近50年来(1960—2007年)长江流域20cm口径蒸发皿蒸发量与太阳辐射变化的对比

Comparative analysis of variations of 20 cm pan evaporation and global solar radiation over the Yangtze River Basin during 1960—2007

利用长江流域147个气象站点1960—2007年的地面观测数据,通过计算,对比分析了长江流域20cm口径蒸发皿蒸发量与太阳辐射的变化关系.结果表明:长江流域近50年来蒸发皿蒸发量变化和太阳辐射变化呈显著正相关关系,二者均呈现显著下降趋势,蒸发皿蒸发量随太阳辐射的变化产生相应波动变化,而且中下游地区蒸发皿蒸发量变化受太阳辐射变化的影响程度更为明显;就季节变化而言,春夏秋冬4个季节长江流域蒸发皿蒸发量变化和太阳辐射变化同样呈现明显下降趋势,春、夏、秋3个季节二者变化关系高度相关,这三季对于流域全年蒸发皿蒸发量减少的贡献也最大;长江流域太阳辐射的显著下降是导致20cm口径蒸发皿蒸发量持续降低的主要原因之一.

Based on the ground-based observation data from 147 meteorological stations in nearly 50 years over the Yangtze River basin, applying climatology computational method for estimating global solm radiation, variation rela- tionship between global solar radiation and 20 cm pan evaporation was contrasted and analyzed from 1960 to 2007. The main results are as follows ： significant negative trend of global solar radiation and pan evaporation were detected in the upper, middle and lower reaches. Significant positive correlation existed between the global solar radiation and 20 cm pan evaporation, and the pan evaporation varies accordingly with the fluctuation of global solar radiation. The correlation coefficient between global solar radiation and pan evaporation in lower reach is higher than that in upper- middle reaches. In term of the seasonal variation, the research result indicates the same trend as the annual varia- tion, and the variation of both global solar radiation and pan evaporation showed significant negative trend in four seasons of the whole basin, especially in spring, summer and autumn, which contributes most to the decrease of pan evaporation in a year. Therefore, the significant negative trends in global solar radiation over the basin can be con- sidered one reason that causes the decrease in pan evaporation.