【摘要】 应用1971—2016年河西走廊东部代表站的地面观测资料、NCEP 2.5°×2.5°月均地面至300 hPa高空资料,2006—2016年民勤逐日07和19时每隔10 m加密高空资料,分析了近45年河西走廊东部冬季沙尘暴天气的年际变化特征。同时选取2016年11月两次沙尘暴天气过程从天气学成因、物理量场及近地面边界层特征等方面进行了诊断分析。结果表明:近45年河西走廊东部冬季沙尘暴日数呈减少趋势,产生大风沙尘天气的主要原因不仅与大型冷暖空气强度及环流形势有关,还与冷锋过境时间、日变化、近地层风速和干湿程度关系密切。夜间至早晨近地面逆温厚且强,大气层结稳定,削弱沙暴强度,而午后到傍晚,逆温薄而弱,大气层结不稳定性强,加强了动量下传和风速,增强沙暴强度。近地层越干,风速越大,沙暴越强。更多还原

【Abstract】 Based on the surface observation data from the representative station over eastern Hexi Corridor,the NCEP 2.5°× 2.5° monthly average upper-air sounding data from surface to 300 hPa during 1971—2016,and the daily upper-air densely observed data every 10 m at 07:00 BT and 19:00 BT from 2006 to2016 in Minqin,the inter-annual variation characteristics of winter sandstorm over eastern Hexi Corridor in recent 45 years are analyzed.At the same time,the synoptic causes,physical quantity field and nearsurface boundary layer characteristics of the two sandstorm processes in November 2016 are also analyzed.The results show that the number of winter sandstorms over eastern Hexi Corridor has decreased in recent45 years.The main causes of strong wind and dust weather are not only related to the intensity of largescale cold and warm airs and circulation situation,but also closely related to cold front transit time,diurnal variation,wind speed and humidity near the surface.Near surface,the temperature inversion layer is thick and strong from night to morning,atmospheric stratification is stable,which weakens the strength of sandstorms,but surface inversion from afternoon to evening is thin and weak,strengthening the atmospheric instability,momentum down propagation and wind speed,thus further enhancing the strenght of sandstorms.The drier the surface layer,the faster the wind speed,and the stronger the sandstorm.更多还原