAR*模拟的RS温度和2M气温将被类似地处理，这是模拟冰层和积雪所必需的。一旦水文模型根据选定时间窗口的积雪覆盖范围和流量进行了校准和验证，就可以用它来研究通过地表水循环传播的亚十年尺度大气强迫变率及其对河流流量和湖泊水位动态的影响。水文信号将在频域中进行分析，以检测潜在的变化模式。重要的是，这项研究还提供了第一批地面验证的水文模型之一，用于迄今在TP上科学地勘探不足的流域。地面观测将通过中国水利部与该项目的联合进行。

Precipitation is one of the most important climate elements linking complex atmospheric processes with the hydrological cycle, snow cover and mass balances of glaciers and ice caps. Precipitation is also a key variable for water resource management and natural disaster prevention and mitigation such as floods and droughts. This holds particularly true for the study region of the proposed project bundle PRIME, which encompasses High Mountain Asia (HMA), i.e., the Tibetan Plateau (TP) and its surrounding high-mountain ranges. Research within PRIME aims at generating and validating improved gridded precipitation data sets relying on new remote sensing (RS) information and advanced limited-area atmospheric modeling for the HMA, known as HAR* (i). The project bundle subsequently investigates spatial and temporal patterns, region-specific large-scale drivers and meso- to local-scale processes controlling precipitation variability (ii). The improved accuracy and enhanced knowledge on precipitation type and variability enhances the understanding of spatial and temporal variations of the regional hydrological cycle, including ice mass balances, seasonal snow cover fluctuations and surface water storage in different sub-regions of High Asia (iii). The sub-project PRIME-HYD in particular focusses on the surface water cycle and how it is affected by precipitation and temperature variability. To this end two test bed basins in HMA are selected: the endorheic Pangong lake basin (1) at and the Upper Brahmaputra basin (2), both originating in close proximity on the TP. A distributed hydrological model is set up for both basins which includes an ice and snow simulation component. The model is driven by a downscaled probabilistic precipitation product that is obtained through combined Bayesian processing of RS precipitation and limited area atmospheric model output, conditioned on ground observations. RS temperature and 2m air temperature from HAR* simulations, which is necessary for ice and snowpack simulations, will be processed analogously. Once the hydrologic model has been calibrated and validated in terms of snow cover extension and flow rates over a selected time window, it is used to study the propagation of sub-decadal scale atmospheric forcing variability through the surface water cycle and its effects on river flow rates and lake level dynamics on the TP. The hydrologic signals will be analyzed in the frequency domain to detect potential variability patterns. Importantly, the study also delivers one of the first ground-validated hydrological models for to date scientifically underexplored drainage basins on the TP. The ground observations will be obtained through association of the Chinese Ministry of Water Resources with the project.