青藏高原四季日照时数年际、年代际变化趋势分析

利用1961-2007年青藏高原日照时数资料，通过统计方法初步分析了近47年青藏高原四季日照时数的年际、年代际变化特征，得到以下几点初步认识：青藏高原四季日照时数整体上均呈现自东南向西北增加的特点，其空间变化也存在明显的区域差异：青藏高原西部和中部日照时数增加，高原东南部和北部呈减少的趋势。近47年来青藏高原四季日照时数年际和年代际变化明显，总体均呈减少趋势，20世纪60年代以偏少为主，70年代和80年代整体偏多，90年代和21世纪初高原日照时数以偏少为主，各年代之间日照时数区域差异明显。

Analysis on the Variation Trend of Interannual and Interdecadal Seasonal Sunshine Duration over Tibetan Plateau

On basis of the monthly sunshine duration data for the period 1961 -2007 collected from 68 observational stations over Tibetan Plateau (TP), the characteristics of interannual and interdecadal variation of the seasonal sunshine duration over TP are analyzed. The results of our research may lead to the following conclusions: The condition of seasonal sunshine duration over eastern and southern arid TP was in a bad state but good in western and northern arid TP, displaying a remarkable regional difference. The seasonal sunshine increased in western and middle TP and decreased in southeastern and northern TP. The seasonal sunshine duration over TP decreased remarkably in recent 47 years. The seasonal sunshine duration decreased in the 1960s and then increased in the 1970s and 1980s. In the 1990s and at the beginning of the 21st century, the seasonal sunshine duration decreased again. The spatial differences between each decade are also obvious.