【摘要】 对１９９９年中国夏季降水特征及其成因的分析表明，１９９９年夏季中国长江中下游地区降水偏多有其重要的气候背景，主要受到降水年代际振荡湿期的影响，而 Ｌａ Ｎｉｎａ事件的冬季增强是造成 １９９９年中国夏季雨带位置偏南，北方少雨干旱的重要物理因素。更多还原

【Abstract】 The distribution of precipitation and its cause during the summer of 1999 have been inves- tigated. The results show that it is the decadal-to-interdecadal oscillations of precipitation in the mid- dle and low reaches of the Yangtze River, which is in the wet phase from the recent decadal, that is considered as the most important climate background of the relative richer rainfall during the summer of 1999. Furthermore, the intensifying of La Nina event in the former winter is accounted for the south- ward excursion of main rain belt and drought in the north of China.更多还原