川渝地区夏季极端气温变化及未来预估

Summer Extreme Temperature Changes and Future Projections in Sichuan-Chongqing Region

摘要:

本文利用CN05.1数据集1961~2012年全国日平均气温资料和CMIP5模式数据集中的三个模式中等排放情境RCP4.5日平均气温资料，计算川渝地区夏季区域平均气温；并使用百分位阈值方法筛选出每一年夏季川渝极端高温事件与极端低温事件的发生频次，分析川渝地区夏季近52年极端气温变化趋势，并对未来直到21世纪末川渝地区夏季极端气温变化趋势做出预估。对观测资料的分析表明，过去52年间，川渝地区夏季极端高温事件整体发生频次呈上升趋势，极端低温事件发生频次整体呈下降趋势，说明川渝地区夏季极端高温呈上升趋势，极端低温呈下降趋势。对RCP4.5情景下三个模式预估资料的研究表明，未来直到21世纪末，川渝地区夏季极端高温事件发生频次呈现持续上升趋势；至2050年，对比现在的极端高温阈值，川渝地区每一年夏季将有超过一半的时间超过此极端高温阈值；极端低温事件发生频次呈现下降趋势，2050年以后，川渝地区大部分年份的夏季可能均将不会发生极端低温事件。表明了在未来增暖的气候背景下，川渝地区极端高温事件将有频发的趋势。

Abstract: Based on the CN05.1 daily observation temperature data from 1961 to 2012 and the daily model temperature data from CMIP5 models in the medium emission scenario RCP4.5, this study evaluated the extreme temperature in summer in Sichuan-Chongqing region between observation and models data. We used the percentile threshold method to define the extreme high temperature events and extreme low temperature events in Sichuan-Chongqing region in summer. The extreme temperature changes of Sichuan-Chongqing region in summer in recent 52 years were analyzed, and the change trend of summer extreme temperature in Sichuan-Chongqing region until the end of the 21st century was predicated. The analysis of the observed data showed that the frequency of extreme high temperature events in Sichuan-Chongqing region in summer had been on the rise as a whole, and the frequency of extreme low temperature events had been on the decline as a whole in the past 52 years, which indicated that the extreme high temperature in Sichuan-Chongqing region in summer was on the rise and the extreme low temperature was on the decline. The study of three models under RCP4.5 scenario showed that the frequency of extreme high temperature events in Sichuan-Chongqing region will continue to increase in the future. By 2050, compared with the current extreme high temperature threshold, more than half of the time in Sichuan-Chongqing region will exceed the extreme high temperature threshold in summer each year; the frequency of extreme low temperature events will decrease, and after 2050, Sichuan-Chongqing region will be affected by the extreme high temperature threshold. Extreme low temperature events may not occur in summer in most years of the region. It shows that under the future warming climate background, the trend of extreme high temperature events in Sichuan-Chongqing region will be much more frequent.