关键词: 秋绵雨, 西南, 振荡周期

Abstract:

The climatic region of autumn continous rainy weather in Southwest China was divided by REOF analysis method with the daily precipitation data of 338 stations in the study area from September to November during 1961 to 2009. The trend of change, the abrupt change characteristic and periodic characteristic about autumn continous rainy days were analysed by linear trend, sliding t test, Yamamoto test, Mann-Kendall test and wavelets analysis method. The results show that there were more autumn continous rainy weather in the east than the west of Southwest China. In southeast of Sichuan, southwest of Chongqing and north of Guizhou, the autumn continous rainy weather were the most, with an annual frequency being above 80%, and the annual mean was above 10 days. There were four climatic zones about autumn continous rainy weather in Southwest China, including east of Sichuan Basin, west of Sichuan Basin, south of Guizhou and northeast of Yunnan. The autumn continous rainy days had a decreasing trend in the east of Sichuan Basin, south of Guizhou and west of Sichuan Basin. However, the northeast of Yunnan had an increasing trend, but all insignificant. The autumn continuous rainy days had an abrupt change from more to less in 1988 in south of Guizhou, it had an inverse mutation in 1985 and 1995 in northeast of Yunnan. The interdecadal oscillation period had obvious difference between each subregion, ranging from 10 a to 27 a. The interannual oscillation period was at a scale of 2-5 a in east of Sichuan Basin and south of Guizhou, but in west of Sichuan Basin and northeast of Yunnan, it was 2-3 a.

Key words: period of oscillation, autumn continous rainy days, Southwest China