中文摘要：

基于高分辨率CRU数据集1950-2009年的逐月资料,计算湿润指数,采用回归分析和偏相关方法分析中国区域干湿变化特征及原因.结果表明,1950-2009年中国总体呈现明显的干旱化趋势,以秋季最为显著;中国降水量呈现微弱的增加趋势（0.04 mm/10 a）,潜在蒸发量呈现显著增加趋势（0.71 mm/10 a）,潜在蒸发量的显著增加促进了中国干旱化.湿润指数变化的空间分布在东部和西部地区呈相反的趋势,降水量减少而潜在蒸发量增加的共同作用成为东部地区干旱化的直接原因;降水量增加而潜在蒸发量减少（微弱增加）为西部地区干旱适度缓解的直接原因.太阳短波辐射对潜在蒸发量的影响最大,其次为平均温度、水汽压、温度日较差、云量和降水量.

英文摘要：

With data on monthly precipitation and potential evaporation of climatic research unit during 1950-2009,the surface humid index was calculated to analyze regional distribution and time variation of the changes in dryness and wetness,and to explore the main effects of different regional dry- wet changes.The results showed that to become drought was the main trend in China during 1950-2009.Drought was the most significant in autumn.Precipitation showed an unobvious increase（0.04 mm/10 a）,and potential evaporation showed a significant increase（0.71 mm/10 a）,which was the main reason behind the drought that happened in China.The China drought index in the western and eastern regions showed the opposite trend.Increasing precipitation and decreasing（or weak increase） potential evaporation were direct reasons for the western wetness.The reason for the eastern aridity was also opposite to the western situation,with downward solar radiation effect on the potential evaporation being maximum,and the partial correlation coefficient reaching 0.80,followed by temperature,water vapor pressure,daily range of temperature,and cloud cover.The significant climate tendency of solar radiation and temperature were closely related to the significantly increasing potential evaporation.