拉萨一次浮尘天气过程分析

Analysis of a Dust Weather Process in Lhasa

2007年1月15—17日拉萨地区出现了一次浮尘天气,造成空气质量污染,能见度下降;拉萨地区的生产、生活及交通运输受到了较大影响。应用欧洲中心客观分析场资料和逐日观测资料,主要从天气形势和气候特征分析了拉萨浮尘天气形成的原因和空气污染的局地气象条件。结果表明,由于冷暖空气在高原地区对峙,温度梯度和锋区加强;以及200hPa高空西风急流的影响,引发西藏地区大风,使干燥、疏松的地表形成扬沙、沙尘暴,大量的细小沙尘粒子随高空偏西气流携带至拉萨。加之拉萨本地低空处于弱辐合区,大气层结稳定,风速较小或静风,导致了拉萨浮尘天气形成。最后,给出了拉萨浮尘天气预报的思路,为拉萨浮尘天气的准确预报提供了一些参考信息。

From January 15 to 17,2007, a dusts weather process occurred around the region of Lhasa, which caused the pollution of air and the decrease of visibility. It brought bad influence to the Lhasa＇s production, transportation and resident life. The weather and climate characteristics are analyzed to depict the local meteorological conditions which cause the dust and air pollution. The results indicated that the causes of the dusts were the hot air confronted cold air on the plateau region, temperature gradient and front increasing. The strong wind blew in the western region of Lhasa and arose the floating dusts from the dry and incompact surface land. A great deal of thin sand in the weak convergence zone went to Lhasa along with the western high-level air current. Meanwhile, the Lhasa＇s local low altitude had the steady atmosphere layer and weak wind. This weather and orographic conditions are favorable to the invasion of floating sand, which caused the dusts breaking out, air polluting and visibility decreasing. Finally, some ideas are put forward for the forecast of dust weather in Lhasa.