近60 a来秦岭山地≥10℃积温时空演变及亚热带-暖温带界线问题

Assessing the Boundary Between Subtropical and Warm Temperate Zones and the Spatiotemporal Evolution of the Active Accumulated Temperature of≥10℃in the Qinling Mountains from 1960 to 2019.

选用秦岭及其周边74个气象站点的逐日气温实测数据,采用M-K检验、Anusplin等研究方法,对1960—2019年秦岭山地≥10℃积温的时空变化以及亚热带-暖温带的界线变化进行分析。结果表明:(1)从时间尺度上看,秦岭山地≥10℃积温呈现增加的趋势,其变化率为71.72℃·(10 a)^(-1)。>1000~2000和>2000~3000℃积温段区域面积占比逐年减少,>3000~4000和>4000℃积温段区域面积占比逐年增加;≤1000℃积温段区域面积占比呈先增加后减少的变化趋势。(2)从空间尺度上看,秦岭山地≥10℃积温在南北方向表现出中间低周边高、东多西少、南多北少,由低海拔向高海拔逐渐减少的规律;研究区积温高值区面积增加,积温低值区面积减少;秦岭山地≥10℃积温增加趋势显著,其中秦岭北坡增加最为明显。(3)对比阶段Ⅰ(1960—1989年)和阶段Ⅱ(1990—2019年),亚热带-暖温带分界线整体向高海拔攀升和向高纬度北移,秦岭以北“跨越式”进入了亚热带气候格局,随着气候变暖,秦岭亚热带北界可能会跨越秦岭山脉。

The changes of the boundary between subtropical and warm temperate zones and the spatiotemporal evolution of the actively accumulated temperature of≥10℃(AAT10)in the Qinling Mountains from 1960 to 2019 was analyzed by using the sliding mean temperature over five days,the Mann-Kendall test,and the Anusplin method based on the daily average temperature data from 74 meteorological stations in and around the Qinling Mountains(QMs).The results show that(1)at the temporal scale,the AAT10 had increased at a rate of 71.72℃·(10 a)^(-1) in the QMs since 1960.The areas of 1000<AAT10≤2000℃and 2000<AAT10≤3000℃decreased from 1960 to 2019,and the areas of AAT10>4000℃and 3000<AAT10≤4000℃increased from 1960 to 2019.The area of≤1000℃increased from 1960 to 1989 and decreased from 1990 to 2019.(2)At the spatial scale,the AAT10≥10℃in the Qinling Mountains showed a trend of“lower in the middle and higher in the periphery”,“more in the east and less in the west”,and“more in the south and less in the north”;additionally,it occupied the largest area and was followed by that of AAT10>4000℃and 2000<AAT10≤3000℃,and it gradually decreased from low altitude to high altitude.The area of the high accumulated temperature increases and the area of the low accumulated temperature decreases.The AAT10 in the QMs increased significantly,among which the north slope of the QMs increased significantly.(3)In contrast to periodⅠ(1960-1989)and periodⅡ(1990-2019),the subtropical-warm temperate boundary climbed significantly to higher altitudes and moved northward,and in periodⅡ,the“leapfrog”in northern Qinling entered the subtropical climate pattern.As the climate warms,the boundary of the subtropical zone may break through the Qinling Mountains.