近50年中国天山日照时数变化及其影响因素

采用气候倾向率方法,对天山24个站1960-2009年逐月日照时数进行统计分析,并在ArcGIS环境下通过IDW插值法分析日照时数变化的空间分异。结果表明:近50年天山山区年日照时数表现为极显著的减少趋势,气候倾向率为-32.9 h/10 a,其中春季略有增加,冬季减少最为明显,夏、秋季均为缓慢的减少趋势。20世纪60年代天山年日照时数为正距平,仅春季日照偏少;70年代均为正距平,以秋季最为明显;80年代春、冬季日照充足,夏、秋季日照偏少,年日照时数为负距平;20世纪90年代和21世纪初年日照时数均为负距平,尤其以90年代的冬季最为明显;2000-2009年秋、冬季日照偏少,春、夏季日照偏多,日照时数有所增加。20世纪60年代年日照时数出现了异常偏多年份,90年代发生了异常偏少年份。年日照时数的变化与降水量和云量的多少有关。

Analysis on the Change of Sunshine Duration and Its Affecting Factors in the Tianshan Mountains in Recent 50 Years

In this paper, the annual and seasonal trend variation of sunshine duration in the Tianshan Mountains in China is analyzed using linear trend analysis based on the data of monthly sunshine duration, mean cloudage and precipitation from 24 meteorological stations in the mountains from 1960 to 2009. By using the method of IDW under ArcGIS, the spatial distribution of sunshine duration is analyzed so as to research the regional difference. The results show that the average annual sunshine duration in the Tianshan Mountains was significantly decreased in recent 50 years with a decreasing rate of 32.9 h/10 a. The change of seasonal sunshine duration was different, and the sunshine duration was decreased with a rate of-19.4 h/10 a in winter but increased with a rate of 0.7 h/10 a in spring. In addition, the sunshine duration in the 1960s was long in summer, autumn and winter, but short in spring. The positive anomaly of sunshine duration occurred in all seasons in the 1970s, especially in autumn. The sunshine duration was long in spring and winter but short in summer and autumn, and a negative anomaly of annual sunshine duration occurred in the 1980s. During the period from the 1990s to the beginning of the 21st century, the annual sunshine duration was short, especially in winter of the 1990s. Since the 21st, the sunshine duration was short in autumn and winter, but it was slightly increased in spring and summer. Moreover, more anomalous years of annual sunshine duration occurred in the 1960s, whereas less ones occurred in the 1990s. The results reveal that the change of sunshine duration is related to precipitation and cloudage.