Hydrometeorological compound events cause severe economical, societal and environmental damage, but their investigation is difficult as they occur rarely and are multivariate. Here we use 50 high-resolution climate simulations from the single model initial condition large ensemble CRCM5-LE to examine two such compound event types in southern Norway: (1) Heavy rainfall on saturated soil during the summer months (June, July, August, September; SES) and (2) Concurrent heavy rainfall and snowmelt (rain-on-snow; ROS). We compare present-day conditions (1980–2009) with future conditions under a high-emission scenario (2070–2099) and investigate the impact of climate change on the frequency and spatial distribution of SES and ROS events. We find that the probability of occurrence of SES events during the summer increases by 38% until 2070–2099 over the whole study area. The areas with the highest occurrence probability extend from the west coast into the interior. In contrast, the frequency of ROS is projected to decrease by 48% on average, largely driven by decreases in snowfall. Moreover, the spatial pattern of ROS are projected to change, with the most frequently affected areas shifting from the west coast towards the inner country. Our study highlights the benefits of single model large ensemble simulations for the analysis of compound events.

水文气象复合事件会造成严重的经济，社会和环境破坏，但由于它们很少发生并且是多变量的，因此很难进行调查。在这里，我们使用来自单个模型初始条件大型整体CRCM5-LE的50个高分辨率气候模拟来研究挪威南部的两种此类复合事件类型：（1）夏季（6月，7月，8月， 9月； SES）和（2）同时出现强降雨和融雪（雪上雨； ROS）。我们将高排放情景（2070-2099）中的当前状况（1980-2009）与未来状况进行了比较，并研究了气候变化对SES和ROS事件发生频率和空间分布的影响。我们发现，在整个研究区域内，直到2070-2099年夏季发生SES事件的可能性都增加了38％。发生概率最高的区域从西海岸延伸到内部。相比之下，ROS的频率预计平均降低48％，这在很大程度上是由降雪引起的。此外，ROS的空间格局预计将发生变化，受影响最频繁的地区将从西海岸向内陆转移。我们的研究强调了单一模型大型集成仿真对复合事件分析的好处。此外，ROS的空间格局预计将发生变化，受影响最频繁的地区将从西海岸向内陆转移。我们的研究强调了单一模型大型集成仿真对复合事件分析的好处。此外，ROS的空间格局预计将发生变化，受影响最频繁的地区将从西海岸向内陆转移。我们的研究强调了单一模型大型集成仿真对复合事件分析的好处。