Analysis on the Precipitation Characteristics in the Rainy Season in Liupanshui City in Recent 50 Years

[Objective] The research aimed to study the variation rule of precipitation in the rainy season in Liupanshui City in recent 50 years. [Method] Based on the monthly precipitation data from three observatories (Liuzhi, Panxian and Shuicheng) of Liupanshui City from May to September during 1960-2009, the interannual, interdecadal variation and mutation characteristics of precipitation in the rainy season in Liupanshui City in recent 50 years were analyzed by using the linear tendency estimation, sliding T-test and Morlet wavelet analysis method. [Result] The rainfall in the rainy season in Liupanshui City in recent 50 years presented the decline trend, and the linear tendency rate was -15.4 mm/10 a. The precipitation in the rainy season in Liupanshui City had the obvious interannual and interdecadal variation characteristics. It was the obvious rainless period in the metaphase of 1960s, and the precipitation was comparatively more in late 1960s. It was the relatively rainless period in the whole 1970s. From late 1970s to late 1980s, the precipitation in the rainy season entered into the pluvial period, and it was the period when the precipitation was the most in recent 50 years. The precipitation was relatively less from late 1980s to metaphase of 1990s. It was the pluvial period in the middle and late periods of 1990s, and it was the rainless period when entered into the 21st century. The sliding T-test showed that the precipitation mutation point in the rainy season in Liupanshui City in recent 50 years was in 2002. The wavelet analysis showed that the precipitation in the rainy season in Liupanshui City had the significant multiple time scale characteristic. In the interdecadal scale, the precipitation had the significant 16-year periodic oscillation which stably existed in 50 years. In the interannual scale, the precipitation had the quasi-8-year periodic oscillation. [Conclusion] The research provided the scientific basis for the accurate forecast of drought and flood disasters, disaster prevention and reduction in the city.

THE IMPACT OF PRECEDING ATMOSPHERIC CIRCULATION AND SST VARIATION ON FLOOD SEASON RAINFALL IN YUNNAN

Spatial and temporal distribution characteristics and scale range of two significant areas were obtained by analyzing the relationship among summer rainfall in Yunnan province, height field and SST field (40°S – 40°N, 30 °E – 70°W) across the North Hemisphere at 200 hPa, 500 hPa and 850 hPa for Jan. to May and correlation, and field wave structure. Remote key regions among summer rainfall in Yunnan province, height field and SST field (40°S – 40°N, 30°E – 70°W) across the North Hemisphere at 200 hPa, 500 hPa and 850 hPa were studied through further analyzing of the circulation system and its climate / weather significance. The result shows that the forecast has dependable physical basis when height and SST fields were viewed as predictors and physical models of impacts on rainy season precipitation in Yunnan are preliminarily concluded.