Climatic Variation Over Qilian Mountain Region In Last 50 Years

Qilian Mountain was one of important mountains in Northwest China. Qilian Mountain region was located in convergence of two major natural areas, arid areas in Northwest China and the Qinghai-Tibet Plateau area.This feature made work of climate research on the Qilian Mountain have a typicalness. As an important geographic and climatic dividing line, Qilian Mountain occupied a very important geographical position in China. There were 3300 pieces of glacier in the Qilian Mountains, these glaciers downstream water was the birthplace of rivers in Hexi region, which supplied a large part of the river from the Qilian Mountains glacier melt water. Qilian Mountain was a large and comprehensive eco-system, between 2500~3000m the slope of Qilian Mountain were large tracts of virgin forest and grassland that constituted Qilian Mountain unique water conservation forest. These forests were between the "ice reservoir sources" and the river water which played important role in soil and water conservation, increasing water, regulating climate. So, climate change research of the Qilian Mountain region was significance.Using annual mean, maximum, minimum, air temperature and monthly mean precipitation data from 18 weather stations in Qilian Mountain region from 1960 to 2005. climatic liner trend, accumulated variance analysis and Mann-Kendall trend methods, the trend of temperature and precipitation were analyzed. Then abrupt of temperature and precipitation was analyzed by the Mann-Kendall abrupt analysis. Doing periods analysis of temperature and precipitation used the wavelet analysis. At last the comparative analysis of temperature and precipitation between Qilian Mountain and other place was done.The main findings can be summarized as follows: in recent 46 years, there was an obvious ascending trend for the interannual variation of air temperature. The average temperature, minimum temperature, maximum temperature of the tendency of the rate of temperature are as follows: 0.29℃/10a, 0.240℃/10a, 0.4℃/10a,the range of temperature: minimum temperature> average temperature>maximum temperature.The rates of Spring, Summer, Autumn, Winter were 0.34℃/ 10a, 0.191℃/10a, 0.155℃/ 10a, 0.457℃/ 10a. Temperature changes had about 23a, 11a, 5a periods. The abrupt time of temperature in Qilian Mountain lag behind global, orth hemisphere and Northwest of China. In recent decades, precipitation change had large varied amplitude. Increased precipitation trend was showed in the fluctuations. Climatic trend rate of annual precipitation was 5.902mm/10athe statistically significant reached 0.05. climatic trend rate of annual precipitation for every season was 0.846mm/10a,3.905mm/10a,1.345mm/10a,0.287mm/10a. the abrupt time of temperature lag behind precipitation, precipitation changes had about 8a, 5a, 17a, 23a, 12a and 2a periods.