中国地区日照时数近50年来的变化特征

Characteristic Analysis of Sunshine Duration Change in China during the Last 50 Years

根据国家气象信息中心给出的逐日日照时数资料,利用经验正交函数分解(EOF)和Mann-Kendall方法分析了1956～2005年中国地区日照时数的变化趋势、突变情况、时空分布和季节变化特征。研究表明:中国绝大部分地区近50年来日照时数总量呈减少的趋势,在1980年前后大部分观测站显示有突变,20世纪90年代之后减少趋势有所缓解,保持在稳定偏低的状态;此类变化趋势在东南地区较西北地区更为显著。且日照时数的上述变化主要由于夏季日照的变化造成的。

The sunshine duration daily data for 1956-2005, which was made available by the National Meteorological Information Center, is used to calculate sunshine duration trends, abrupt changes, temporal and spatial distribution, and seasonal variation through empirical orthogonal function （EOF） and Mann-Kendall analyses. The results show that： （1） Significant decreases in sunshine duration occurred over much of China during the latter half of the 20th century. The decreasing trend halted until the 1990s, after which time it was maintained at a low state. （2） Most of the meteorological stations happened abrupt climate change in 1980. （3） This change was significant, particularly in the eastern half of the country. （4） The change in summer sunshine duration is a major contributor to this decrease.