Abstract: The daily sunshine duration data in 1956?2005 from national meteorological information center are used to analyze the sunshine duration’s nonlinear trend behavior over China by the method of ensemble empirical mode decomposition (EEMD). The sunshine duration exhibits different nonlinear trends over different regions and in different seasons, most of them (over nearly 67.5% stations) show a descending trend, especially over the south and northeast China. The multi-decadal variability appears a climate shift in 1980s with the longer sunshine in the earlier stage and the shorter in the late part.

Key words: sunshine duration, EEMD, nonlinear trend, multi-decadal trend

摘要： 根据国家气象信息中心给出的逐日日照时数资料, 利用集合经验模态分解(ensemble empirical mode decomposition, EEMD)方法, 得到中国地区日照时数的非线性趋势变化特征。对各气象台站日照时数的非线性变化趋势类型做了分类以及分区域和季节研究, 并与线性趋势进行对比。结果表明: 近50年来中国地区绝大部分气象台站(占总气象台站数的67.5%)日照时数呈现下降的趋势, 尤其是在中国南部和东北地区, 呈现明显的区域特征和季节特征。日照时数的年代际变化整体上在1980年前后出现气候转型, 即呈现前期日照较长、后期较短的气候形态。

关键词: 日照时数, 集合经验模态分解(EEMD), 非线性趋势, 多年代趋势