TREND SURFACE ANALYSIS OF THE EXISTENT SNOWLINE IN WEST CHINA
Jiang Zhongxin (The Second Institute of Railroad Survey and Design)
The analysis of twenty five existent snowline elevation values in west China indicates that snowline elevation H (meter) presents zonality change declining from south to north with latitude φ(degree) and the change dec- lining from west to east.with longitude,which relates to distance L (kilo- meter) to east coastline.Therefore,first order trend surface equation of the snowline in west China is: H=7800+0.444L-110φ Its goodness of fit is 82.53%.The equation shows a plane inclined southwest to northeast.Second order trend surface equation of the snowline in west China is. H=2.957L+554.9φ-0.0001151L~2-0.05354Lφ-6.991φ~2-7555 Its goodness of fit reaches 93.39%.The equation represents really distribu- tion law of the snowline in west China.Its form resembles a "overturning anticline" from southwest to northeast.The "raised axis" seems to be supe- rimposed upon first order trend surface,which reflects the effect of relief. The snowline elevation in west China depends on horizontal zonality,the distribution of ocean and land,and the relief.