干旱区生态环境知识资源中心

The origin of the September 2001 dust episode around the Baltic Sea was estimated by a model study to be the Ryn Peski desert of Kazakhstan. Some of the coarse particles came from Estonian-Russian sources where oil shale is used. Although the correlation of the high wind velocity over this desert with a corresponding weather system and the south-eastern flow is rather high, similar events can occur frequently. Deposition is small, because those weather situations are rather dry. By assessing long-term natural dust pollution of Scandinavian territory it is shown that the Caspian Sea desert influence on aerosol concentrations is about an order of magnitude higher than that of Sahara. Strong seasonal variations are caused by three main factors - frequency and intensity of dust storms in the desert, simultaneously prevailing wind direction, and washout intensity along the transport route. The overall maximum of dusty days occurs during March, and the minimum over the summer months.