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中文摘要：
采用宁夏18个气象站1960—2012年气象数据,基于SPEI在划分区域的基础上,研究了宁夏不同时空尺度的干湿状况的演变特征,干旱强度的变化趋势以及干旱影响范围的变化特征。结果表明：1近53a来宁夏地区存在明显的干湿变化,1998年之前是相对干旱的时期,干旱发生的频率高,强度大,影响范围广;1998年之后,宁夏大部分地区进入相对湿润时期,干旱发生的频率减少,强度也在下降,干旱影响的范围明显减小。2近53a宁夏存在湿润化趋势,北部的湿润化趋势要快于中部和南部。北部引黄灌区冬春季的湿润化趋势要快于夏秋季;而中部干旱带和南部山区则是秋冬季湿润化趋势要显著快于春夏季。3宁夏北部引黄灌区和中部干旱带的干旱强度有不同程度的减轻趋势,南部山区则有轻微的增强趋势,但不显著。北部引黄灌区各个季节发生干旱的总频次基本相当,但春旱的强度较大。中部干旱带的冬旱无论发生的总频次还是强度都高于其他季节;南部山区冬旱的发生频次最高,春旱的强度最大,达到了-2.22,属于极端干旱。4宁夏干旱发生的范围总体趋势是在减小,同时存在明显的阶段性特征。20世纪60年代前期、60年代后期到70年代中期、80年代中后期及90年代前期到中期的中度以上干旱发生的范围较大,2000年以后干旱发生的范围明显减小。
英文摘要：
Using meteorological data from 18 meteorological stations in Ningxia,the characteristics of dry and wet conditions in Ningxia were studied based on the SPEIindex,and the variation trends of drought intensity and the variation characteristics of drought affected area were studied.The results showed that：1there were obvious dry and wet changes in Ningxia area in recent 53 years,there was a relatively dry period in 1998,and the frequency of drought was high,the intensity was large,the influence was wide.After 1998,the frequency of drought occurred in most parts of Ningxia was reduced,and the intensity of drought was decreased.2In the past 53 years,there was a wetting trend in Ningxia,and the trend in the north was faster than that in the middle and south.Wetting trends of north of the Yellow River irrigation in the winter and spring were faster than those in summer and autumn,while in central arid zone and the southern mountain area,wetting trend were significantly faster in autumn and winter than that in spring and summer wet.3In the north of Ningxia irrigation area of Yellow River and central arid zone,drought intensity had a reducing trend,while southern mountain had a slight increasing trend,but not significant.The total seasonal drought frequency in the northern Yellow River irrigation area was basically the same,but the intensity of drought in spring was larger.In central arid zone,the total frequency and intensity of winter drought were higher than that of other seasons;and in southern mountain area winter drought had the highest frequency,the maximum drought intensity in spring reached-2.22,which was the extreme drought.4 The overall trend of drought incidence in Ningxia was decreasing,and there was obvious stage characteristic.In the early 1960＇s,the late 1960＇s to the mid 1970＇s,the middle of the 1980＇s to the later stage and the early 1990＇s to the middle stage of the twentieth century,the extent of the drought occurrence（medium degree or above）was larger,but after 2000,the extent of droug
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