利用广东省23个台站1961-2006年后汛期(7-9月)逐候的降水资料,计算了降水集中度和集中期,并讨论了其时空分布特征和变化规律.结果表明,降水集中度和集中期能够表征降水量在时空场上的变化,降水集中度和集中期EOF的第1特征向量表现出一致的上升趋势,呈现东北—西南向分布,第2特征向量变化特征呈东西向反向分布.广东地区后汛期降水集中度呈逐年微弱下降趋势,并在年代际和年季尺度上存在不同的周期变化.广东地区降水集中度分布不均,在广东中部多水年的集中度大于少水年,多水年集中期要小于少水年.环流场的分析表明,集中度的高值年,1000 hPa、500 hPa上我国北方均易受高压控制,存在高度场的正距平中心,同时高压易于南伸,与南方暖湿空气交汇,容易导致强降水.%By use of the pentad precipitation data from 23 stations in Guangdong Province during the second rainy season (July to September) from 1961 to 2006, the characteristics of the spatial-temporal distribution and variation of precipitation are analyzed in terms of the Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP). The results show that PCD and PCP can reflect well the spatial-temporal distribution of the precipitation. There was a weak descending trend and various periodic variations at inter-annual and decade scales in PCD in Guangdong Province during the second rainy season. The spatial distribution of PCD shows the characteristic of decreasing from north to south successively. PCD had a uneven distribution, more concentrative over the central part of Guangdong in rainy years than dry years. PCPs in rainy years were smaller than those in dry years. By the empirical orthogonal function (EOF) method, the first eigenvector of PCD shows the characteristic of identical increasing trend over the province, with the contours being northeast-southwest oriented, but the second eigenvector is opposite from the east to the west. The circulation field analysis shows that in the high PCD years, the northern , -China was often controlled by high pressure systems at 1000 hPa and 500 hPa high fields, and there was usually a positive anomaly center in the height field, while the high pressure often extended southward, which converged with the warm and wet air, leading to strong precipitation.
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