中文摘要：

应用黑龙江省2个气象台的逐日气象资料,引入自由搜索（Free Search）算法求解模型参数,建立了日、旬、月3种时间步长的Hargreaves公式改进式,并对这些改进式的适用性进行了评价。结果表明,以Penman-Monteith公式计算的ET0为评价标准,Hargreaves公式改进式与FAO推荐的Hargreaves公式修正式的计算精度相当,且Hargreaves公式改进式解决了标准Hargreaves公式计算值为负数的问题,为发展Hargreaves公式提供了一种简便方法。

英文摘要：

To improve the application of Hargreaves equation,Free Search was employed to get the parameters of modifying Hargreaves equations based on daily meteorological data of Jiansanjiang and Harbin in Heilongjiang province,and the evaluation of the modified Hargreaves equations were verified by three time steps of daily,ten-day and monthly.The results show that the modified Hargreaves equations can solve the problem of the negative ET0,and its accuracy is identical with the verified Hargreaves equations recommended by FAO,when ET00 values calculated from Penman-Monteith equation is taken as standard.And what＇s more,a simple method for developing Hargreaves equation was developed.