北京地区潜在蒸散量计算方法的比较研究

利用北京地区1951—2007年的逐日气象资料,选取常用的7种公式计算日潜在蒸散量,并和利用FAO推荐的Penman-Monteith(PM)标准公式计算日潜在蒸散量进行比较。根据线性回归、平方根误差和平均偏差方法分析得出:Penman公式、Kimberly-Penman公式(KP)和Doorenbos-Pruitt公式(DP)与PM相关性较好,KP公式计算的ET0和标准ET0平均偏差和平方根误差均最小,可直接用来计算北京地区的ET0,而Penman公式和DP公式的平均偏差和平方根误差较大,不适合直接计算北京地区的ET0,利用气象数据提出了修正的Penman公式和DP公式。Makkink公式、Priestley-Taylor公式、Hargreaves公式和Turc公式与PM相关性较差,不适合计算北京地区的ET0。北京地区对ET0影响最大的气象因子为饱和水汽压差和净辐射,基于此,提出了2个适合估算北京地区缺资料条件下ET0的经验公式。

Comparison of Potential Evapotranspiration Methods in Beijing Area of China

In this paper,seven widely used and part-climatic-variables based ET0 methods are selected to calculate ET0,and compared with the FAO Penman-Monteith method using daily climatic data from 1951 to 2007 in Beijing area.Statistical methods of linear regression,root mean square error(RMSE) and mean bias error(MBE) are used to analysis ET0 difference between PM method and the seven methods.Results show that ET0s calculated using PM and KP methods are significantly linearly related and the values of RMSE and MBE are the least among the seven methods,therefore,KP method can be used to calculate ET0 in Beijing area directly.ET0s calculated using PM method and Penman and DP methods are also linearly related,while the values of RMSE and MBE are higher.We adjusted the Penman and DP methods using local climatic data and the modified ones can be used to calculate Beijing ET0.The Makkink,PT,Har and Turc methods are unsuitable for ET0 calculation in Beijing area because of the smaller determination coefficient between ET0s calculated using the four methods and PM methods.Vapor pressure deficit and net radiation are dominated factors influencing ET0 in Beijing area.Based on this result,we developed two experimental methods to calculate ET0 in Beijing area,which is very useful in areas with limited climatic data.