近51年海河流域作物生长季干旱时空分布特征研究

基于1960-2010年海河流域及周边地区116个气象站逐月气温和降水资料，采用相对湿润度指数M作为干旱评价指标，分析海河流域作物生长季（春季至秋季）气象干旱发生的时空分布特征．结果表明：（1）春季海河流域干旱最为严重，多年平均干旱率高达56．90％；夏季较春季干旱率明显降低，多年平均干旱率为7．59％；秋季干旱率呈现出增加趋势．（2）春季干旱在1960年代最为严重，夏季干旱在1990年代最为严重，而秋季干旱在1980年代最为严重．（3）春季干旱发生概率最高，整个海河流域均在19．61％以上，干旱发生概率在50％VA上的地区面积占海河流域的3／4，河北东北部和京津一带是春季干旱发生概率最高的地区；夏季干旱发生概率较春秋低，干旱发生概率最高的地区为大同和张家口以北地区；大部分地区的秋季干旱发生概率在25％以上，发生概率最高的区域主要集中在京津唐地区．

Spatial and temporal distributions characteristics of drought during crop growth period in Haihe river basin over past 51 years

Based on the data of monthly mean surface air temperature and monthly precipitation from 116 meteorological stations in Haihe river basin and the around area during 1960-2010, the drought index in crop growth period （from spring to autumn） from 1960 to 2010 are calculated using the relative humidity index（M）, and then the spatial and temporal distribution characteristics of meteorological droughts are analyzed. The results are as follows ： （ 1 ）Spring drought was the most serious event and the 51-year average drought rate in spring was 56.90%. Drought rate in summer was lower than that in spring and the 51-year average drought rate in summer was 7.59%. In autumn, drought rate presented an upward trend. （2）Over the past 51 years in Haihe river basin, spring drought in the 1960s was the most severe one. The most serious in- terdecadal droughts occurred respectively in summer in the 1990s, autumn in the 1980s. （3）Occurrence probability of spring drought was more than 19.61% in the whole river basin and the areas with drought occurrence probability more than 50% accounted for 3/4 of the whole study area. The highest occurrence probabilities of spring drought were almost distrib- uted in the northeast of Hebei province and the Beijing-Tianjin area. Occurrence probability of drought in summer was lower than than in spring. In summer, the highest drought-prone areas were mainly located in the north of Datong and Zhangjiakou. Occurrence probability of autumn drought was more than 25% in most area of the whole river basin. The highest drought-prone areas in autumn were mainly located in Beijing-Tianjin-Tangshan area.