河北省干旱分布特征和变化规律分析

选取河北省有连续观测资料的72个观测站日降水量和日平均气温，利用干旱综合指数方法计算1970-2009年的每日干旱综合指数。应用干旱综合指数（C_i）对河北省干旱过程进行监测与诊断，分析河北省气候干旱的时空变化特征及其成因。结果表明：河北省各地都有干旱发生，中南部为干旱多发区；各地区均是4月和5月干旱发生频率最高，秋季干旱发生的频率也很高；过去40 a中，河北省年干旱日数、生长季干旱日数总体上没有显著增加或减少；从四季来看，春季干旱日数存在明显的减少趋势，夏、秋季有增加的趋势，冬季的变化趋势相对较小。 

Analysis on Distribution and Variation of Drought in Hebei Province

In this paper,the daily drought indexes in Hebei Province during the period of 1970-2009 were calculated using the compound drought index(Ci) based on the daily precipitation and air temperature data from 72 meteorological stations in the province.Ci was used to monitor and recognize the drought processes occurred in Hebei Province,and the spatiotemporal variation of climate drought was analyzed.The results are as follows:(1) Drought occurred everywhere in Hebei Province in recent 40 years,especially in the central-southern part;(2) Drought frequency was the highest in April and May in all the regions of the province,and autumn drought also occurred frequently;(3) In the mass,there was no obvious increasing or decreasing trend of both annual and seasonal drought days in recent 40 years;(4) Seasonally,drought days were in an obvious decrease trend in spring,an increase trend in summer and autumn,and a slight variation in winter.