Extreme high temperature (EHT) events have caused serious impact on society. In previous research, EHT indices seldom consider spatial aggregation. To conduct the comprehensive evaluation, the global EHT days from 1979 to 2017 have been evaluated in terms of high temperature duration, accumulative temperature intensities and magnitude of spatial aggregation based on ERA‐Interim 2 m air temperature data set. In addition, abnormal warming of polar and ocean surfaces has rarely been addressed in global‐scale studies. To address this deficiency, the indices of EHT days are normalized by maximum in history for each location. To solve the time discontinuity problem on EHT spatiotemporal distribution in previous studies, we utilized spatiotemporal scan statistics to detect EHT spatiotemporal clusters (EHT‐STCs), and clusters correspond to a certain spatiotemporal extent where the EHT events are aggregated. This method actualizes time‐continuous and spatiotemporal integral detection. The results show the following: 1. There are apparent changes in EHT‐STC spatial distribution after 1999, so 1999 can be recognized as the critical time node of EHT‐STC spatial transformation. 2. After 1999, the EHT‐STC number gradually increased, and the duration and spatial coverage of EHT‐STC gradually expanded. Overall, EHT‐STCs display a significant northward migration, with an average northward movement of 7.03° for each transition from 1979 to 2017. 3. There are differences in the extremity and transformation process in different regions. EHT‐STCs in Antarctica are concentrated before 1992, with the strongest EHT extremity; EHT‐STCs in the Arctic and middle‐low latitude continents are concentrated after 2010 and 1999 respectively, both with a strong EHT extremity. There is a similar EHT‐STC number in the middle‐low latitude ocean before and after 1999 with the weakest extremity. These results contribute to determining EHT causes and future trends in global climate change.

中文翻译：

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全球极端高温星团的空间转换过程和关键时间节点检测

极端高温（EHT）事件已对社会造成严重影响。在以前的研究中，EHT指数很少考虑空间聚集。为了进行综合评估，根据ERA-Interim 2 m气温数据集，对1979年至2017年的全球EHT天进行了高温持续时间，累积温度强度和空间聚集量的评估。此外，全球范围的研究很少解决极地和海洋表面异常变暖的问题。为了解决此不足，EHT天数的索引通过每个位置的历史最大值进行了归一化。为了解决先前研究中EHT时空分布的时间不连续性问题，我们利用时空扫描统计数据来检测EHT时空簇（EHT-STC），聚类对应于EHT事件聚集的某个时空范围。该方法实现了时间连续和时空积分检测。结果表明：1. 1999年以后EHT-STC空间分布发生了明显变化，因此1999年可被视为EHT-STC空间变换的关键时间节点。2. 1999年以后，EHT-STC的数量逐渐增加，EHT-STC的持续时间和空间覆盖范围逐渐扩大。总体而言，EHT-STC表现出显着的北移，从1979年到2017年，每个过渡的平均北移为7.03°。3.不同地区的末端和转换过程存在差异。南极洲的EHT-STC集中在1992年之前，其EHT末端最强。北极和中低纬度大陆上的EHT-STC分别集中在2010年和1999年以后，都具有很强的EHT末端。在1999年前后，中低纬度海域的EHT-STC值相似，而四肢最弱。这些结果有助于确定EHT的原因以及全球气候变化的未来趋势。