内蒙古两类持续型沙尘暴的天气特征

利用观测资料对内蒙古地区两种不同类型的持续型沙尘暴过程进行了对比分析,结果表明:天气系统的稳定少动是这两类沙尘暴在同一地区长时间持续的共同原因。在这2次过程沙尘暴的持续期,大气层结的日变化受到不同程度削弱。主要原因是沙尘气溶胶的辐射反馈效应。在冷锋型沙尘暴过程的持续期,地面风速出现的明显日变化加强了沙尘暴强度的日变化。而在高压底部型沙尘暴过程中,暖平流和中尺度低压辐合抬升产生的对流进一步削弱了层结日变化。这一因素以及期间地面风速的相对稳定使沙尘暴强度未发生明显改变。

The Characteristic of Weather Factors in Two Types of Sustained Dust Storm in Inner Mongolia

By using the observational data, a comparative study on the weather characteristic within the maintaining period of two different types of dust storm was conducted. The result shows that in these two cases the dust storms sustained for two or three days. It is due to the weather influence systems stood or moved slowly. The diurnal change of stratification was minimized in two different degrees. The common reason was the radiation of dust aerosol. In the Cyclone typical case, the intensity of dust storm exhibited an obvious diurnal change owing to the diurnal change of the strength of surface wind speed. In High Bottom case (the dust storm appeared at the bottom of the surface high), the meso-low (under 700 hPa) conducted a key influence on the dust storm through its induced ascending motion. It also contributed to the sustaining of mixed layer. Meanwhile, the surface wind speed also did not changed in the sustaining period of dust storm. And so in the High Bottom case the dust storm maintained with same intensity for more than two days.