2004年春季沙尘天气分析

Cause Analysis of Dusty Weather in Spring 2004

利用全国673个站每日8个时次的地面天气报告资料和T213模式产品，分析了2004年春季我国沙尘天气的主要特点，并初步揭示了其成因。结果表明：2004年春季我国北方共出现了15次明显的沙尘天气过程，其中3月相对偏多，4月却明显偏少；沙尘天气过程的强度大多偏弱。原因在于2～4月上中旬我国北方主要沙尘源区气温持续偏高，降水偏少，地表疏松，沙尘天气所必需的物质条件充足；同时，3月冷空气频繁影响我国北方，沙尘天气相对较多，但由于大部分冷空气势力不强，影响时间短，所引发的沙尘天气过程较弱。4月上中旬，影响我国北方的冷空气势力明显偏弱，激发沙尘天气的动力条件不足，因而沙尘天气显著偏少。

The temporal and spatial distribution characteristics of dusty weather in China in spring 2004 are analyzed on the basis of the data from surface synoptic maps （8 times per day） and T213 model products. The results show that there were 15 major dusty weather processes, more in March and less in April and May, and most of them were weak. Further research shows that because the temperature was higher and the precipitation was less than the normal value in the earlier months, the soil moisture was less and the soil surface was drier in spring in the northern China. When the cold air attacked North China frequently in March, more dusty days and severe dust storms occurred. After March, the dusty weather events decreased quickly because of less cold air activities and weaker dynamic condition.