秦岭太白山气温直减率时空差异性研究

在评估山地生态系统对气候变化响应的过程中,作为气温要素的重要输入参数,气温直减率（γ）的精确性直接影响到相关科研工作的真实性和可靠性。本文基于秦岭主峰太白山（3771.2 m）11个分布于南北坡和不同海拔的标准气象站点2013-2015年连续3年实测日均温资料和25 m×25 m空间分辨率的DEM数据,研究了太白山气温直减率在不同时间尺度上的变化规律及不同坡向上的空间分布特征。结果表明：① 2013-2015年太白山年均γ北坡均大于南坡,北坡为0.513 ℃/100m,南坡为0.499 ℃/100m;北坡年均γ随海拔变化表现出一定的差异性,而南坡相对稳定。② 年内γ在不同时间尺度上均存在明显差异,且南北坡变化趋势不一致。在季尺度上,γ最大值北坡为夏季,为0.619 ℃/100m,而南坡最大出现在春季,为0.546 ℃/100m,最小值均为冬季,南北坡分别为0.449 ℃/100m和0.390 ℃/100m;春季和夏季,北坡γ均大于南坡,而冬季相反,北坡小于南坡,秋季几乎无差异。在月尺度上,气温相对高的月份γ亦较高,北坡γ变化幅度大于南坡;年始和年末（11-12月、1-2月）北坡γ小于南坡,而5-9月北坡大于南坡,且南北坡γ相差较大。③ 经数据可信度分析,所获得的γ可较为客观地反映太白山气温随海拔变化的规律性,将为山地气温空间分布规律及其生态系统响应等定量研究提供理论基础。

Temporal and spatial variability of air temperature lapse rates in Mt. Taibai,Central Qinling Mountains

Air temperature lapse rate (γ) is taken as one of key input parameters when we evaluate the response of the mountain ecosystem to climate change, and its accuracy is very useful to the related research in the future. In this paper, based on the datasets built based on data from standard meteorological stations in Mt. Taibai, the tempo-spatial distribution characteristics for the variations of γ were evaluated by using DEM images at a 25-m resolution as well as daily average temperature during the period of 2013-2015. The average value of annual γ on the northern slope (0.513℃/100 m) was larger than that on the southern slope (0.499℃/100 m) during the three years, and a greater variation in different altitude regions was found on the northern slope than on the southern slope. The variability of γ was significant at different time-scales. At the seasonal scale, the peak of γ (0.619℃/100 m) on the northern slope occurred in summer, while the peak of γ (0.546℃/100 m) on the southern slope appeared in spring. Meanwhile, the minimums of γ on both slopes (0.390℃/100 m on the northern slope and 0.449℃/100 m on the southern slope) were found in winter. Compared with the southern slope, the values of γ on the northern slope were higher in spring and summer, while they were lower in winter and almost the same in autumn. At the monthly scale, the larger values of γ appeared in the warmer months on both slopes, and the larger variation in γ was found on the northern slope. The values of γ were higher on the southern slope than those on the northern slope in January, February, November and December, while they were lower from May to September. The results clarified the rule of temperature-altitude variations in Mt. Taibai in recent 50 years, which could provide a theoretical basis for the quantitative researches on temperature distribution characteristics and the response of the ecosystem to climate change in the mountain areas.