Abstract: Based on the dust weather data observed by 60 meteorological stations in Liaoning Province during the period from 1971 to 2005,in this paper the interdecadal and seasonal change,spatial distribution and impacts of dust weather including floating dust,blown sand,sandstorm and dusty weather in Liaoning Province are analyzed.The results are as follows:(1) Interdecadal change of dust weather in the province is significant,dust weather occurred frequently during the period from 1971 to 1984,it was significantly decreased in past 20 years except that in 2002,and it occurs mainly in spring because of the influence of weather system,landforms and vegetation coverage,especially in April;(2) The impact of dust weather is most serious in the region northwest from Shenyang,Fuxin and northern part of Chaoyang;(3) The external and local sand source areas of dust weather in the province are the Horqin Sandland in east Inner Mongolia,northern part of north China,desertified lands in west Liaoning Province,northwestern part and partial central part of Liaoning Province.Strong wind and unstable atmospheric stratification in spring are the important factors resulting in the occurrence of dust weather in Liaoning Province;(4) Frequent occurrence of dust weather in Liaoning Province is mainly caused by the rapid temperature increase,strong wind,low vegetation coverage and low soil moisture content in spring;(5) Occurrence of dust weather in Liaoning Province has been effectively decreased because of building up the shelterbelts and implementing the weather modification.

Key words: dust weather, seasonal variation, impact degree, dust weather forecast, Liaoning Province