近13年内蒙古地区沙尘暴的分布特征

Distribution characteristics of sandstorm in Inner Mongolian Area in the past 13 years

利用1995—2007年13年内蒙古地区118个地面测站的沙尘暴、能见度、风速风向观测资料，确定了不同范围、不同强度沙尘暴标准，给出了特强、强、次强和弱沙尘暴日的个例谱；对地理分布、时间分布特征进行分析。结果表明：近13年内蒙古地区有5个沙尘暴多发中心，强和特强有2个高发区。年变化显著，1995年沙尘暴开始减少，1999年开始增加，2001年达到最多，之后开始减少，2003年沙尘暴次数最少，2004年开始呈波动增加趋势。在一年内，沙尘暴、强和特强沙尘暴集中出现在春季的3～5月份，4月份最多，沙尘暴下旬相对集中，上、下旬是大、小范围强和特强沙尘暴易发时段。

Based on 13 years＇ observation data of the sandstorm, the visibility, the wind speed and the wind direction in 118 ground survey stations in Inner Mongolian area from 1995 to 2007, the standards of sandstorm of different ranges and different intensities were confirmed, every single spectrum of extra - heavy, heavy, sub - heavy and weak sandstorm were provided, and the characteristics of geographical and time distributions were analyzed. Results showed that during the past 13 years, there were 5 centers where sandstorm occurred frequently, and respectively tw9 centers of extra - heavy and heavy sandstorm in Inner Mongolian area. Furthermore, the sandstorm varied remarkably from year to year. From 1995, it began to decrease, but from 1999 it started to occure quite frequently and reached the maximum in 2001. And then, the number of sandstorm reached the minimum in 2003, and it started to take on the increasing tendency from 2004. During a year, sandstorm, heavy and extraheavy sandstorm happened frequently in March, April and May in spring, and among them, it happened most frequently in April. For every month, sandstorm occurred frequently in the third ten days. Moreover, extra - heavy and heavy sandstorm of small and wide scopes then occurred frequently in the first and third ten day in a month.