近45a我国沙尘暴和扬沙天气变化趋势和突变分析

利用1954-1998年我国334个站每月沙尘暴和扬沙发生日数资料,通过线性趋势估计和多项式函数拟合等方法分析了沙尘暴和扬沙日数的长期趋势变化和周期变化,发现沙尘暴和扬沙日数的总体趋势是下降的,沙尘暴和扬沙年平均日数都是在20世纪50年代最高,60年代减少,之后70年代又有回升的趋势,到80年代又减少,90年代最少。沙尘暴日数的变化存在着6.7a的周期及2.59a和3.38a的周期,并且2.59a和3.38a的周期都通过了α=0.1的显著性检验。扬沙不存在显著性周期。由于资料长度的限制,无法对22a以上的长周期进行分析。利用滑动t检验法和气候跃变参数J_y分析了沙尘暴和扬沙日数的突变问题,发现沙尘暴和扬沙日数从80年代到90年代的变化率最高,沙尘暴和扬沙分别在1985年和1984年发生了由多到少的突变。我国北方强沙尘暴的发生次数从50年代到90年代呈上升趋势,从而使沙尘天气对我国的影响不但没有减弱反而有增强的趋势;近年来,大范围的强沙尘暴天气出现的频率增加、程度增强、范围扩大,因此保护生态环境,防止土地荒漠化,是我们目前面临的紧要任务。

Analyses of Sandstorm and Sand-blowing Weather Trend and Jump in China in Recent 45 Years

Based on the meteorological date from 334 stations in China during 1954\_1998,the temporal and spatial variation characteristics of sandstorm and sand-blowing weather are studied.The results are as follows:(1) sandstorm and sand-blowing weather had an obviously inter-annual change in recent 45 years.In total,the days of sandstorm and sand-blowing weather decreased with time in China.Both the minimum of the number of the days and the maximum of the relatively variational rate emerged in 1990's.(2) In the past 45 years,sandstorm had the oscillation period of 2~3 years.An obvious jump of the days of sandstorm and sand-blowing weather respectively occurred in 1985 and 1984.(3) There was an increasing trend of frequency of strong sandstorm from 1950's to 1990's,so the harm of sandstorm and sand-blowing weather to our society also became seriously.It is very necessary to protect environment and control desertification for decreasing the days and degree of sandstorm and sand-blowing weather.