Based on the daily precipitation data collected from 50 meteorological stations in South China, the temporal and spatial variations and abnormal distributions of extreme precipitation events defined by the modified percentile method in the early rainy season(ERS)and the late rainy season(LRS)of South China from 1961 to 2014 were analyzed and possible reasons of differences were discussed by using more-let wavelet analysis and SVD method.The results indicate that the extreme precipitation indexes of ERS and LRS during recent 54 years have a significant interannual variation with 3-5 years and 6-8 years periods,respectively,and showing a trend of slight increase.The distributions of extreme precipitation index are also significantly different between ERS and LRS.The maximum anomalies of ERS are mainly in the northeast Guangxi and central part of Guangdong,but those of LRS are near the coastal areas.The possible reasons for the differences between ERS and LRS are as follows:①The atmospheric circulation and SST anomalies in the preceding winter can be considered as important factors of the extreme precipi -tation events in ERS of South China.Due to the onset of summer monsoon,the strong southwesterlies car-rying warm and wet air from the South China Sea merge with the north cold air at the north-central region of south China,and convection becomes stronger, which is more prone to heavy precipitation.The in-crease of SST in tropical Pacific,especially over the central eastern Pacific,creates a favorable condition for extreme precipitation in ERS.②The extreme precipitation in LRS shows no obvious relationship with atmospheric circulation features.The warmer local SST and stronger convection are helpful for tropical cy-clones to move westward,which increases extreme precipitation in the coastal areas of South China.%根据1961-2014年华南地区50个测站的逐日降水量资料,采用改良后的百分位法定义了华南地区前后汛期的极端降水,并运用小波分析、SVD等统计方法分析了华南地区的前、后汛期极端降水事件的时空变化规律以及可能影响原因.结果表明:近54 a来,华南地区前、后汛期极端降水都有明显的年际变化,极端降水指数都呈上升趋势,但是变化周期不同,分别具有3~5a和6~8a的显著的变化周期;华南地区前、后汛期的极端降水指数的空间分布存在差异,前汛期在广西东北部和广东中部极端降水指数较大,后汛期在华南沿海地区极端降水指数较大.造成前、后汛期上述差异的可能因素是:①大气环流和前冬海温异常变化可能是影响华南前汛期极端降水的重要因素.前汛期由于南海夏季风的爆发,强盛的西南气流由南向北输送暖湿气流,同时北方冷空气延伸至华南地区,冷暖空气在华南中北部交汇,对流旺盛,易于发生极端降水;前汛期前冬季赤道太平洋海温异常增暖特别是中东太平洋的增暖,为华南地区前汛期降水偏多创造了有利条件;② 后汛期极端降水的主要原因是局地海温增加,对流旺盛,西北太平洋和南海热带气旋的增多,在华南沿海地区易出现极端降水.
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