Abstract: Based on the observational data from 110 weather stations from 1971 to 2009 in He’nan province, the spatial-temporal distributions of gale days and the relationship between gale days and sand-dust days were analyzed. The results show that the annual mean gale days decrease significantly with the rate of 2.2 d/decade in recent 39 years, so are the seasonal mean gale days and the rates are 0.8 d/decade in spring, 0.6 d/decade a in winter, 0.4 d/decade in autumn and 0.3 d/decade in summer. For the annual scale and seasonal scale, the inter-decadal gale days decrease in He’nan province. The gale weather mainly occurs in spring and winter, and the number of gale days in these two seasons can account for 40.8% of that for the whole year. For the monthly gale days, the maximum occurs in April and the minimum appears in September, and their percentages are 15.5% and 1.9%, respectively. The spatial distributions of annual mean gale days are related to the topography in He’nan province. The gale weather often occurs in the southeast of Taihang Mountains and the middle-northern regions of Henan province where the elevation changes from lower to higher. Whereas it seldom occurs in the eastern regions where the topography is flat and the western regions where there are a lot of mountains and the elevation is relatively high. The annual mean blowing sand days and sand-dust storm days decrease significantly with the rates of 0.4 d/dec and 0.3 d/dec from 1971 to 2009, and both are in significantly positive correlations with gale days based on Pearson’s correlation analysis and the correlation coefficients are 0.88 and 0.75 respectively. The annual variations of gale days could influence the sand-dust weather, and the decrease of gale days is the main reasons causing the decrease of sand-dust weather in He’nan province.

Key words: Gale days, Spatial-temporal distribution, Dust weather, He’nan province