关键词: 内蒙古地区, 沙尘暴, 强和特强沙尘暴, 标准, 特征

Abstract: The 13-years observation data (from 1995 to 2007) of sandstorm, visibility, wind speed and direction from 118 ground survey stations in Inner Mongolian area were used to configure the standards for sandstorms in different ranges and with different intensities. Besides, every single spectrum of extra-heavy, heavy, sub-heavy and weak sandstorm was provided, and the characteristics of dust-storm space-time distribution and climate factors distribution were analyzed. In these 13 years, In Inner Mongolian area there were 5 centers where sandstorms frequently occurred, and two centers where extra-heavy and heavy sandstorms occurred. The frequency of sandstorms varied remarkably from year to year. The number of annual days decreased from 1995, increased from 1999 and reached the maximum in 2001, again decreased since then and reached the minimum in 2003, and it fluctuated with increasing tendency from 2004. During a year, sandstorm, heavy one and extra-heavy one happened frequently in March, April and May of spring, with most in April. For every month, sandstorms mostly occurred in the third ten days, and the extra-heavy and heavy sandstorms, also the small scale and larger scale ones frequently occurred in the first and third ten days. Sandstorms frequently occurred in areas where the average ground temperature is higher than 5 ℃ and the average ground relative humidity is lower than 40% during the period from March to May.

Key words: Inner Mongolian area, sandstorm level, standard, characteristics