石羊河流域1959年至2008年风速变化特征分析

利用线性拟合、Mann—Kendall方法、小波分析对石羊河流域五个测站空间平均的近50年来的逐日风速资料进行了倾向、周期、突变等特性分析。研究结果表明：1959年至2008年间，整个石羊河流域风速呈减小趋势，变化率约为-0．004m／（s．a）．而上游风速呈现明显的上升趋势。四个季节中冬季风速降低速度最大，而夏季风速呈现上升趋势。风速的长期变化还具有一定的突变性，年平均风速在1988年出现了由高到低的突变，表明风速开始下降。复值Morlet小波分析的结果显示，风速变化存在6a、13a、19a、25a四个峰值。其中19a的时间尺度为第一主周期。

Wind Velocity Variation from 1959 to 2008 in the Shiyang River Basin

The spatial-temporal dynamics of wind velocity are essential to climate change research and terrestrial water cycle, as it is a crucial driving force for evapotranspiration （ET）, and is also closely related to the fully realization of clean energy target. In order to investigate the variation characteristics of wind velocity on the Shiyang River Basin, the daily wind velocity data from 5 stations in the Shiyang River Basin over the past 50 years were collected and analyzed by using the methods of linear regression （taken time as an independent variable）, wavelet analysis and Mann -Kendall test. The results showed that a significant declining trend of wind velocity existed in the study region during the period of 1959 to 2008, at the rate approximately -0.004m/（s.a） .This was in accordance with the research result of the declining rates in middle latitude countries ,within range of -0.004m/（s.a） to -0.017m/（s.a）.Furthermore, the declining process mainly took place in 1988a. Linear regression results demonstrated that wind velocities in the four seasons were all statistically significant at the level of 0.05, with values of -0.0019 m/（s.a）,0.OO04m/（s.a）,-0.0012 m/（s.a）,- 0.003m/（s.a） from spring to winter. Wind velocity in winter exhibited the most significant declining trend with the highest declining rate. Abrupt change was found in the long-term climate variation. The results showed that on an annual wind speed basis, the year of 1988 can be viewed as turning point of the ahrnpt change. Complex Morlet wavelet analysis revealed that seasonal wind velocity exhibited quasi-periodic variations of around 6a, 13a, 19a and 25a years, 19a was most obvious.