1971 ~ 2012 年南阳市日照时数的变化特征简

利用南阳市气象站1971～2012年的日照资料，采用线性倾向估计、Morlet小波分析、M-K检验等方法，研究了42年来南阳市日照时数变化情况。结果表明，近42年来南阳市20世纪70、90年代平均日照时数高于42年年平均值；80年代、2000年以后平均日照时数低于42年年平均值。南阳市年日照时数呈减少趋势，夏、秋、冬季日照时数也呈减少趋势，春季日照时数呈微弱的增长趋势；日照月变化趋势为1～4月逐渐增多，5月达全年最高值，9～12月一直为下降趋势；从气候变化趋势来看，1、2、5～12月月日照时数呈减少趋势，3、4月月日照时数呈增加趋势；近42年南阳年日照时数变化存在3个明显的周期震荡，分别是6～8、26～28和35～36年的尺度：自1971年以来，南阳市年平均日照时数一直处于下降趋势，根据UF和UB曲线交点的位置，确定南阳市年日照时数21世纪的减少趋势是一突变现象，具体是从2001年开始。

Variation Characteristics of Sunshine Hours in Nanyang City during 1971 -2012

Using sunshine data in Nanyang Meteorological Station during 1971 -2012, adopting linear trend estimation, Morlet wavelet analy- sis and M-K test, the variation situation of sunshine hours in Nanyang City in recent 42 years was studied. The results showed that the average sunshine hours in 1970s＇and 1990s＇is higher than 42 years annual mean, the average sunshine hours in 1980s＇and after 2000 is lower than the annual mean. The sunshine hours in summer, autumn and winter showed decreasing trend, while spring indicated slight increasing trend; the monthly variation trend of sunshine is increasing during Jan. to Apr. , up the highest value in May, and decreasing during Sep. to Dec.. See- ing from the climate variation trend, the monthly sunshine hours showed decreasing trend in Jan. , Feb. May to Dec. , and increasing in Mar. and Apr.. The annual sunshine duration change in Nanyang has 3 obvious periodic oscillation, they are 6 - 8 a, 26 - 28 a and 35 - 36 a scale. Since 1971, the average annual sunshine hours in Nanyang City have been in a downward trend. According to UF and UB curve inter- section point position, the decreasing trend of annual sunshine hours in Nanyang City in 21st Century is a sudden phenomenon, specifically from the beginning of 2001.