1981-2022年藏东南4种界限温度时空变化

Spatiotemporal Variation of Four Critical Temperature in Southeastern Tibet from 1981 to 2022

基于1981—2022年藏东南(林芝市)4个气象站点的日平均气温数据,采用线性倾向估计、Person系数、Mann-Kendall检验、优势主导分析等方法,分析了藏东南≥0℃、≥5℃、≥10℃和≥15℃共4种界限温度的时空变化特征。结果表明:(1)受海拔影响,藏东南4种积温总体呈自东南向西北递减的变化特征,各地≥0℃、≥5℃、≥10℃和≥15℃积温分别介于3161.4~4429.9℃·d、2869.2~4018.0℃·d、2273.3~3258.0℃·d和608.8~2133.2℃·d。(2)近42 a藏东南4种界限温度均呈初日提前、终日推迟、持续日数延长的趋势,≥10℃界限温度变幅最小,除初日外,≥15℃界限温度变幅最大。≥0℃和≥5℃持续日数的延长主要是初日提前引起的,≥10℃与≥15℃持续日数的增加主要是终日推迟导致的。4种积温均表现出极显著的增加趋势,增幅分别为123.81℃·d/10 a、136.71℃·d/10 a、76.22℃·d/10 a、166.43℃·d/10 a。(3)年代际变化上,4种积温具有明显的逐年代际增加态势。21世纪10年代是研究时段内最温暖的10 a,这一时期的4种积温比20世纪80年代增加了174.9~437.2℃·d,其中≥15℃积温增幅最大。除≥10℃外,20世纪80—90年代初日推迟、终日提早、持续日数缩短,而21世纪前20 a则截然相反。(4)M-K检验显示,≥10℃初日、终日未发生气候突变,其他界限温度指标发生突变时间多在2004年前后。

Based on the daily average temperature data of four meteorological stations in southeastern Tibet from 1981 to 2022,the spatiotemporal variation characteristics of the four critical temperatures(≥0℃,5℃,10℃and 15℃)were analyzed with the methods of linear trend estimation,Person coefficient,Mann-Kendall test and dominance analysis.The results showed that:(1)Affected by altitude,the four active accumulated temperatures(AAT)generally decreased in southeastern Tibet from southeast to northwest.The AAT(≥0℃,5℃,10℃and 15℃)ranged of 3161.4~4429.9℃·d,2869.2~4018.0℃·d,2273.3~3258.0℃·d and 608.8~2133.2℃·d,respectively.(2)In recent 42 years,the four critical temperatures in southeastern Tibet showed the trend of advancing the initial dates,delaying the final dates and prolongging the number of duration days.The smallest change range was observed with≥10℃critical temperatures,except for the initial date,the change range of≥15℃critical temperature was the largest.The lengthened duration days with≥0℃and≥5℃were mainly caused by the advanced initial date,while the increased duration days with≥10℃and≥15℃were mainly caused by the delayed final dates.As well as,the four AAT showed an extremely significant increase trend,with an increase rate of 123.81℃·d/10a,136.71℃·d/10a,76.22℃·d/10a,and 166.43℃·d/10a,respectively.(3)In terms of inter-decadal changes,the four AAT had obvious increasing of inter-decadal changes.The 2010s was the warmest decade in the study period,that of the four AAT increased by 174.9~437.2℃·d compared with the 1980s,with the largest increase in≥15℃AAT.Except for≥10℃,the initial dates postponed,final dates advanced,and the duration days shortened during the period from 1980s to 1990s,while the first 20 years of the 21st century were the opposite.(4)The M-K test showed that there was no climate mutation on the initial date and final date of≥10℃,and the mutation time of other critical temperature indicators was mostly around 2004.