【摘要】 文章通过对青藏高原北部马兰冰芯中1δ8O记录(主要反映暖季气温)与近几十年来高原中、南部气象台站暖季气温变化的对比分析,发现在年代际时间尺度上高原北部地区暖季气温变化与南部地区存在明显的差异,其分界线位于32°~33°N附近一带。该位置也是青藏高原地区气候、地理、地质、地球物理等方面存在南北差异的重要分界线。更多还原

【Abstract】 In the northern Tibetan Plateau,especially in the Kekexili Region and the Qiangtang Plateau,the sparsity of the meteorological observation data has limited researchers to investigate the temporal and spatial characteristics of climate changes over the whole Tibetan Plateau.Ice cores retrieved from these regions can supply information of the past climate changes,making it possible to compare the past climate changes in different regions of the Tibetan Plateau.In 1999,we drilled an ice core from the Malan Ice Cap in the Kekexili Region.Based on the record of(δ¹⁸O) in this ice core,past warm season air temperature variations have been reconstructed.Comparing the variations of(δ¹⁸O) in the Malan ice core and the summer half-year air temperature at Lhasa in the southern Tibetan Plateau,we found out that the variations of the warm season air temperatures on the decadal time scale were opposite at these two sites, encouraging us to compare tie record of δ¹⁸O in the Malan ice core with the warm season air temperatures in an array of meteorological stations from north to south of the Tibetan Plateau.It was found out that the boundary between the northern and southern Tibetan Plateau with different variations in the warm season air temperatures on the decadal time scale is at about 32°～33°N.This is also supported by the NCEP/NCAR reanalysis air temperature data.Interestingly,most atmospheric,geographical,geological and geophysical phenomena over the Tibetan Plateau match this boundary,for example,the average position of the shear line activity,the northward extending limit of the Indian monsoon,the south limit of the continuous permafrost region,the location of the Lake Bangong-Nu Jiang suture zone,the dividing line between the high and low geothermal heat fluxes,the dividing line between the old and young terranes,etc.It was presumed that the differences in summer atmospheric circulations,in surface permafrost conditions,and in geothermal heat fluxes in the northern and southern Tibetan Plateau might be responsible for the different variations in the warm season air temperatures in the northern and southern Tibetan Plateau on the decadal time scale.These also suggest that the Tibetan Plateau might be an ideal natural laboratory for studying the interactions among the Earth’s spheres.更多还原