Temporal and spatial variation of extreme temperature in Yimeng Mountain area from 1977 to 2020
[Objective]The dynamic evolution characteristics of extreme temperature events and complex extreme high tempera-ture 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 da-ta,utilizing linear fitting,Mann-Kendall mutation test,and Morlet complex wavelet analysis.The discussion focuses on the re-sponse characteristics of the extreme temperature index to global warming stagnation and the circulation characteristics of persis-tent 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 promo-ted 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 in-dex.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 Moun-tain area was identified as the southern pressure and high-pressure anomaly moving from north to east,and the mid-level subtropi-cal high-pressure anomaly extending west.[Conclusion]In conclusion,Yimeng Mountain area is anticipated to continue the war-ming 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 to-wards the impact of long-term and high-intensity temperature increases in these areas on urban planning,human health,and agri-cultural 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.
extreme temperaturespatial and temporal changethe compound hot extremes at daytime and nighttimeglobal war-ming stagnationYimeng Mountainclimate changehuman activitiesspatiotemporal distribution
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