川中丘陵区参考作物蒸发蒸腾量近60年变化成因研究

Attribution analyses of ET_0 change in hilly area of central Sichuan in recent 60 years

利用FAO-56Penman-Monteith方法计算川中丘陵区4个代表站点1954—2010共57年逐月的参考作物蒸发蒸腾量(ET0),分析ET0和各气象因子的变化趋势,采用贡献率分析法和偏相关系数分析法研究ET0近60年变化的成因。结果表明:ET0呈下降趋势;温度呈显著上升趋势;相对湿度呈显著下降趋势;日照时数和风速呈极显著减少趋势;川中丘陵区气候在近60年来趋向暖干化。日照时数和风速减少对ET0变化的负贡献率分别为-5.403%和-2.054%;相对湿度减少和温度增加对ET0变化的正贡献率分别为2.085%和0.562%;负贡献大于正贡献使ET0下降。因此,日照时数和风速减少是引起ET0近60年下降的主要原因。偏相关系数分析法得到的ET0变化成因与贡献率分析法得出的结论一致。

Reference crop evapotranspiration （ETo） from 1954 to 2010 was estimated with FAO-56 Pen- man-Monteith equation in four stations in hilly area of central Sichuan, China. The causes for ETo change were analyzed by using the contribution rate analysis method and partial correlation analysis method. The re- sults show that the trend of ETo declined; the temperature rose significant; relative humidity has a signifi- cant decrement; and sunshine duration and wind speed decrease very significantly. Climate tends to warm- ing and drying during the past 57 years. The negative contribution of decreased sunshine duration and wind speed to ETo trend is greater than the positive contribution of decreased relative humidity and increased tem- perature, inducing ETo to decline. Consequently, the change of ETo is primarily attributed to the significant- ly decreased sunshine duration and wind speed. In addition, the controlling meteorological variables affect- ing ETo change through partial correlation analysis is in accordance with the result by contribution analysis.