摘要
文中利用EOF和SVD方法分析了近半个世纪中国春季沙尘天气频数的时空分布特征及其与近地面风速和海平面气压的关系。中国北方大部分地区春季沙尘天气发生频数近半个世纪呈减少趋势 ,2 0世纪 70年代末以前沙尘天气发生频数较多 ,70年代末开始逐渐减少 ,1997年降到最低值 ,同期中国近地面风速也呈减小趋势 ,两者之间存在显著相关。春季海平面气压场与中国沙尘天气的发生频数有十分密切的联系 ,海平面气压在中高纬度地区降低 ,中低纬度地区升高 ,气压梯度发生改变 ,从而引起地面风速减小 。
Using the methods of EOF and SVD, the spatial and temporal characters of spring dust storms in China and its associations with surface winds and sea level press ures in recent half century have been studied. In most part of China, the sprin g dust storms have the same trends. The dust storms have shown a decreasing trend in t he recent half century. Dust storms occurred more frequently from 1957 to late 1 970s. However, since the end of 1970s they have decreased and reached the lowest point in 1997. But in latest years the dust storms increased slightly. The spring surface wind speed in China has also illustrated a decreasing trend durin g the recent half century. There are significant correlations between dust storm s and surface wind speed. The surface wind speed has impact on the frequency of dust storms directly. The surface wind speed and dust storms have both shown a d ecreasing trend in recent half century. In 1997, the wind speed and dust storms both reached the lowest point. Since 1997, the wind speed has increased slightly and the dust storms have also increased. The sea level pressures in spring are closely related to dust storms and they have effects on the dust storms ultimate ly. During the recent half century, the sea level pressures have decreased at th e mid high latitudes while increased at the mid low latitudes which leads to t he change of pressure gradient. The surface wind speed has decreased because of the change of pressure gradient and this has eventually resulted in the decreasi ng of sand storms. Furthermore, the contrary changes of sea level pressures in n orth and south parts of China and over ocean and land have close correlations wi th the local variations of dust storms.
出处
《气象学报》
CAS
CSCD
北大核心
2004年第1期96-103,共8页
Acta Meteorologica Sinica
基金
国家重点基础研究发展规划"我国生存环境演变和北方旱化趋势预测研究"(G 1 9990 4 34 0 5)
