The wavelet analysis of summer precipitation characteristics in Xilinhot from 1961 to 2010

Using the wavelet analysis method with Mexican Hat Function, the characteristics of summer precipitation in Xilinhot from 1961 to 2010 was analyzed. The results showed that the cycle of summer precipitation varied with timescales which supported by weak oscillation with larger timescale and volatile oscillation with smaller timescale. The first, second, third and fourth main period of summer precipitation periodic oscillation was 30, 27, 24 and 21 years, respectively. The summer precipitation and periodic changes had an impact on annual precipitation. For the summer precipitation, the cycle was 7 to 15 year for the timescale with more than 30 years, the cycle was 10 years for a 15 year timescale and the cycle was 2 to 9 years for a 9 year timescale. For the timescale with less than 3 years, the periodic oscillation significantly strengthened, the cycle was shorter and unstable, and the precipitation was obviously uncertain. The precipitation was the key factor to determine the grassland vegetation growth status and nutrient accumulation and content.