1977—2020年沂蒙山区极端气温时空变化特征分析

Temporal and spatial variation of extreme temperature in Yimeng Mountain area from 1977 to 2020

【目的】为深入掌握全球变暖背景下沂蒙山区极端气温事件及复合极端高温事件的动态演变特征,以期为预防区域性灾害提供理论参考。【方法】根据1977—2020年沂蒙山区的逐日气温资料,利用线性拟合、Mann-Kendall突变检验法、Morlet复小波分析等方法,对沂蒙山区极端气温事件及昼夜复合高温的时空变化特征进行了分析,并探讨了极端气温指数对全球变暖停滞现象的响应特征及发生持续性昼夜复合高温事件时的环流特征。【结果】结果表明:(1)近44年,沂蒙山区暖指数(TN90、TX90、SU25)呈上升趋势,冷指数(TN10、TX10、FD0)呈现下降趋势,具有昼夜不对称性,昼夜温差缩小,促使昼夜复合高温事件的发生。(2)极端气温指数突变时间大多出现在20世纪90年代和二十一世纪初期,突变时间上冷指数早于暖指数,突变后极端气温暖事件的发生频率增加,极端气温冷事件的发生频率减少;昼夜复合高温事件以2012为界,前期波动不明显,高发于2012—2020年;各极端气温指数及昼夜高温事件均在1998—2012年间响应了全球变暖停滞现象。(3)沂蒙山区西部地区为暖夜日数(TN90)、暖昼日数(TX90)以及昼夜复合高温事件的增速显著高值区。(4)沂蒙山区夏季昼夜复合高温事件在2012—2020年持续性较强,南压高压异常偏北偏东,中层副热带高压异常西伸是影响沂蒙山区持续昼夜复合高温的环流机制。【结论】综上,研究区将延续暖化趋势,沂蒙山西部为极端气温事件及复合极端高温事件的高发区域且在近些年增温显著,应重点关注以上地区长历时高强度增温在城市规划、人类健康和农业生产等方面产生的影响,及时制定适应气候变化的策略和措施,促进沂蒙山区生态环境和社会经济的可持续发展。

[Objective]The dynamic evolution characteristics of extreme temperature events and complex extreme high temperature events under the background of global warming in Yimeng Mountain area are being studied,aiming to provide a theoretical reference for regional disaster prevention.[Methods]The temporal and spatial variations of extreme air temperature events and diurnal combined high temperature in Yimeng Mountain area from 1977 to 2020 were analyzed based on daily air temperature data,utilizing linear fitting,Mann-Kendall mutation test,and Morlet complex wavelet analysis.The discussion focuses on the response characteristics of the extreme temperature index to global warming stagnation and the circulation characteristics of persistent diurnal complex high-temperature events.[Results]The result showed that:(1)Over the recent 44 years,an increasing trend was observed in the warm index(TN90、TX90、SU25)in Yimeng Mountain area,while a decreasing trend was noted in the cold index(TN10、TX10、FD0),with diurnal asymmetry and a narrowing diurnal temperature difference,which has promoted the occurrence of diurnal complex high-temperature events.(2)The abrupt change times of the extreme temperature index mainly occurred in the 1990 s and early 21st century,with the cold index experiencing an earlier abrupt change than the warm index.After the abrupt change,an increase in the frequency of extreme air warm events and a decrease in the frequency of extreme air cold events were observed.The period bounded by 2012 saw diurnal complex high-temperature events,with fluctuations being less obvious in the early stage and the highest occurrence from 2012 to 2020.The global warming stagnation during 1998 to 2012 saw a response from all extreme temperature indices and diurnal high-temperature events.(3)High growth rates in warm days(TN90),warm nights(TX90),and diurnal complex high-temperature events were significantly observed in the western Yimeng Mountain area.(4)A strong persistence of the summer diurnal complex high-temperature event from 2012 to 2020 in Yimeng Mountain area was noted.The circulation mechanism affecting the continuous diurnal complex high temperature in Yimeng Mountain area was identified as the southern pressure and high-pressure anomaly moving from north to east,and the mid-level subtropical high-pressure anomaly extending west.[Conclusion]In conclusion,Yimeng Mountain area is anticipated to continue the warming trend,with the western Yimeng Mountain being a high-incidence area for extreme temperature events and compound extreme high-temperature events,where a significant temperature increase has been noted in recent years.Attention should be directed towards the impact of long-term and high-intensity temperature increases in these areas on urban planning,human health,and agricultural production,with the timely development of strategies and measures to adapt to climate change being crucial.This is aimed at promoting the sustainable development of the ecological environment and social economy in Yimeng mountain area.