近50年来祁连山及河西走廊极端气温的季节变化特征

Seasonal Characteristics of Extreme Temperature Changes in Qilian Mountains and Hexi Corridor During Last Fifty Years

利用1960～2009年的日平均气温资料,采用线性趋势、Morlet小波分析、Mann-Kendall法对祁连山及河西走廊极端气温的季节变化特征进行了分析。结果表明:各季节极端高温天气呈显著增多趋势,极端低温天气呈显著减少趋势;各季节极端气温天气的变化周期略有不同,春、夏、秋、冬季极端高温天气的主周期分别为8、14、16、16 a,极端低温天气的主周期分别为14、16、14、6 a;春、夏、秋、冬季极端高温天气分别在2002、1997、1994、1986年突变增多,极端低温天气分别在2002、1997、1987、1986年突变减少,秋、冬季极端气温天气对全球气候变暖的响应比春、夏季早。

Based on daily temperature data of 18 meteorological stations in Qilian Mountains and Hexi Corri- dor 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 win- ter 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 respectivelywith 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 ex- treme 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 disas- ters 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.