中文摘要：

华北平原地处东亚大陆性季风气候区，是世界上气候极脆弱的区域之一，干旱灾害频发。依据多年平均降雨等值线将华北平原划分为3个子区域（A区雨量〈600mm，600mm≤B区雨量≤750mm，C区雨量〉750mm），基于1960-2009年60个站的逐日气象资料，采用修正的Palmer干旱指数（PDSI）、M-K检测法和EOF分析法研究了该地区近50年气象干旱的时空变化特征。结果表明，PDSI指数能较好地表征华北平原气象干旱的时空变化过程，其干旱的空间分布主要呈南-北和东南-西北递增的格局，干旱过程通常持续两年以上，季节连旱现象明显，年际变化和年代际变化十分显著。A区干旱最为严重且呈显著增长趋势，其突变点大致为1983年；B区自1970年后进入干旱频发期，持续时间达20年之久；C区各级干旱频率均呈下降趋势，大致以1997年前后为突变点。

英文摘要：

North China Plain （NCP）, one of most vulnerable climatic region in the world, located in the mainland monsoon circulation of Eastern Asian, severely and repeatedly suffers from drought hazards. In this paper, accord- ing to daily meteorological data of 60 stations from 1960 to 2009, and based on the modified Palmer drought severity index （PDSI）, the M-K detecting method and the EOF analysis method, the spatial and temporal variations charac- teristics of meteorological drought of NCP was studies. The NCP was divided into three sub-regions （A, B and C, respectively） according to the rainfall contours of 600 mm and 750 mm. It is found that droughts happening in NCP could he characterized well by the PDSI index, and usually last for more than two years, not only going through one season after another, but also with significant inter-annual and inter-decadal variations. Moreover, there are two leading patterns of the spatial distributions： severity and duration of drought always increase from south and south- east to north and northwest. Droughts in district A are the most serious, and increase significantly with an abrupt change at about 1983, while droughts in district B also have a remarkable increase since 1970s which last for a two- decade dry spell. However, the drought frequencies of C-subregion drop down gradually during last 50 years withthe year of 1997 of abrupt change point.