Creating Fields Of Equilibrium Line Altitude And Analyzing Their Space Distribution Characteristics In The Southern Tibet Glacier System

The southern Tibet glacier system is one of the most intensively, glaciers disturbed area in China, where glacier area amounts to 18101.9km² and accounts for more than 32% of the total glacier area in China. There is 1614.7102km³, accounts for 28.88% of the total glacier volume in China, and the number of the glaciers here is 13009, accounts for 28.12% of the number of glaciers in China. Many rivers' source originated in the southern Tibet, such as Nujiang River, Langcang River, Ganga Drainage, Yarlung Zangbo River. At the same time, there are the highest mountain in the world. The paper discusses the distribution of equilibrium line attitude (ELA) of glacier system and reveals the main factors in the region for its flourishing and development. The main results and detailed contents were revealed as following:(1) Based on the Glacier Inventory Database of Cold and Arid Regions Environmental and Research Institute, this paper analyzed the glacier distribution characteristics in details, by the parameters of glacier system's area ,volume, number, [H (ma)|—] , [H (me)|—] , [H (mi)|—] , and so on.(2) The article used the theory of mass balance and glacier system, the equation of calculating ELA_hc( calculated snow line ) can be obtained, based on the linear relationship between ELA_h and H_me. The more number of the data points in glacier system, the more sound linear relationship between ELA_h and H_me. So we used the linear relationship of the whole glacier system's, all the glaciers' ELA_hc can be resulted from the total linear relationship equation.(3) In order to dispel the influence of topographical snow-line and other uncertain error , a method is adopted that the graticule mesh of 10'×10' overlays the data points, and calculates arithmetic average value of all the data points' longitude, latitude and ELA_hc in every square, utilizing such software as Arc/GIS ,etc. Then a ELA_hc distribution map of the interval of 100m, namely the equilibrium line attitude field, is produced in ordinary Kriging interpolation.(4) Equilibrium line attitude of glacier system's distribution map, topography and river system map are showed in the same map. It is easy to find the relation of snow line, river, mountain range, etc, and four different distributions. At the same time, it can be found that this total trend of equilibrium line attitude of glaciersystem's rises progressively from west to east in the area. The ELA is the lowest near Nyingchi-Zayu, which is a typical monsoon ocean glacier. The middle area formed a continent .type glacier systems because Himalayas' high peaks impact on precipitation and temperature of the area. And a transitional type exists in the the place between the preview two. The western area inferior lives maritime glacier because its precipitation increases caused by west wind circulation and forms the second low value area.In a word, this district is a typical glacier system influenced by topography.