近47a华南前汛期旱涝特征

采用华南61站47a（1958-2004年）前汛期（4-6月）逐日降水资料，利用统计方法对华南前汛期的旱涝特征进行了研究。结果表明：47a来华南有12个涝年和12个旱年发生，较严重的旱涝年主要发生在20世纪50年代末至70年代中期以及90年代以后；前汛期旱涝变化以2～4a的年际尺度周期最为显著；4、5月旱涝的年代际变化特征较为一致，而5月与6月在年代际尺度上具有一定的反位相变化特征；地理分布上，可将华南地区前汛期降水分为5个旱涝异常气候区。近47a来桂南、粤西和东南沿海地区呈现旱—涝—旱的变化特征，而桂北区由旱转涝趋于雨涝的趋势明显，东北部山区由涝转旱趋于干旱的趋势明显。

Drought/Flood Characteristics of Pre-Flood Season in South China in Recent 47 Years

Dally precipitation of April,May and June during the period 1958-2004 from 61 observational stations is applied to study drought/flood characteristics of the pre-flood season in South China with statistic methods. Results show that 12 flood years and 12 drought years occurred in 1958-2004, with severe flood/drought years mainly in the late 1950s-the middle 1970s and after the 1990s; and the interannal period of 2-4 years was most remarkable in the flood/drought variations of the pre-flood season. The interdecadal character of the flood/drought variations for April and May was consistent, while the interdecadal variations for May and July showed an out of phase relation. South China can be geographically divided into five flood/drought anomaly sub-areas, and in the past 46 years, the preflood season climate showed an evolution trend of drought-flood-drought in southern Guangxi, western Guangdong, and the southeast coast region, a trend of drought-flood in northern Guangxi, and a trend of flood-drought in the northeast part of South China.