关键词: 极端气温, 周期变化, 气候突变, 祁连山, 河西走廊

Abstract:

Based on daily temperature data of 18 meteorological stations in Qilian Mountains and Hexi Corridor from 1960 to 2009, the seasonal characteristics of extreme temperature change were analyzed by methods of linear trend, Morlet wavelet and Mann-Kendall. The results indicate that extreme high temperature days in each season are on the rise significantly, especially increased with larger scales after the middle of 1980s. But that is contrary to extreme low temperature days, which decreased with larger scales after the middle of 1980s in spring and summer, and decreased after the middle and later of 1960s in autumn and winter. The changing scale of extreme temperature days is the largest in winter, and the changes of them are before ten years in winter than in other seasons, which indicated that the significant change of extreme temperature days took place in winter firstly. The cycle changes of extreme temperature days in different seasons are different, but they are grouped in 6-10 a、12-16 a and 18-22 a. The major cycle of extreme high temperature days in spring, summer, autumn and winter are changing respectively with 8 a、14 a、16 a and 16 a, and that of extreme low temperature days are changing respectively with 14 a、16 a、14 a and 6 a. The mutation of extreme high temperature days in spring, summer, autumn and winter increased in 2002、1997、1994、1986, respectively, but that of extreme low temperature days decreased in 2002、1997、1987、1986, respectively. Except autumn, the abrupt changes of extreme high temperature days and extreme low temperature days in other seasons are coincident. The response to global warming of extreme temperature days is earlier in autumn and winter than that in spring and summer. The change of extreme temperature days will bring some effect to the Qilian Mountains and Hexi Corridor. The increase of extreme high temperature days will add pressure of preventing fire for forest and grasslands in Qilian Mountains. The decrease of extreme low temperature days will reduce the occurrence frequency of freeze damage, but it will be contribute to destructive insect to crossing the winter, which will cause the disasters of plant disease and insect pest in forest, grasslands and farmland, and it will be a potential threaten for protection of ecology environment and agriculture production.

Key words: extreme temperature, cycle change, abrupt change of climate, Qilian Mountains, Hexi Corridor