Monthly calibration and optimization of ?ngstr?m-Prescott equation coefficients for comprehensive agricultural divisions in China

• 作者: XIA Xingsheng PAN Yaozhong ZHU Xiufang ZHANG Jinshui
• 来源期刊: 地理学报（英文版）
• 年，卷（期）: 2021,（7）
• 所属期刊栏目: Research Articles
• 页码范围: 997-1014
• 页数: 18页
• 语种: 英文
• DOI: 10.1007/s11442-021-1882-4

摘要

?ngstr?m-Prescott equation(AP)is the algorithm recommended by the Food and Agriculture Organization(FAO)of the United Nations for calculating the surface solar radia-tion(Rs)to support the estimation of crop evapotranspiration.Thus,the as and bs coefficients in the AP are vital.This study aims to obtain coefficients as and bs in the AP,which are opti-mized for China's comprehensive agricultural divisions.The average monthly solar radiation and relative sunshine duration data at 121 stations from 1957-2016 were collected.Using data from 1957 to 2010,we calculated the monthly as and bs coefficients for each subregion by least-squares regression.Then,taking the observation values of Rs from 2011 to 2016 as the true values,we estimated and compared the relative accuracy of Rs calculated using the regression values of coefficients as and bs and that calculated with the FAO recommended coefficients.The monthly coefficients,as and bs,of each subregion are significantly different,both temporally and spatially,from the FAO recommended coefficients.The relative error range(0-54％)of Rs calculated via the regression values of the as and bs coefficients is better than the relative error range(0-77％)of Rs calculated using the FAO suggested coefficients.The station-mean relative error was reduced by 1％to 6％.However,the regression values of the as and bs coefficients performed worse in certain months and agricultural subregions during verification.Therefore,we selected the as and bs coefficients with the minimum Rs estimation error as the final coefficients and constructed a coefficient recommendation table for 36 agricultural production and management subregions in China.These coefficient rec-ommendations enrich the case study of coefficient calibration for the AP in China and can improve the accuracy of calculating Rs and crop evapotranspiration based on existing data.