LAUSR

Future changes in the 50-yr return level for temperature and precipitation extremes over mainland China are investigated based on a CMIP5 multi-model ensemble for RCP2.6, RCP4.5 and RCP8.5 scenarios. The following indices are analyzed: TXx and TNn (the annual maximum and minimum of daily maximum and minimum surface temperature), RX5day (the annual maximum consecutive 5-day precipitation) and CDD (maximum annual number of consecutive dry days). After first validating the model performance, future changes in the 50-yr return values and return periods for these indices are investigated along with the inter-model spread. Multi-model median changes show an increase in the 50-yr return values of TXx and a decrease for TNn, more specifically, by the end of the 21st century under RCP8.5, the present day 50-yr return period of warm events is reduced to 1.2 yr, while extreme cold events over the country are projected to essentially disappear. A general increase in RX5day 50-yr return values is found in the future. By the end of the 21st century under RCP8.5, events of the present RX5day 50-yr return period are projected to reduce to < 10 yr over most of China. Changes in CDD-50 show a dipole pattern over China, with a decrease in the values and longer return periods in the north, and vice versa in the south. Our study also highlights the need for further improvements in the representation of extreme events in climate models to assess the future risks and engineering design related to large-scale infrastructure in China.摘 要利用CMIP5多个全球气候模式的模拟结果预估了RCP2.6, RCP4.5和RCP8.5温室气体排放情景下不同时期中国地区50年一遇极端温度和降水变化, 包括极端高温(TXx), 极端低温(TNn)最大5日降水量(RX5day)和连续干旱日数(CDD). 首先评估了全球气候模式对中国地区极端温度与降水模拟能力, 在此基础上预估了其变化趋势. 结果表明: 50年一遇TXx的值将增加, TNn的值将减小, 尤其在RCP8.5温室气体高排放情景下, 目前50年一遇的极端高温事件在21世纪末将变为1-2年一遇, 极端冷事件将逐渐消失. 50年一遇的极端降水(RX5day)的量值在未来会增加, 同时目前50年一遇的极端降水事件在21世纪末将变为10年一遇. 极端干旱事件(连续无降雨日数)在中国的北方地区将减少, 而在南方将增加.