近60年中国省级行政单元极端气候指数的时空变化特征OA

Studying extreme climate change is of paramount significance for safeguarding China′s national security and promoting sustainable socioeconomic development.This research is based on observational data of daily precipitation,mean temperature,maximum temperature,and minimum temperature from 839 meteorological stations across China during the period 1960-2019.By utilizing the 26 extreme climate indices recommended by the World Meteorological Organization,the Sen-Slope estimation method and the Mann-Kendall trend test method were employed to analyze the spatiotemporal characteristics of extreme temperature and precipitation in China.The results indicate that among the extreme temperature indicators,the high values of the extreme cold index are primarily concentrated in the Northeast region.Specifically,the maximum values for frost days and freezing days are 0～225.16 d and 0～107.81 d,respectively.The cold nights and cold days are mainly concentrated at 35 d,with a cold day duration ranging from 9.60 to 19.12 d.The extreme warmth index and the length of the growing season exhibit higher values in the south and lower values in the north.The extreme value index shows a decreasing distribution from north to south.Specifically,the number of summer days and hot nights ranges from 11.82 to 299.07 days and from 0 to 263.22 days,respectively.The number of warm nights and warm days is mainly concentrated between 33 and 35 days.Warm days range from 9.60 to 19.12 days,and the length of the growing season remains between 145.90 and 365 days.The daily temperature range is the largest in the northwest region,followed by the northeast region,and it is smaller in the southern region,ranging from 6.64 to 15.37℃.The extreme minimum daily temperature,extreme maximum daily temperature,extreme minimum daily high temperature,and extreme maximum daily low temperature fluctuate from-11.29 to 18.18℃,4.64 to 25.90℃,1.54 to 23.50℃,and-4.64 to 25.90℃,respectively.In the extreme precipitation index,the distribution of continuous dry days mainly exhibits higher values in the northwest and lower values in the southeast,ranging from 19.28 to 85.60 days.Conversely,the distribution of extremely heavy precipitation days,extremely strong precipitation amounts,maximum precipitation amounts,and precipitation intensity mainly shows lower values in the northwest and higher values in the southeast,with ranges of 2.92～50.00 days,0.71～26.89 days,7.06～84.54 mm,and 2.71～12.59 mm,respectively.Overall,both extreme temperature and extreme precipitation in China are showing an upward trend,but there are significant differences in their spatiotemporal evolution.Among the extreme temperature indicators,the extreme cold index shows a more pronounced downward trend in the central and eastern regions,while the extreme warm index rises rapidly in the central and northern regions,with the extreme value index showing a more prominent increase in the eastern region.Among the extreme precipitation indicators,the number of continuous dry days mainly increases rapidly in coastal areas,while the increase rate of other indicators in the central and eastern regions is higher than that in the western regions.Nationwide,both the extreme temperature index and the extreme precipitation index are expected to increase in the future.