甘肃省近50a夏季极端强降水量的气候特征

利用甘肃省1960—2006年59个台站逐日降水资料，根据百分位值法定义了不同台站的极端强降水阈值，统计出了夏季（6～8月）逐年逐站极端强降水量，并进行了时空特征诊断。结果表明：一致性异常分布是甘肃省夏季极端强降水量的最主要空间模态；夏季极端强降水量的异常空间分布可分为陇南型、陇中型、河西西部型、河西东部型及陇东型5个关键区；在5个关键区中，陇南区、陇中区近47a来夏季极端强降水量表现出减少趋势，河西东部区与陇东区表现出增加趋势，而河西西部区却经历了少-多-少的抛物线型变化；另外从周期分析来看，甘肃省夏季极端强降水量近47a来在大多数分区存在11～13a和6～8a的振荡周期。

Climate Characteritic of Summer Extremely Heavy Precipitation over Gansu Province in Recent Half Century

Using daily precipitation data in 59 stations of Gansu province during 1960-2006,extremely heavy precipitation thresholds are determined for different stations,and the temporal and spatial distribution of summer extremely heavy precipitation is diagnosed in recent half century.The results show that the consistent anomaly distribution is main spatial mode for summer heavy precipitation in Gansu province,and the spatial mode is divided into five key areas: the Longnan area,the Longzhong area,the west of Hexi area,the east of Hexi and the Longdong area,respectively.The extremely heavy precipitation presented decreasing tendency in the Longnan and Longzhong areas,and increasing tendency in the east of Hexi and Longdong areas,but it came through few-more-few change in the west of Hexi area.From period analysis,the period vibration of 11-13 a and 6-8 a displayed clearly in most key areas.