Abstract: Based on the surface meteorological observation data from 9 stations in Tacheng region from 1961 to 2005, using the linear trend analysis, Mann-Kendall test, correlation analysis, and composite analysis, the temporal and spatial distributions and change characteristics of sand-dust weather were analyzed; and physical mechanisms for changes in sandstorms and blowing-sand weather were discussed. The results show as follows: 1) The high frequency area of sand-dust weather lies in the Wusu-Shawan area, the second high frequency area lies near Emin station. Distribution of day numbers of sand-dust (south-more-north-less) showed an opposite spatial pattern to both high wind days and precipitation(north-more-south-less). 2) The average annual sandstorm days over Tacheng region was 3.8 days, mainly in the period from April to September. 3) Sandstorm and blowing-sand days were decreasing in the period 1961-2005; sandstorm and high wind days obviously decreased at a rate of 1.0 d/10a and 10.5 d/10a, respectively. 4) An abrupt reduction in regional sandstorms, blowing-sand, and floating dust occurred in 1993, 1992, and 1973, respectively. 5) In the period 1961-2005, the northern hemispheric polar vortex showed a weakening trend in strength, and a shrinking trend in area, which was responsible for reduced intensity and frequency of the cold air activities in Xinjiang. Weakened cold air activities directly resulted in the reduction in annual mean strong winds, which was the primary reason for reduction in the day number of sandstorms.

Key words: Tacheng region, sand weather, spatial and temporal distribution, variation characteristic