Establishing the field of equilibrium line altitude of the glacier system in the Chiangtang Plateau based on geographic information system and its distribution characteristics
The Equilibrium Line Altitude(ELA h) could comprehensively show the development of glacier is influenced by topography,terrain,climate and so on,which acts as an important indicator of mass balance and environment in the glacier area.The change of ELA h can induce glacial fluctuation correspondingly,and lead to varies of glacial melt water and sea-level.ELA h of the Chiangtang Plateau,Tibet is highest in China,the high-low elevation generally between 5 700-6 000 meters.So the study of distribution and variation laws of Equilibrium Line Altitude of the glacier system the Chiangtang Plateau not only is of profound theoretical significance,but also provide basis for man-land relationship,resource utilization,ecology environment and social economy sustainable development in the cold and arid regions.According to the linear relationship between the Equilibrium Line Altitude(ELA h) and the mean height(H me) in the Glacier System of the Chiangtang Plateau,the calculated equilibrium line altitude(ELA hc) can be obtained.The calculated result indicates that the measured ELA h value and are close to the ELA hc value.Their difference value is only 0.16 m,which means that it is credible calculating equilibrium line altitude by this method.By comparison,it is found that the field of Equilibrium Line Altitude of the Glacier System established by group average is more beautiful and regular than the one without group average.The distribution characteristics of the Glacier System'EL hc Ain the Chiangtang Plateau are as follows: ELA hc gradually descend from the south to the north and ascend from east to west.In general,they are in a gradually decreasing process from southwest to northeast,which do not alter too much,and most of them are above 5 700 m.However,the highest value is not located in southern part of the highest temperature and northwestern part of the least precipitation,but situated in Longger Mountain.Even individual glaciers in Longger Mountain reach up to 6 000 m or more,which not only is highest in the study area and Qinghai-xizang Plateau Interior Area,but also in the northern hemisphere.Another three high value areas are around Bobogawufeng,Tuzegangri and Zangsegangri,and the minimum value lies in Jinyanggangri.The result is rationalized by combination of both decreases of precipitation from southeast to northwest and temperature from south to north,reflecting the vapor in the air coming from southwest monsoon through the path of southwestern Xizang(Tibet).