1961-2009年东北地区日照时数变化特征

根据1961-2009年东北地区104个气象站的日照时数、气温、降水、风速和相对湿度资料，利用趋势分析、Mann-Kendall分析和相关分析等方法，研究东北地区日照时数月、季、年的时空变化特征，同时还对可能影响日照时数的气候因子进行分析。结果表明：东北地区5月日照时数最高，12月日照时数最低。年日照时数呈显著减少趋势，平均每10 a减少40.5 h；除秋季日照时数变化不显著外，其他季节日照时数均显著减少。在20世纪80年代初期存在明显的突变，日照时数开始减少。东北地区日照时数大致呈西高东低的经向分布；除黑龙江北部地区外，其余大部地区日照时数均呈减少的趋势，其中吉林北部地区减少最为明显。东北地区日照时数与气温呈负相关关系，相关系数为-0.40；与降水呈负相关关系，相关系数为-0.37；与风速呈正相关关系，相关系数为0.53；与相对湿度呈负相关关系，相关系数为-0.32。前三者均通过了99.9 %的信度检验，相对湿度通过了99.5 %的信度检验。

The characteristics of sunshine duration from 1961 to 2009 in northeast China

Based on the sunshine duration,temperature,precipitation,wind speed and relative humidity data at 104 weather stations from 1961 to 2009 in the northeast China,the monthly,seasonal and annual trends of the sunshine duration and its spatial distribution were analyzed using methods of a trend analysis,a Mann-Kendall test and a correlation analysis.The impacting factors of sunshine duration were also discussed.The results show that the highest and lowest sunshine duration occurs in May and December,respectively.The annual sunshine duration has a significant decreasing tendency with 40.5 hours per decade.The seasonal sunshine duration significantly decreases except for in autumn.The sunshine duration has an abrupt change in the early 1980s and then decreases.The sunshine duration in the northeast China is high in the west and low in the east.Except that in the northern Heilongjiang province,the sunshine duration in the other regions is in a decreasing tendency,especially in the northern Jilin province.The annual sunshine duration is in a negative correlation with annual mean temperature,precipiation and relative humidity,and the corresponding correlation coefficients are-0.40,-0.37 and-0.32 respecitvely,while it is in a positive correlation with wind speed and the correlation coefficient is 0.53.The relative humidity coefficient passes 99.5％ confidence levels,and the other passes 99.9％ confidence levels.