青藏高原气温空间分布规律及其生态意义

作为世界第三极的青藏高原,其巨大的块体产生了显著的夏季增温作用,对亚洲乃至全球气候都具有重大影响。但由于高原自然条件严酷,山区气象观测台站很少,气象资料极度匮乏;如果依靠台站数据进行空间插值获得高原气温的空间分布数据,会由于插值点过少而产生较大误差并可能掩盖一些空间信息,因而难以全面反映高原气温的空间分布规律。利用基于MODIS地表温度数据估算的青藏高原气温数据,详细分析各月气温及重要等温线的空间分布格局,并结合林线和雪线数据,初步探讨了高原气温空间分布格局对高原地理生态格局的重要影响。研究表明：① 等温线的海拔高度自高原东北部、东部边缘向内部逐渐升高,等温线在高原内部比东部边缘高500~2000 m,表明相同海拔高度上气温自边缘向高原内部逐渐升高。② 高原西北部的羌塘高原、可可西里为高原的寒冷区,全年有7个月的气温低于0 ℃,3~4个月的气温低于-10 ℃;青藏高原南部（喜马拉雅山北坡—冈底斯山南坡）和中部（冈底斯山北坡—唐古拉山南坡）是高原的温暖区,全年有5个月的气温能达到5~10 ℃,有3个月的气温能超过10 ℃,尤其是拉萨—林芝—左贡一带在3500~4000 m以下的地区最冷月均温也能高于0 ℃。③ 北半球最高雪线和林线分别分布于高原的西南部和东南部,表明高原气温空间分布特征对本地的地理生态格局具有重要影响。

The spatial pattern of monthly air temperature of the Tibetan Plateau and its implications for the geo-ecology pattern of the Plateau

The immense and towering Tibetan Plateau (TP) acts as a heating source and shapes the climate of not only the Eurasian continent but also the entire world. Currently, air temperature of the plateau is usually obtained from discrete meteorological observational data using a series of statistical analyses and spatial interpolation. However, the interpolation accuracy is low due to the scarcity of meteorological observation stations, and little is quantitatively known about the detailed temperature pattern of the TP. According to Modis-based estimated air temperature data, this paper firstly studies the detailed spatial pattern of air temperature of the TP; Then it analyzes the spatial changes of isotherm altitudes of -10℃, -5℃, 0℃, 5℃, 10℃ for every month. Isotherm altitudes are extracted from Aster GDEM; Thirdly, this paper discusses the implication of air temperature of TP for treelines and snowlines based on 148 snowline data and 267 treeline data. The results show that: 1) isotherms have a trend of rising from the eastern and northeastern edges of the plateau to the interior and about 500-2000 m higher in the interior than in the eastern and northeastern edges; 2) the northwestern plateau, or the Qiangtang plateau and the Hoh Xil region, are the coldest regions of the TP, where air temperatures are below 0℃ for seven months and lower than -10 ℃ for three or four months in a year; the southern and central plateau, especially the north flank of Himalaya - the south flank of Gangdisê Mts., the north flank of Gangdisê Mts. - the south flank of Tanggula Mts., and the great river valleys, are quite warm, with monthly mean air temperatures between 5-10 ℃ for five months and above 10 ℃ for three months in a year; especially, air temperature of the coldest month is above 0℃ below the elevations of 3500-4500 m at Lhasa, Linzhi and Zuogong. 3) The highest treeline and snowline of the Northern Hemisphere are distributed in the southeastern and southwestern parts of the plateau, respectively, revealing a significant effect of air temperature on the geo-ecological pattern of the TP.