中文摘要：

研究了1948～2003年全球陆地年降水量的长期变化. 研究表明,全球陆地降水量在近56年内平均减少为0.43mm/a.全球陆地降水量的第一经验正交函数（EOF-1）解释了97.9%的总方差,它的空间分布与全球年降水量的空间平均图非常相似,EOF-1的时间系数表现为明显的负趋势,趋势系数为-0.37,达到0.01的显著性,表明全球年降水量明显减少了.此外,研究了全球陆地季、月降水场变化的近期特征,计算了全球36个纬度带平均年降水量的长期趋势,指出有12个纬圈的年平均降水量趋势达到0.05的信度的显著性,其中只有1个纬度带（75°N～80°N）是正趋势.

英文摘要：

The investigation of secular variation of the global land annual precipitation（GLAP） for 1948 - 2003 suggests that GLAP experiences a decrease of 0.43 mm/a on average. The spatial distribution of the first empirical otthogonal function （EOF-1） for GLAP analysis accounts for 97.9% of the total variance, which shows almost the same pattern as that of the annual mean precipitation averaged for 1948 - 2003, with a similarity coefficient being as high as 0.99. The temporal coefficients of EOF-1 exhibit a remarkably decreasing trend with the trend coefficient being -0.37 and the confidence level being 99 %. Besides, the variations of seasonal and monthly precipitation over global land and their characteristics in recent years are analyzed, and the trend of GLAP for 36 latitude zones is also examined, h is concluded that the trend coefficients of 12 latitude zones are significant at a confidence level of 95 % , while only one latitude zone（75°N- 80°N） out of 12 zones shows a positive trend.