近47a华南前汛期旱涝特征

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

摘要:

采用华南61站47 a(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:47 a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2~4 a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47 a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。

Abstract:

Daily 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 pre-flood 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.