河南省汛期极端降水事件分析

利用河南1961～2006年50个气象站台站汛期（6～8月份）逐日降水量资料，定义95%降水分位数为极端降水事件的阈值，建立不同站近46年汛期极端降水事件发生频次的时间序列。在此基础上采用趋势分析、最大熵谱分析等统计技术方法，对河南降水事件发生频次的空间分布及年际变化特点进行了分析。结果表明：空间变化上总体具有北多南少的特点，而且汛期降水量的比重与极端降水事件发生频次的高低存在着很好的一致性；空间分布上主要有全省一致型、西北 东南型、南阳盆地型和中部分布型等4种类型，其中全省一致分布型为最主要的空间模态；年际变化趋势各地有所不同，豫西、豫南区为减少趋势，而豫中、豫北、豫东和豫西南区表现为增加趋势，而且在振荡形态上各有同异，以2~8年和10年左右的年代际变化最为普遍。

ANALYSIS ON EXTREME PRECIPITATION EVENTS IN FLOOD SEASON OF HENAN PROVINCE

Based on the daily rainfall data of meteorological stations of Henan Province in the flood seasons (1961~2006)，taking 95 percentiles as threshold value of precipitation events，the time series of frequency of extreme precipitation events in the past forty six years was constructed，the methods of trend analysis，maximum entropy spectrum analysis and other statistical techniques were employed to analyze the characteristics of spatial distribution and inter annual variation.The results showed that：totally，the frequency of extreme precipitation events in south area was higher than that of in north area in Henan，and there was a consistency between the proportion of rainfall in flood seasons and the frequency of extreme precipitation events；There were four different patterns of spatial distribution：the type of consistency in provincial range，the type of northwest to southeast，the type of Nanyang Basin and the type of midland；The change tendency was different in different areas in the past forty six years，the extreme precipitation events tended to be decreasing in the west area and south area，yet there was a increasing trend in north area，east area，middle area and south west area；and the inter decadal change characteristics of frequency oscillation was different respectively，and the cycle of two to eight years and the cycle of ten years were the most common.