中文摘要：

基于WRF模式,采用1980年和2000年的土地利用/覆盖数据分别进行了连续21年的模拟试验（EXP1980和EXP2000）,进而分析了中国东部LUCC对夏季降水影响的不稳定性及其与大尺度气候背景的关系。结果发现：（1）中国东部以农—林（草）转换为主要特征的LUCC对夏季降水的影响因年份而异,在1981年、1984年、1986年、1988年、1989年和1996年（LR年）,EXP1980比EXP2000中国东部降水偏多,在1992年、1993年、1994年、1995年、1997年和1999年（MR年）,EXP2000比EXP1980中国东部降水偏多;（2）LR年与MR年的气候背景显著不同,MR年相比LR年位势高度场呈“西高东低”,降水场呈“南多北少”的格局,并且该特征得到了NCEP2再分析数据的印证。这意味着20世纪80-90年代南方降水增加可能部分由LUCC所致,北方降水减少则因LUCC而弱化。

英文摘要：

Precipitation could be impacted significantly by Land Use/Cover Change （LUCC）. However, the variability of impacts of LUCC on precipitation and its dependences on the large- scale climate background have been little studied. In this study, numerical experiments with the Weather Research and Forecasting （WRF） model for 21-year （1980-2000） were carried out. There were two experiments with exactly the same settings except for the underlying land use/ cover. One experiment used land use/cover for the early 1980s （hereafter called EXP1980） and the other one used land use/cover for the 2000 （hereafter called EXP2000）. Through comparing the two experiments with each other, the inter-annual variability of impacts of LUCC on summer precipitation over eastern China and its dependences on the large-scale climate background were disclosed. The results show that the LUCC exerted varied impacts on the summer precipitation along with the inter-annual variations of climate background. On the climate background of 1981, 1984, 1986, 1989, and 1996 （hereafter called LR years）, the LUCC from the early 1980s to 2000 may lead to a decrease of precipitation over eastern China, in particularly in the southwest and northeast of China. On the climate background of 1992, 1993, 1994, 1995, 1997, and 1999 （hereafter called MR years）, the LUCC may lead to an increase of precipitation over eastern China, particularly in Southwest and Northeast China. Between the LR years and MR years, climate backgrounds have significant differences. There was a higher geopotential height in the west and a lower geopotential height in the east in the MR years than those in the LR years. Thereby, there was an anomaly of high pressure over Mongolia and an anomaly of low pressure over the Sea of Okhotsk. As a consequence, there was more precipitation in the south and less precipitation in the north in MR years than those in LR years. Such differences of climate backgrounds between MR years and LR years simulated by WRF model were also