1960—2019年秦岭气候带界限的变化研究

受全球变化的影响,温度带边界在空间上的变化呈现出向高纬度方向显著移动的趋势,其中亚热带区空间分布对全球变暖的响应较为敏感,对其边界空间变化特征的研究对于认识全球变化对自然景观的潜在影响具有重要科学意义。基于秦岭及其周边74个气象站点1960—2019年日均气温数据,选取保证率80%的日均温≥10 ℃持续日220天等值线和1月0 ℃等温线为北亚热带北界指标,探讨了近60年气候变暖背景下秦岭气候带界限的变化趋势。研究表明：（1）1960—2019年秦岭日均温≥10 ℃持续日呈显著上升趋势,其变化率为3.268 d/10 a;秦岭1月平均气温呈弱显著上升趋势,其变化率为0.179 ℃/10 a。（2）60年来秦岭北亚热带北界发生了明显的抬升,平均抬升高度约为228.89 m;从经度上看,中段106°~111°E范围内北亚热带北界的变化最为强烈,60年来上升高度达308.81 m,明显高于东西北三段（东段上升165.69 m,西段上升243.33 m,北段上升267.01 m）。（3）60年来秦岭北亚热带过渡带出现了明显的攀升,且向北移动;秦岭以北“跨越式”地出现北亚热带气候格局。气温突变后,秦岭北亚热带过渡带形成从秦岭南坡延伸到秦岭东部,并向北推进向西进入关中平原的格局,秦岭南坡作为北亚热带和暖温带的分界作用有所减弱。随着气候的变暖,秦岭北亚热带过渡带可能部分或整体转变为北亚热带,北亚热带将从秦岭南坡到秦岭北坡呈连续带状分布,北亚热带北界可能会跨越秦岭山脉。

Changes of climate zone boundary of the Qinling Mountains from 1960 to 2019

Influenced by global change, temperature zone boundaries significantly have moved toward higher latitudes, especially the spatial distribution of subtropical zones is more sensitive to global warming, and the study of the spatial change characteristics of its boundaries is of great significance to understand the potential impact of global changes on natural landscapes. Based on the daily average temperature data from 1960 to 2019 from 74 meteorological stations in and around the Qinling Mountains, the 220-day contour of daily average temperature ≥10 ℃ continuous days with 80% guarantee and the 0 ℃ isotherm in January were selected as the northern boundary indicators of the north subtropics, and the trends of the boundaries of the Qinling climate zone under the background of climate warming in the past 60 years were explored. The results showed that: (1) The number of days with daily average temperature ≥10 ℃ in the study area during the period 1960-2019 showed a significant upward trend, with a change rate of 3.268 d/10 a; the average January temperature showed a weakly significant upward trend, with a change rate of 0.179 ℃/10 a. (2) The northern boundary of the north subtropics in the Qinling Mountains underwent a significant uplift in the past 60 years, with an average height of about 228.89 m. In terms of longitude, the northern boundary of the north subtropics in the middle section from 106°E to 111°E had the greatest change, with a rise of 308.81 m in the 60 years, which is significantly higher than the other two sections in the north and west (165.69 m in the east, 243.33 m in the west, and 267.01 m in the north). (3) The northern subtropical transitional zone of the Qinling Mountains climbed significantly in the 60 years and moved northward. Also, the "north" subtropical zone north of the Qinling Mountains climbed significantly and moved northward; the northern subtropical transitional zone of the Qinling Mountains climbed significantly and moved northward in the past 60 years. After the abrupt change in temperature, the northern subtropical transitional zone extended from the southern slope of the Qinling to the eastern part of the mountains and advanced northward into the Guanzhong Plain, and the role of the southern slope as the boundary between the north subtropical and warm temperate zones was weakened. With the climate warming, the northern subtropical transitional zone may continue to climb to higher elevations, and the northern subtropical transitional zone may be partially or integrally transformed into the north subtropical zone, and the north subtropical zone will be continuously distributed from the southern slope of the Qinling Mountains to the northern slope, and then the northern boundary of the north subtropical zone breaks through the Qinling Mountains.