1951—2017年丽江极端气温和降水事件的变化特征

为系统弄清丽江极端气温和降水事件的变化特征，基于丽江气象站1951—2017年逐日最高气温、最低气温和降水量资料，采用线性倾向估计、Mann-Kendall突变检验、滑动t检验和Morlet复小波的方法对16个极端气温指数和11个极端降水指数的变化趋势、突变和周期特征进行了分析.1)变化趋势分析表明：月最低气温极大值、月最低气温极小值、夏季日数、暖夜日数、暖昼日数、热日持续指数呈显著增加趋势，霜冻日数、冷夜日数、冷日持续指数、月平均日较差呈明显减少趋势，月最高气温极大值、热夜日数、作物生长期呈不显著增加趋势，月最高气温极小值、冷昼日数呈不显著减少趋势，冰封日数在研究期内均为0 d;极端降水指数日降水≥1 mm的降水日数呈显著减少趋势，特强降水量呈显著增加趋势，中雨日数、持续湿期、年总降水量、5日最大降水量均呈不显著减少趋势，大雨日数、强降水量、持续干期、1日最大降水量、降水强度均呈不显著增加趋势.2)突变检验分析表明：部分极端气温指数和降水指数的突变年份显著，大部分指数的显著突变年份集中在20世纪80年代至21世纪初，其余指数的显著突变年份在20世纪50至70年代，并且极端冷事件指数霜...

Variation characteristics of extreme temperature and precipitation events of Lijiang from 1951 to 2017

The main objective of this study is to reveal the variation characteristics of extreme temperature and precipitation events in Lijiang of Yunnan province.The data of daily maximum and minimum temperature and daily precipitation from 1951 to 2017 were obtained from Lijiang Meteorological Station.The variation trends,mutation and period characteristics of 16 extreme temperature indices and 11 extreme precipitation indices have been analyzed with methods of linear regression analysis,Mann-Kendall abrupt change test,moving t test,and Morlet complex wavelet analysis.The results of variation trends are as follows.As for extreme temperature indices,significant increasing trends were observed in TNx,TNn,SU,TN90p,TX90p and WSDI;obvious decreasing trends were observed in FD,TN10p,CSDI and DTR;non-significant increasing trends were observed in TXx,TR and GSL;non-obvious decreasing trends were observed in TXn and TX10p;and the values of ID remained 0 days during the study period.As for extreme precipitation indices,a significant decreasing trend was observed in R1;a significant increasing trend was observed in R99pTOT;non-significant decreasing trends were observed in R10,CWD,PRCPTOT and Rx5day;whereas non-significant increasing trends were observed in R20,R95pTOT,CDD,Rx1day and SDII.The results of mutation test are as follows.Significant mutation years were observed in some extreme temperature and precipitation indices,which usually fall on period from the 1980s to the beginning of the 21st century or period from the 1950s to the 1970s.Furthermore,the extreme cold events indices of FD,TN10p and TX10p showed decreasing trends after the significant mutation years,while the extreme warm events indices of SU,TN90p and TX90p showed increasing trends after the significant mutation years.The values of TR were 1 day in 2015 and 0 days in the remaining years of the study period.The periodic results of wavelet analysis are as follows.The 15 extreme temperature indices (except ID) presented 2-6 quasi-periods ranging at 3-56 years,with 1-3 main periods ranging at 10-56 years.The 11 extreme precipitation indices presented 4-6 quasi-periods ranging from 4-56 years,with 1-3 main periods ranging from 12-56 years.Therefore,there are same or similar main periods for some extreme temperature and precipitation indices.