陕西关中地区ET0计算公式的适用性评价

为明确参考作物蒸发蒸腾量(ET0)计算公式在陕西关中地区的适用性,该文按照FAO(1994)对Penman-Monteith公式的设定条件,采用称重式蒸渗仪测定ET0。以该实测值为标准,对具有代表性的ET0计算公式:FAO-17Modified-Penman(FAO-MP)、裴步祥修订的Modified Penman(PBX-MP)、Penman-Monteith(PM)、ASCEPenman-Monteith(ASCE-PM)公式进行对比分析,研究不同ET0计算公式在该地区的适用性及计算值产生偏差的原因。试验结果表明,ASCE-PM计算值与实测值最接近,线性回归系数为1.03(R2=0.87),绝对误差为0.31mm;其次为PM、PBX-MP、FAO-MP。气象因子对辐射项和空气动力项的不同影响造成各计算值与实测值的差异,其中,大气温度、日照时数及相对湿度对辐射项影响较大,风速对空气动力项影响较大。ASCE-PM公式可应用于陕西关中半湿润地区ET0计算。

Adaptability evaluation for reference evapotranspiration (ET0) formulas in Guanzhong Region of Shaanxi

To investigate the adaptability of ET0 in in Guanzhong Region of Shaanxi, four ET0 equations including FAO-17 Modified Penman (FAO-MP), China scholar Modified Penman (PBX-MP), Penman-Monteith (PM) and Standard ASCE Penman-Monteith equation (ASCE-PM), were assessed . on the basis of measured data by weighting Lysimeters. The results showed that ASCE-PM was the best equation for estimating ET0 in semi-humid area with a linear regression coefficient of 1.03 (R2=0.87) and mean absolute error (MAE) of 0.31 mm, compared to the measured values. The next was PM equation, followed by the PBX-MP and FAO-MP equations. The deviation between calculated and measured values was mainly caused by radiation and aerodynamic terms. Air temperature, sunshine and relative humidity had a significant effect on radiation term, while wind speed had a significant effect on aerodynamic term. The ASCE Penman-Monteith equation was proved to compute the local ET0 properly in Guanzhong region of Shaanxi province.