MOisture Transport pathways and Isotopologues in water Vapour (MOTIV)

大气水和环流之间通过辐射效应、潜热释放和云反馈机制的耦合是我们目前对气候系统理解的主要限制。对具有不同分辨率和参数化的不同模型或模型设置进行比较可以对潜在问题提供有价值的见解，但对于关键的模型测试，需要观测数据。在这方面，对流层水汽同位素体可作出独特的贡献。它们的比值提供了关于大气水的来源条件以及大气和云中所涉及的转化过程的信息。最近在建立模型和观测这些比率方面取得了很大进展，因此现在可以在全球范围内以高空间和时间分辨率进行综合分析。该项目的目的是建立对流层水汽同位素体，作为测试大气水分路径模型表示的观测工具，从而为应对气候研究中的上述关键挑战作出贡献。为了实现统计鲁棒性，我们将产生前所未有的自由对流层{H2O，deltaD}对（deltaD是HD 16 O和H216 O之间的标准化比率）。这将是第一次提供经过验证的观测数据集，涵盖大面积，长时间段，包括早晨和晚上的测量。与此同时，一个具有同位素表示的高分辨率气象模型将用于分析水分来源和路径及其相关的同位素信号。这种结合观察建模的方法将提供独特的机会，模型评估，并为推进所涉及的过程的理解。同位素体的潜力将在三个不同的气候有趣的地区展示。在欧洲，我们的方法将提供有价值的洞察水分来源和同位素信号之间的关键关系，在高度多变的天气条件。在亚热带北大西洋的同位素将被用于跟踪海洋边界层和自由对流层之间的混合，其在模式中的差异处理被认为是一个很大的云反馈气候模式的不确定性的一个重要原因。在西非的同位素用于评估西非季风的模型表示，特别是相关的水平水分输送，陆地水分循环和昼夜变化相关的垂直混合。特别感兴趣的是有组织的对流在影响季风环流和相关的水通道的作用。这些结果将有助于识别和更好地理解现有天气和气候模型的缺陷，并提供一个新的框架来指导未来的模型改进。

The coupling between atmospheric water and circulation via radiative effects, latent heat release and cloud feedback mechanisms is a main limitation in our current understanding of the climate system. A comparison of different models or model setups with different resolutions and parameterisations can give valuable insight into the underlying problems, but for critical model tests observational data are required. In this context tropospheric water vapour isotopologues can make a unique contribution. Their ratios provide information about the source conditions of atmospheric water and the involved transformation processes in the atmosphere and in clouds. There has recently been large progress in modelling and observing these ratios, such that a combined analysis is now feasible at high spatial and temporal resolution and on a global scale. The aim of this project is to establish tropospheric water vapour isotopologues as an observational tool for testing the model representation of atmospheric moisture pathways, thereby contributing to the aforementioned key challenges in climate research. To achieve statistical robustness, we will generate an unprecedented amount of free tropospheric {H2O, deltaD}-pairs (deltaD is the standardised ratio between HD16O and H216O). For the first time a validated observational dataset will be available that covers large areas, long time periods and include morning and evening measurements. At the same time, a high-resolution meteorological model with isotopologue representation will be used for analyzing moisture sources and pathways and their associated isotopologue signals. This combined observational-modeling approach will provide unique opportunities for model evaluation and for advancing the understanding of the involved processes. The potential of the isotopologues will be demonstrated in three different climatologically interesting regions. In Europe our approach will provide valuable insight into the key relationship between moisture sources and isotopologue signals in highly variable weather conditions. Over the subtropical North Atlantic the isotopologues will be used for tracing mixing between the marine boundary layer and the free troposphere, whose discrepant treatment in models is thought to be one important reason for a large cloud feedback uncertainty in climate models. Over West Africa the isotopologues serve to evaluate the model representation of the West African monsoon, particularly the associated horizontal moisture transport, terrestrial moisture recycling and the diurnal variations related to vertical mixing. Of particular interest will be the role of organised convection in influencing the monsoon circulation and the associated water pathways. Together these results will help to identify and better understand deficits in existing weather and climate models and provide a new framework to guide future model improvement.