内蒙古近50年生长季日照时数变化特征

内蒙古生长季日照时数明显减少的趋势会对当地的农业生产有不利的影响.通过分析内蒙古自治区20个气象站1961-2010年生长季日照地面观测资料,用最小二乘法、累积距平、滑动t检验等方法分析了内蒙古地区近50年生长季的日照时数变化特征,揭示其主要的变化规律.结果表明:①内蒙古生长季近50年日照时数呈减少趋势,中部地区减少速率最大(-29.4 h/10a),西部地区其次(-19.10h/10a),东部地区最小(-14.7 h/10a).②内蒙古生长季日照时数在1978年附近存在一次显著突变,表现为日照时数的急剧减少；但其在减少的过程中有两次微弱的反弹.③生长季各月的日照时数变化趋势基本一致,呈现为不同速率的减少趋势.其中6月减少最多,其次是5、9、7、8月,4月减少最慢.

Variation Characteristics of Sunshine Duration in Growing Season over Inner Mongolia from 1961 to 2010

The downward trend of sunshine duration in growing season adversely affects agricultural production in Inner Mongolia. Through analyzing the sunshine duration data of 20 stations over Inner Mongolia from 1961 to 2010, using the methods of least square, cumulative anomaly, and moving t-test, the variation characteristics of sunshine duration in Inner Mongolia in the growing season in the 50 years are analyzed. The results show that： （1） The annual sunshine duration in growing season generally exhibited a decreasing tendency, and the decreasing rate in the central part was the most fast （-29.1 h/ 10a）, the next in the west （-19.10 h/10a）, and the least in the east （-14.Th/10a）. （2） There was a sudden change in 1978 and the decreasing tendency speeded up after 1978, but there were two slight increase periods in the process of reduction. （3） The monthly variation tendency of sunshine duration was different, which was the biggest in June, and the least in April.