Evaluating heat extremes in the UK Climate Projections (UKCP18)
Evaluating heat extremes in the UK Climate Projections (UKCP18)
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DOI：
10.1088/1748-9326/abc4ad
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发表时间：
2020-10
影响因子：
6.7
通讯作者：
Alan T. Kennedy-Asser;Oliver Andrews;D. Mitchell;R. Warren
中科院分区：
文献类型：
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作者：
Alan T. Kennedy-Asser;Oliver Andrews;D. Mitchell;R. Warren
近年来，英国夏季热浪导致数千人死亡，极端温度和高湿度增加了健康风险。在这里，英国气候预测2018（UKCP 18）与观测（HadUK-Grid）和再分析数据（ERA 5）进行了比较，以量化模型在捕获平均值，极端值（第95至99.5次）以及气候状态和热应力指标（简化湿球全球温度，sWBGT; Humidex;表观温度）的变化方面的性能。UKCP 18进行的模拟一般执行以及或更好地复制观测到的空间格局的英国气候与极端高温，平均RMSE值小于30%的CMIP 5模型。UKCP 18模拟中空间分辨率的增加表明，与观测结果相比，模型性能略有改善（RMSE值平均低1.5%），但分辨率类内的集合成员之间存在相当大的差异。对于UKCP 18和CMIP 5模型，当使用具有较大蒸汽压分量（如sWBGT）的热应力指标时，捕获极端热量特征的模型误差通常会降低。最后，观测到的英国夏季温度的第95百分位数比最近过去（1981-2000年）的夏季平均值有60%以上的年际变化。与HadUK-grid和ERA 5相比，UKCP 18模型（约33%）低估了这种影响。与全球平均温度的预测未来变化相比，英国夏季平均温度和第95百分位温度的增长速度比全球平均温度快。
In recent years, UK summer heatwaves have resulted in thousands of excess deaths, with both extreme temperatures and high humidity increasing health risks. Here, the UK Climate Projections 2018 (UKCP18) are compared to observational (HadUK-Grid) and reanalysis data (ERA5) to quantify model performance at capturing mean, extremes (95th to 99.5th percentiles) and variability in the climate state and heat stress metrics (simplified wet bulb global temperature, sWBGT; Humidex; apparent temperature). Simulations carried out for UKCP18 generally perform as well as or better than CMIP5 models in reproducing observed spatial patterns of UK climate relating to extreme heat, with RMSE values on average ∼30% less than for the CMIP5 models. Increasing spatial resolution in UKCP18 simulations is shown to yield a minor improvement in model performance (RMSE values on average ∼5% less) compared to observations, however there is considerable variability between ensemble members within resolution classes. For both UKCP18 and CMIP5 models, model error in capturing characteristics of extreme heat generally reduces when using heat stress metrics with a larger vapour pressure component, such as sWBGT. Finally, the 95th percentile of observed UK summer temperature is shown to have ∼60% greater interannual variability than the summer mean over the recent past (1981–2000). This effect is underestimated in UKCP18 models (∼33%) compared to HadUK-grid and ERA5. Compared to projected future changes in the global mean temperature, UK summer mean and 95th percentile temperatures are shown in increase at a faster rate than the global mean.