摘要
民勤沙区 1 998年以来发生的 44次沙尘暴的观测研究结果表明 :( 1 )在民勤沙区每年春季 4月份是一年当中沙尘暴发生的高峰期 ,下午 1 4时左右和 1 8时左右是在一天当中沙尘暴发生的两个高峰时段 ;沙尘暴持续时间多在 2 h之内 ,最长的超过 6h;能见度 <50 0 m和≥50 0 m的各占一半 ,持续时间长则能见度小 ;沙尘暴的最大风向以 NW和 WNW占绝大多数 ;沙尘暴最大风的风速多在 2 0 m/ s以上 ,最大 2 5.2 m/ s。 ( 2 )沙尘暴的发生存在着一个或长或短的发育过程。在民勤沙区 ,沙尘暴发生前期在气温、气压、风速、风向等气象因子方面表现出明显的预兆 ,根据这些前期气象因子方面的异常特征就可以对沙尘暴进行预测、预报和预防。( 3 )在民勤沙区冬季 1 2～ 1月份的沙尘暴不仅持续时间较短 ,而且在前期气象因子方面与其他季节的沙尘暴有明显不同。 ( 4)沙漠地区主要天气现象的前期特征比较明显 ,但其表现过程比较短促。因此 ,根据沙尘暴前期气象因子的异常特征只适合对沙尘暴的发生时间。
The observations and the analyzes of 44 times of sand storms since 1998 showed that:(1)On Minqing sand areas,the frequently occured sand storms were in April in a year,and at about 14 to 18 oclock in a day.Usually they continued about 2 hours,and the longest one was over 6 hours.The sand storms in which the visibility was less than 500m took about 50% of all sand storms.Generally,the visibility was little when the continued time of sand storm was longer.The directs of the most strong wind were NW and WNW,The speeds of most of sand storms were about 20m/s,and the strongest one was 25.2m/s.(2)The occurrency of sand storm has a longer or shorter course.On Minqing sandy areas,the factors,such as temperature,wind speed,wind directs and so on,displayed clear signs of coming of sand storm,and according to them,the sand storm could be calculated,forecasted and prevented.(3)Durring December to January,the sand storms were shorter in time,and the earlier stage meteorological factors were different from other seasons.(4)In sandy areas,the main weather phenomenons in earlier stage were obvious ,but the courses were short.So,according to the signs mentioned,the time of sand storm occurrence,visibility and duration could be forecasted only with in short-term. \ \
出处
《干旱区资源与环境》
CSSCI
CSCD
2002年第2期107-111,共5页
Journal of Arid Land Resources and Environment
关键词
分布特征
沙尘暴
前期特征
气象要素
民勤沙区
Sand storm, earlier stage features, meteorological Factors, Minqin sand areas
