Abstract Regional Climate Models (RCMs) generate past and future climate simulations that serve as input for subsequent modelling of impact projections. The most recent coordinated regional climate modelling initiative, CORDEX, provides RCM data for Europe with increased spatial resolution (12.5 km for the CORDEX EUR-11 ensemble) and based on the new Representative Concentration Pathways (RCPs). RCM data from the previous initiative ENSEMBLES had a spatial resolution of 25 km and was based on the SRES emission scenarios. In this contribution we explore the development from ENSEMBLES to CORDEX in a hydrological impact study for the Upper Danube, focussing on the representation of past climate and projections of the future for climate and resulting river discharge. We replicated a hydrological modelling framework, including RCM downscaling and bias correction, that used data of 21 ENSEMBLES RCMs under SRES A1B emission scenario ( Kling et al., 2012 ), and now applied CORDEX EUR-11 data of 32 RCM simulations under RCP4.5 and RCP8.5 emission scenarios. Results with CORDEX show a small improvement in the representation of historical precipitation, but a decline in the accuracy of historical temperature simulations, despite the increase in spatial model resolution. The tendency of ENSEMBLES climate projections is reproduced with the CORDEX RCMs, albeit with slightly higher precipitation in the CORDEX data, yielding a less pronounced reduction in future mean annual discharge for the Upper Danube at Vienna. The previously identified change in discharge seasonality – increasing winter discharge and decreasing summer discharge – is confirmed with the new CORDEX data. Updating climate impact simulations in the presented rigorous replication framework allows analysing specific new information in the latest generation climate model data as well as crystallizing essential expectable patterns of change that need to be addressed in adaptation strategies.

中文翻译：

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从 ENSEMBLES 到 CORDEX：多瑙河上游流量不断变化的气候变化预测

摘要 区域气候模式 (RCM) 生成过去和未来的气候模拟，作为后续影响预测建模的输入。最新的协调区域气候建模倡议 CORDEX 为欧洲提供了空间分辨率更高的 RCM 数据（CORDEX EUR-11 集合为 12.5 公里）并基于新的代表性浓度路径 (RCP)。来自先前倡议 ENSEMBLES 的 RCM 数据具有 25 公里的空间分辨率，并且基于 SRES 排放情景。在这篇文章中，我们探讨了多瑙河上游水文影响研究中从 ENSEMBLES 到 CORDEX 的发展，重点是过去气候的表示以及对气候和由此产生的河流流量的未来预测。我们复制了一个水文建模框架，包括 RCM 降尺度和偏差校正，使用 SRES A1B 排放情景下 21 个 ENSEMBLES RCM 的数据（Kling 等人，2012 年），现在在 RCP4.5 和 RCP8.5 排放情景下应用 32 个 RCM 模拟的 CORDEX EUR-11 数据. CORDEX 的结果显示，尽管空间模型分辨率提高了，但历史降水的表征略有改善，但历史温度模拟的准确性却有所下降。ENSEMBLES 气候预测的趋势用 CORDEX RCM 再现，尽管 CORDEX 数据中的降水量略高，导致维也纳上多瑙河未来年平均流量的减少不太明显。新的 CORDEX 数据证实了先前确定的排放季节性变化——冬季排放增加和夏季排放减少。在提出的严格复制框架中更新气候影响模拟，可以分析最新一代气候模型数据中的特定新信息，并明确需要在适应战略中解决的基本可预期变化模式。