民勤绿洲1971—2010年沙尘暴特征及影响因素分析

Variation Characteristics of Sandstorm from 1871 to 2010 over Minqin Oasis and Its Cause

根据1971—2010年民勤近40 a气象资料、民勤周边县市沙尘暴资料,详细分析了民勤绿洲沙尘暴变化特征及影响因素,结果表明:(1)绿洲以局地性沙尘暴为主,但区域性沙尘暴无论是持续时间、伴随的大风强度和成灾性均大于局地性沙尘暴。(2)一日中局地性和区域性沙尘暴主要出现在下午和傍晚;月际除3月外其它月局地性均较区域性沙尘暴多,6—8月偏多明显,各季局地性均比区域性沙尘暴多,夏季偏多明显;年际局地和区域性沙尘暴均呈显著减少趋势,年代际为明显减少趋势。(3)干旱气候、丰富的沙源是民勤多沙尘暴的自然原因,气候的变化和下垫面状况的改善使局地和区域性沙尘暴均减少。

Based on the meteorological data from Minqin and vicinity from 1971 to 2010, sandstorm variation characteristics and its influencing factors over Minqin oasis are analyzed. The results show as follows. （1）Sandstorms over Minqin oasis were mainly local sandstorms, but persistence, gale intensity and disaster degree of regional sandstorms are greater than local sandstorms. （2）Regional and local sandstorms mainly appeared in the afternoon and evening; local sandstorms occurred more than regional sandstorms in each month （except March）, obviously more from June to August and for seasons, especially more in summer; regional and local sandstorms＇ annual and inter-annual trend was down significantly. （3）The natural causes of frequent sandstorms over Minqin oasis are arid climate and abundant sand source and the decreasing of regional and local sandstorm days is due to the climate change and improved underlying surface.