陕北地区沙尘暴天气分析及预报

分析了陕北1960_2000年沙尘暴的年际和年代变化情况。从高空环流形势图上，可将该地区沙尘暴天气的影响系统分为三种类型。研究发现：陕北沙尘暴的产生不仅受强风、大气的不稳定和沙源三大因子支配，前期的干旱程度也是产生沙尘暴的一个重要因子。用降水和气温这两个要素构成的干旱指数S的变化与陕北沙尘暴的变化趋势基本一致。通过检验可以发现，充分考虑该地区前期干旱指数S的变化，将会明显提高强沙尘暴的预报准确率。

Sandstorm Weather Analysis and Forecasting in North Shaanxi

This paper analyzed the interannual and decadal changes of sandstorm from 1960 to 2000 in north Shannxi.According to the upper air circulation pattern,we divided the impacting system on sandstorm weather of this region into three patterns.Sandstorm occurring in north Shaanxi was not only influenced by strong wind,thermal instability and sand source,but also by the drought degree of previous period,an important factor to sandstorm occurring.The change of drought index that is composed of precipation and air temperature accorded with the change tendency of sandstorm occuring in this region.Through application test,we found out that the accuracy of sandstorm forecast could be improved if we take the prophase change of drought index into consideration.