prime-HYD - High Mountain Asian HYDrological variability

降水是将复杂的大气过程与水文循环、积雪和冰川和冰盖的物质平衡联系起来的最重要的气候要素之一。降水也是水资源管理以及预防和减轻洪水和干旱等自然灾害的一个关键变量。拟建项目包PRIME的研究区域尤其如此，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内部的研究旨在生成和验证改进的网格降水数据集，这些数据集依赖于新的遥感（RS）信息和HMA的先进有限区域大气模型，即HAR* (i)。项目包随后研究时空格局、特定区域的大尺度驱动因素以及控制降水变率的中尺度到局地尺度过程（ii）。准确性的提高和对降水类型和变率的进一步了解，加强了对区域水文循环的时空变化的了解，包括高亚洲不同次区域的冰质量平衡、季节性积雪波动和地表水储存（三）。子项目PRIME-HYD特别关注地表水循环及其如何受到降水和温度变化的影响。为此，选择了两个HMA的试验台盆地：位于青藏高原附近的内陆班公湖盆地(1)和上雅鲁藏布江盆地(2)。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。该模式由RS降水和有限区域大气模式输出的贝叶斯联合处理得到的缩小比例的概率降水产品驱动，该产品以地面观测为条件。RS温度和2m空气温度从HAR*模拟，这是必要的冰雪模拟，将被类似地处理。一旦水文模式在选定的时间窗口内根据积雪覆盖范围和流量进行了校准和验证，就可以使用它来研究次年代际尺度大气强迫变率通过地表水循环的传播及其对TP的河流流量和湖泊水位动态的影响。水文信号将在频域进行分析，以检测潜在的变化模式。重要的是，该研究还为迄今为止在TP上尚未科学开发的流域提供了第一批经过地面验证的水文模型之一。地面观测数据将通过中国水利部与该项目的合作获得。

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.