Monthly calibration and optimization of Ångstrom-Prescott equation coefficients for comprehensive agricultural divisions in China  

中国综合农业分区下的Ångström-Prescott公式系数逐月校正与优选

作　　者：XIA Xingsheng PAN Yaozhong ZHU Xiufang ZHANG Jinshui 夏兴生;潘耀忠;朱秀芳;张锦水(State Key Laboratory of Remote Sensing Science,Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences,Beijing 100875,China;Academy of Plateau Science and Sustainability,Qinghai Normal University,Xining 810016,China;Institute of Remote Sensing Science and Engineering,Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China)

机构地区：[1]State Key Laboratory of Remote Sensing Science,Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences,Beijing 100875,China [2]Academy of Plateau Science and Sustainability,Qinghai Normal University,Xining 810016,China [3]Institute of Remote Sensing Science and Engineering,Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China

出　　处：《Journal of Geographical Sciences》2021年第7期997-1014,共18页地理学报（英文版）

基　　金：National High Resolution Earth Observation System(the Civil Part)Technology Projects of China;Local Scientific&Technological Development Projects of Qinghai Guided by Central Government of China;Disaster Research Foundation of PICC P&C,No.2017D24-03。

摘　　要：Angstrom-Prescott equation(AP)is the algorithm recommended by the Food and Agriculture Organization(FAO)of the United Nations for calculating the surface solar radiation(R_(s))to support the estimation of crop evapotranspiration.Thus,the a_(s) and b_(s) coefficients in the AP are vital.This study aims to obtain coefficients a_(s) and b_(s) in the AP,which are optimized for Chinas 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 a_(s) and b_(s) coefficients for each subregion by least-squares regression.Then,taking the observation values of R_(s) from 2011 to 2016 as the true values,we estimated and compared the relative accuracy of R_(s) calculated using the regression values of coefficients a_(s) and b_(s) and that calculated with the FAO recommended coefficients.The monthly coefficients,a_(s) and b_(s),of each subregion are significantly different,both temporally and spatially,from the FAO recommended coefficients.The relative error range(0-54%)of R_(s) calculated via the regression values of the a_(s) and b_(s) coefficients is better than the relative error range(0-77%)of R_(s) calculated using the FAO suggested coefficients.The station-mean relative error was reduced by 1% to 6%.However,the regression values of the a_(s) and b_(s) coefficients performed worse in certain months and agricultural subregions during verification.Therefore,we selected the a_(s) and b_(s) coefficients with the minimum R_(s) estimation error as the final coefficients and constructed a coefficient recommendation table for 36 agricultural production and management subregions in China.These coefficient recommendations enrich the case study of coefficient calibration for the AP in China and can improve the accuracy of calculating R_(s) and crop evapotranspiration based on existing data.

关 键 词：solar radiation coefficient calibration Angstrom-Prescott equation least-squares regression agricultural divisions China 

分 类 号：S127[农业科学—农业基础科学]