中文摘要：

利用1961~2007年青藏高原68个气象台站日照时数观测资料,通过统计方法分析了近47 a来青藏高原年日照时数的年代际变化趋势,得到以下几点初步认识：青藏高原年日照时数整体上呈现自东南向西北增加的特点,并且其空间变化趋势也存在明显的区域差异。青藏高原东南部、西藏中部和西藏西南部以及青海北部地区年日照时数减少较为明显,高原西部、西藏中东部地区和青海南部年日照时数呈增加趋势;近47 a来青藏高原年日照时数具有明显的年代际变化特征,年日照时数增加区和减少区分别存在12.1和21.1 a左右的时间尺度;增加区在20世纪60年代至80年代年日照时数处于偏多阶段,90年代至21世纪初日照时数呈明显的减少趋势;减少区则表现为20世纪60年代至70年代年日照时数有所增加,90年代日照时数开始急剧减少,21世纪初达到最低值。各年代之间年日照时数变化特点同样具有明显的区域差异。

英文摘要：

On the basis of the monthly sunshine duration data for the period 1961～2007 collected from 68 meteorological observation stations over Tibetan Plateau（TP） and by the methods of statistics analysis,the characteristics of interdecadal variation of the annual sunshine duration over TP were analyzed.The results of our research may lead to the following conclusions：The condition of annual sunshine duration over eastern and southern region of TP was in a poor state and the annual sunshine duration was abundant in western of TP.The variation trend of the annual sunshine duration over TP displayed a remarkable regional difference.The annual sunshine duration obviously decreased over southeastern,southwestern and central regions of TP and north of Qinghai Province,but obviously increased over western and central regions of TP and the southern of Qinghai Province.The interdecadal variation of the annual sunshine duration over TP is also remarkable.The annual sunshine duration increase region and decrease region appeared the remarkable period of 12.1a and 21.1a periodic oscillations,respectively.The annual sunshine duration of increase region raised from 1960s to 1980s then descended from 1990s to the beginning of the 21st century.The annual sunshine duration decrease region raised in 1960s and 1970s then descended in 1990s,and it reached to the bottom in the early 21st century.The spatial differences of annual sunshine duration over TP between each decade are also obvious.