中文摘要：

利用新疆地区89个台站1961～2005年昼、夜降水观测数据，分析了该地区昼夜降水过程的时空演变特征，目的是认识这个地区在年降水增加背景下昼夜间降水过程的变化特征及趋势。研究结果表明：（1）1961～2005年，多年平均的降水量为夜大于昼，且昼、夜降水量均呈显著增加趋势；夜降水量增长趋势大于昼降水量，昼、夜年降水量增长趋势分别占年总降水增长趋势的49%、51%，这种变化在南、北疆存在明显的区域差异。昼、夜降水量都存在由少到多的显著突变，但两者发生突变时间不同，昼降水量发生突变的时间为1986年，而夜降水量的突变点却发生在1991年。（2）昼降水日数小于夜降水日数，且昼、夜降水日数都呈显著增加趋势，昼降水日数增加趋势大于夜降水日数。昼、夜降水强度都呈显著增大趋势，夜降水强度及其增长趋势均大于昼降水强度。降水量增加的主要原因是由于降水日数的增多，降水强度对降水量影响较小。（3）昼、夜毛毛雨日数都呈显著减少趋势，昼毛毛雨日数及其减少趋势均大于夜毛毛雨日数。而强降水的日数和强度均呈现增加趋势；昼、夜强降水量和各自的总降水量有很好的相关，强降水量对总降水量的影响很大。引起这些昼、夜间降水变化特征差异的原因有待于进一步研究。

英文摘要：

Observational day and night precipitation data from 89 stations in Xinjiang province during 1961–2005 were used to assess the temporal and spatial changes in daytime and nighttime precipitation processes. The goal of this investigation is to understand the change characteristics and trends of the precipitation process in both the daytime and nighttime in this area, under a background of increasing annual precipitation. The results show that the multi-year average of annual precipitation at nighttime was larger than at daytime during 1961–2005 and that precipitation increased significantly in both the day and the night. The increasing trend of precipitation is larger in the nighttime than in the daytime, with the annual increasing trend in the daytime and nighttime respectively accounting for 49% and 51% of the total increasing trend in annual precipitation. In addition, there are significant regional differences between southern and northern Xinjiang. The amounts of daytime and nighttime precipitation both show significant jumps, but at different times：In 1986 for the daytime, and in 1991 for nighttime precipitation. Further, the annual number of rainy days during the daytime is less than it is at nighttime, although they both show a clear increasing trend. This trend of increasing rainy days is greater for daytime precipitation than it is for the nighttime. Precipitation intensity in the daytime and nighttime also show a significant increase, with both precipitation intensity and the growth rate of precipitation intensity being greater at night than they are during the day. The increase in the number of rainy days is the main cause of the total increase in precipitation, while changes in precipitation intensity have little influence on the total. Meanwhile, the annual number of drizzle days show a distinct decrease in both the daytime and the nighttime. Drizzle days during the daytime are greater than at nighttime, and the decreasing rate is the same between day and night. Finally, the numbers of heavy pre