Abstract: Based on the surface gale data at 17 weather stations in Shijiazhuang region from 1972 to 2009, temporal and spatial distribution characteristics of gale days in the study area and 5 representative stations were analyzed by methods of a linear regression, a Morlet wavelet analysis and a Mann-Kendall mutation test. The results show that the spatial distribution of annual mean gale days is a “low-high-low” shape. The climatic characters of gale days are consistent in five representative stations with higher frequency in spring and lower frequency in autumn. The daily variation of gale frequency is significant. The gale frequency is higher in daytime than in nighttime.  The highest frequency occurs between 10:00 and 16:00 accounting for about 45.8%. The high frequent gale days appear in 1970s in Shijiazhuang region, so is in five representative stations. However, the number of gale days in these regions is in decreasing trends in the recent 38 years. There is a significant difference in average of gale days in the different regions during the same decade. The cycle characteristics of the annual gale days were significant in Shijiazhuang region and 5 representative stations, and the long and short cycles both appear during the few gale days. The annual gale day reduces mutationally in Shijiazhuang region and 4 representative stations.

Key words: Gale days, Temporal and spatial distribution, Cycle variation, Mutation test, Shijiazhuang