The characteristics of summer sub-hourly rainfall over the southern UK in a high-resolution convective permitting model
The characteristics of summer sub-hourly rainfall over the southern UK in a high-resolution convective permitting model
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DOI：
10.1088/1748-9326/11/9/094024
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发表时间：
2016-09-01
影响因子：
6.7
通讯作者：
Blenkinsop, S.
中科院分区：
文献类型：
--
作者：
Chan, S. C.;Kendon, E. J.;Blenkinsop, S.
山洪暴发通常是由每小时的极端降雨量引起的。在这里，我们通过英国气象局最先进的对流允许模型模拟当前和未来的气候来检查英国南部每小时 10 分钟的降雨量。观测研究表明，部分地区夏季降雨持续时间会随着气温的升高而缩短。持续时间的减少与每小时极端降雨量的加剧同时发生。这表明，在气候变化的情况下，降雨持续时间和每小时降雨强度可能会发生变化，这对山洪风险的未来变化具有重要影响。模拟显示每小时降雨量明显增强，但我们没有发现降雨持续时间有任何减少。事实上，模型结果表明相反的情况，未来极端和非极端降雨事件都会略有延长（可能微不足道）。延长是由降雨强度驱动的，但事件轮廓的形状没有明显变化。还检查了其他指标，包括 10 分钟强降雨与温度之间的关系以及回水水平变化；所有这些都与每小时降雨量的结果一致。无法在每小时时间尺度上评估模型性能，这凸显了对高质量每小时观测的需求。这种每小时一次的观测将加深我们对未来山洪风险的了解。
Flash flooding is often caused by sub-hourly rainfall extremes. Here, we examine southern UK sub-hourly 10 min rainfall from Met Office state-of-the-art convective-permitting model simulations for the present and future climate. Observational studies have shown that the duration of rainfall can decrease with temperature in summer in some regions. The duration decrease coincides with an intensification of sub-hourly rainfall extremes. This suggests that rainfall duration and sub-hourly rainfall intensity may change in future under climate change with important implications for future changes in flash flooding risk. The simulations show clear intensification of sub-hourly rainfall, but we fail to detect any decrease in rainfall duration. In fact, model results suggest the opposite with a slight (probably insignificant) lengthening of both extreme and non-extreme rainfall events in the future. The lengthening is driven by rainfall intensification without clear changes in the shape of the event profile. Other metrics are also examined, including the relationship between intense 10 min rainfall and temperature, and return levels changes; all are consistent with results found for hourly rainfall. No evaluation of model performance at the sub-hourly timescale is possible, highlighting the need for high-quality sub-hourly observations. Such sub-hourly observations will advance our understanding of the future risks of flash flooding.