西南地区秋绵雨变化趋势与周期性特征的区域差异

利用西南地区338 个气象站点1961-2009 年9-11 月的逐日降水资料，采用REOF对秋绵雨进行气候分区，运用线性趋势、滑动t 检验、Yamamoto 检验、Mann-Kendall 检验、复Morlet 小波等数学方法，分析各分区秋绵雨日数的变化趋势、突变特征、周期性特点，结果发现：西南地区秋绵雨东多西少，四川东南部、重庆西南部和贵州北部秋绵雨最多，年发生率在80%以上，年均日数在10 d 以上；西南地区秋绵雨可分为4 个气候区，即四川盆地东部区、黔南区、四川盆地西部区和滇东北区；其中四川盆地东部区、黔南区、四川盆地西部区秋绵雨日数有减少趋势，滇东北区有增加趋势，但均不显著；黔南区秋绵雨日数在1988 年发生了由多到少的突变，滇东北区秋绵雨日数则在1985 年和1995 年发生了两次相反的突变；各分区秋绵雨日数的年代际振荡周期差异较大，从10 a 到27 a 不等，年际振荡周期四川盆地东部区和黔南区为2～5 a尺度，四川盆地西部区和滇东北区为2～3 a尺度。

Area-differentiation of Changing Trend and Periodic Characteristics of Autumn Continous Rainy Days in Southwest China

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.