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Penm an-Monte ith公式中as和bs是计算净辐射不可缺少的参数,采用江苏射阳2002年日气象资料,分别采用FAO56推荐值和邻近地区南京市的校正值进行计算,得到了日参考作物蒸发蒸腾量和相应的太阳辐射与净辐射资料。分全年、夏半年和冬半年等不同情况分析了2种取值方案计算结果的差异。结果表明:采用邻近站点推荐值计算得到的参考作物蒸发蒸腾量ET0和净辐射Rn计算结果与FAO推荐值计算结果相比偏大,并且在计算值较小的冬半年误差也相对较大。与此相反,采用邻近站点推荐值计算得到太阳辐射Rs的计算结果偏小,并且在计算值较大的夏半年误差更大。因此,参数as和bs的选择对于参考作物蒸发蒸腾量计算结果的影响是不可以忽略的,尤其在辐射较低、蒸腾较弱的冬半年,根据实测的辐射资料进行校正是很有意义的。
As and bs in Penm an-Monteith formula are indispensable parameters for calculating net radiation. Based on the daily meteorological data of Sheyang of Jiangsu in 2002, the values of FAO56 and the corrections of Nanjing of neighboring areas were used respectively to calculate the daily reference crops Evapotranspiration and corresponding solar radiation and net radiation data. The results of two kinds of schemes are analyzed in different situations such as whole year, summer half year and winter half year. The results show that the calculation results of reference crop evapotranspiration ET0 and net radiation Rn calculated using the recommended values of neighboring stations are larger than those calculated by the FAO recommendation, and the errors are relatively large in the winter half of the small calculation. On the contrary, the calculation results of solar radiation Rs calculated using the recommended values of neighboring stations are small, and the errors are larger in the summer half of the year when the calculated value is larger. Therefore, the choice of parameters as and bs is not negligible for the calculation of reference crop evapotranspiration. Especially in the low temperature and low transpiration, in the winter half year, it is very meaningful to calibrate according to the measured radiation data.