2004年春夏季两次沙尘暴期间地面气象要素变化特征对比分析

Variations of Surface Meteorological Element during Twice Sandstorms Passing Jiuquan on March 28 and July 12 of 2004

用沙尘暴自动观测系统记录的每分钟地面气象要素,分析了2004年3月28日和7月12日发生在甘肃酒泉的两次沙尘暴过境时地面微气象要素的变化特征。结果表明:①两次沙尘暴发生前地面湿度都较小,气压较低,但是在临近发生时地面气压会猛增,接着维持一段时间的相对稳定状态,但春季沙尘暴过程这个时间更长;沙尘暴即将结束时地面气压再次大幅增加。②沙尘暴发生前气温偏高,结束后较短时间气温会出现急剧下降;春季沙尘暴期间0cm地温和气温的变化趋势比较一致,但是5cm地温的变化趋势与气温变化差别较大;夏季沙尘暴过程中0cm、5cm地温的变化趋势与气温变化趋势都比较一致。③由于下垫面性质的差异,春季发生的这次沙尘暴地面水平风速明显比同年夏季发生的沙尘暴大,但水平能见度却比夏季发生的沙尘暴好。

Based on the per minute surface meteorological element data of the twice sandstorms cases recorded by sandstorm automatic observation system of Jiuquan base station on March 28 and on July 12 of 2004,the micro meteorological element change characteristics were analyzed.The result indicated that： ①The surface humidity and barometric pressure were both quite low before sandstorms.Surface pressure increased suddenly in the beginning course of the twice sandstorms,then maintained a period of relatively steady states.But the relatively steady period was longer in the spring sandstorm case than that in winter sandstorm case.The surface pressure largely increased once again before sandstorms nearly finished.②The surface air temperature was high before sandstorms happened,but decreased quickly at the end of the course.In the spring sandstorm period,the 0 cm depth earth temperature and surface air temperature change tendencies were quite consistent.But in summer not only the 0 cm depth earth temperature but the 5cm depth earth temperature variation was consistent with surface air temperature change tendency.③Owning to the difference of the surface characters in different seasons,the horizontal visibility of summer case was bad than the spring courses,although the horizontal wind speed of the spring occurs was obviously bigger than that of the summer sandstorms.