关键词: 极端气候, 年际变化, 周期变化, 祁连山及河西走廊

Abstract: Under the condition of global warming, the frequency of extreme climate and damage of meteorological disasters are increasing. Based on daily temperature and precipitation data of 20 weather stations in the Qilian Mountains and Hexi Corridor from 1960 to 2009, the interannual change trends of climate extremes were studied by methods of regression analysis and five years moving average, and the spatial distribution characteristics of interannual change trends and its significance of climate extremes were analyzed by method of Spline interpolation under ArcGIS environment, and the cycles of climate extremes were discussed by method of Morlet wavelet analysis under Matlab environment, so as to bring scientific accordance for local governments to deal with climate change and disaster prevention and alleviation. The results indicate the annual number of extreme high temperature days (EHTD) is on the significant rise by the rate of 0.79 d/a, and the trend of interannual change of EHTD is accelerative by larger waving scale after the middlelate of 1980s, especially the rate of EHTD getting higher after the middlelate of 1990s. This is contrary to the extreme low temperature days (ELTD), the annual number of ELTD is decreasing significantly by the rate of -0.54 d/a and the trend of interannual change of ELTD is reducing by larger waving scale after the middlelatte of 1980s, and the rate of ELTD is lower after the middlelate of 1980s. The annual number of extreme precipitation days (EPD) is increasing significantly by the rate of 0.02 d/a, and the trend of interannual change of EPD is rising by larger and smaller waving scale before and after the middle of 1980s respectively, but the trend became contrary after the middlelate of 1990s, and the rate of EPD is higher after the middle of 1970s. The spatial distribution characteristics of interannual change trends and its significance of climate extremes have some differences, but the response to the global climate change is consistent. The changing scale of annual number of extreme temperature and precipitation days in the Qilian Mountains is larger than that in Hexi Corridor, which indicates that the response to global climate warming in high altitude areas is more sensitive than that in low altitude areas. The changes of EHTD and ELTD are with obvious cycle by the time scale of 8 a and 22 a, and the cycle change of 22 a is the first main cycle. The changes of EPD are with obvious cycle by the time scale of 8 a, 10 a and 22 a, and the cycle change of 22 a is the first main cycle. Under the cycle change of 22 a, it is speculated that the annual number of EHTD and EPD will increase in the future of about 11 a after 2010, but ELTD will get into an opposite situation, which suggests that the rate of high temperature and heavy rain disasters will rise. From the cycle change step of 22 a, the variation trend in EHTD and EPD is consistent, but the variation trend in EHTD and ELTD is contrary.

Key words: climate extremes, interannual change, cycle change, Qilian Mountains, Hexi Corridor