近50年甘肃日照时数时空变化特征及突变分析

利用甘肃省26个气象站1961—2010年逐月日照时数资料,采用线性趋势分析、异常年份分析、Mann-Kendall和功率谱等方法,分析了日照时数的时空变化及突变特征.结果表明:50年来,甘肃年日照时数表现为缓慢的下降趋势,气候倾向率为-0.29 h·(10 a)^-1,1997年以来显著减少;夏、冬季日照时数呈下降趋势,春、秋季则呈增加趋势;年日照时数异常偏少年份主要出现在20世纪80年代,而异常偏多的年份多发生在20世纪90年代至今;甘肃年日照时数空间差异明显,分布趋势基本上呈由东南向西北逐渐增多形势.Mann-Kendall和Yamamoto突变检验表明,四季日照时数未发生显著突变.周期分析表明,甘肃年日照时数存在2 a的振荡周期,通过了90%置信度检验.

Spatiotemporal variation and abrupt change analysis of sunshine duration in Gansu in the last 50 years

Monthly sunshine duration data collected in 26 weather stations in Gansu province from 1961 to 2010 were used to analyze the spatial and temporal variation and abrupt change of sunshine duration by using methods of climate tendency rate analysis,anomaly analysis,Mann-Kendall,spatial analysis,and power spectral analysis.The results showed that in the period from 1961 to 2010,the sunshine duration decreased very slowly with linear trend rate of -0.29 h/(10 a) but there was a pronounced and significant decrease phase from 1997 to 2010 with linear trend rate being -109.8 h/(10 a).Sunshine duration in summer and winter was on the decline,while it showed an increasing trend in spring and autumn.The annual sunshine duration was much less than normal in 1980s but extremely excessive since the 1990s.The results indicated that there were obvious spatial differences of the sunshine duration in Gansu province.The distribution trend of sunshine duration basically showed a gradually increasing situation from southeast to northwest.The results of Mann-Kendall and Yamamoto test indicated that there was no significant mutation for seasonal sunshine duration.Analysis of power spectrum showed that the sunshine duration of Gansu had quasi-periodic oscillation of 2-year and passed the 90% confidence level test.