More extreme-heat occurrences related to humidity in China
Wenyue He, Huopo Chen
Abstract
The co-occurrence of day and night compound heat extremes has attracted much attention because of the amplified socioeconomic and human health impacts. Based on ERA5 hourly reanalysis data, this study characterized and compared extreme day–night compound humid-heat/high-temperature events (CHHEs/CHTEs) in China as well as the associated impacts. Results indicated that the spatial patterns of summer mean extreme CHHEs are consistent with those of extreme CHTEs, except in northwestern China. A greater magnitude of these two types of events dominates over southern China, but the high-frequency centers are mainly observed over northern China. Significant increasing trends in frequency are captured nationwide, but with much stronger trends detected in northern and western China. Further analysis shows that the anomalies of humidity play a more important role than those of temperature in the occurrence of extreme CHHEs in most parts of China, but particularly in eastern regions. Since 1961, the human population and land areas of China have experienced strongly increasing compound heat extremes, with a faster rate of exposure to extreme CHHEs than to extreme CHTEs. Our study highlights the importance of understanding regional changes in humidity when considering heat stress in the future. 极端日夜复合高温往往会造成更为严重的社会经济影响及健康风险, 受到了广泛关注.本文基于ERA5逐小时资料, 针对中国区域极端日夜复合湿热和高温事件的变化及其影响进行了比较分析.结果指出, 中国区域夏季极端湿热和高温在空间分布上较为一致, 强度高值区主要分布在南方地区, 但高频中心主要出现在北方地区.两类事件发生频次在全国范围内均呈明显增加趋势, 尤其在西部和北部地区.进一步研究表明, 在中国大部分地区, 湿度异常在极端湿热事件变化中有着十分重要的作用, 部分区域甚至超过温度异常的影响.随着极端湿热事件的增加其影响也在加剧, 自1961年以来中国暴露于极端湿热事件的人口数量和城市面积增速明显大于高温事件.