青海省不同等级寒冷日数时空演变特征OA北大核心CSTPCD

Based on the daily minimum temperature measured at 42 meteorological stations in Qinghai Province from 1961 to 2019,the spatial and temporal evolution of different grades of cold days(extreme cold,extremely cold,severe cold,major cold,minor cold,light cold,slightly cold,cool)were analyzed.The results showed that:(1)From 1961 to 2019,the number of cold days in Qinghai Province gradually increased with decreasing levels,mainly dominated by slightly cold days.The total number of cold days showed an overall decreasing trend,with a significant rapid decrease occurring in 1995.The decrease in total cold days was mainly caused by the reduction in extremely cold days.After the climate abrupt change in 1997,the trends of severe cold,major cold,minor cold,light cold,slightly cold,and total cold days decreased,while the trend of extremely cold days increased.The trends of extreme cold and cool days decreased and increased respectively,with a distribution roughly equal.(2)Qinghai Province exhibits significant spatial differences in cold days,with the total number of cold days grad-ually increasing with altitude,and the trends of higher-level cold days are more pronounced.As the level of cold-ness decreases,the trends of increase and decrease develop towards lower latitudes and areas with relatively low-er altitudes.(3)The numbers of extreme cold,extremely cold,severe cold,light cold,slightly cold,and total cold days gradually decrease with increasing annual mean temperature,while the numbers of major cold,minor cold,and cool days gradually increase with increasing annual mean temperature.(4)Except for severe cold days,the numbers of other levels of cold days in Qinghai Province show persistence,and the downward trend will continue in the future,but the strength of persistence varies.