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• CN 62-1072/P
• ISSN 1000-0240
• 创刊于1979年
• 主管单位：中国科学院
• 主办单位：中国科学院寒区旱区
•                  环境与工程研究所
•                  中国地理学会

• 研究论文 •

### 天山博格达山脉的自然地理特征及冰川发育的气候条件

1. 1. 兰州大学;
2. 日本山口大学教育学部;
3. 中国科学院新疆地理研究所
• 出版日期:1984-11-25 发布日期:2012-04-26

### Physical Geographic Features and Climatic Conditions of Glacial Development in Bogda Area, Tian Shan

Wu Guanghe1, Yutaka Ageta2, Qiu Jiaqi3

1. 1. Department of Geology and Geography, Lanzhou University;
2. Yamaguchi University, Japan;
3. Xinjiang Institute of Geography, Academia Sinica
• Online:1984-11-25 Published:2012-04-26

Abstract: Bogda is one of the important component parts of the Chinese Tian Shan, located between 43°10’-45°5’ N and 87°40’-91°35/ E, having a general strike from east to west with its middle section as an arc pointing southward. Tectonically it is an anticlinorium of the late Caledonian or Early Variscian foldbelt of the Tian Shan geosyncline with the property of a fold-block mountain. Difference in tectonic movements of the basins on both sides of the mountains makes the southern and northern slopes obviously asymmetric and terrace-structured. Its highest peak, Mt. Bogda, 5445 metres a. s. 1., is located at the western end of the Bogda mountain range. Its altitude lowers continuously from west to east. In its eastern section, the mountain range is in medium size.There are about 50 rivers in the Bogda area disbursing asymmetrically on both sides of the ridge in dendritic shape. Rivers are all short and their gradient is steep with a total runoff of about 1700 million m3. Some rivers on the southern slope dissect through the ridge and make the divide line move northward, thus decreasing the difference in runoff on two sides. Longitudinal valleys develop in the upper reaches of Kaikeng river, Mulei river and others, widening their drainage basins in the high altitudes with the richest precipitation. Therefore, the biggest river is not located in the vicinity of main peak but in the middle section on the northern slope.Modern vegetation and soil of Bogda mountain range developed in the process of glacial retreat since the end of late Pleistocene. Northern slope of the mountain range shows vertical natural landscape zones as follows: alpine ice and snow, alpine sub-glacial, alpine meadow-steppe, mountain forest, and mountain steppe, taking desert zone as their faundamental zone. Forest zone is absent on the southern slope of the mountain range where desert zone went up to about 1800 metres above sea level and became a part of the vertical zones.The variation of latitudinal zonality in temperature gives the Bogda Area a more favorable low temperature condition necessary for glacial development than other mountains in west China except for the Altay. Therefore. the altitude of glacial distribution in the Bogda is lower than that in all the other mountains. But because of the effects of unusual heat in the Turpan Basin on its southern side and of inversion layer in the Junggar Basin in winter on its northern side, the rate of vertical decrease in temperature is rather small, and the annual average of 0℃ isotherm being uplifted by 800 m. The snowlines are correspondingly higher as well. Therefore the "altitude span" of the high mountain glaciation has been reduced and the scale of glaciation also restricted.The Bogda range is situated in the belt-shaped rainy area of central Xinjiang with a precipitation much more aboundant than that in the dry basin on its both sides and increasing with altitude. The maximum rainy belt is situated in the high mountain area above 3500 m.At above 3900 m on the northern slope and 4000 m on the southern slope, the average annual temperature is below -9℃ and the average monthly temperature from June to August is below zero. The annual precipitation is 670 mm, all in solid state. Such combination of heat and moisture in low temperature semi-humid pattern already satisfies glacial development, but far from optimum condition. The Bogda mountains with a strike from east to west and a precipitation source mainly from westerlies and north-westerlies obtain heat and moisture for glacial development favourable on the northern slope, but unfavourable on the southern slope, reflecting greatly the pattern of glaciation on the southern and northern slopes, both in number and in scale and well as in other respects. But in the region of Bogda peak, the relief condition offsets partly this difference.