地表太阳辐射经验值对参考作物需水量计算的影响

Influence of Solar Radiation Empirical Values on Reference Crop Evapotranspiration Calculation in Different Regions of China

针对中国太阳辐射站点观测数据较少的客观条件,以联合国粮农组织(FAO)建议的通过Angstrom公式及其参数计算的地表太阳辐射(Rs-c)对中国九大农业区基于Penman-Monteith(PM)公式计算的参考作物需水量(ET0-PM)的影响为目标,利用中国地面气候资料月值数据集和中国辐射月值数据集中的112个站点1957年1月—2017年3月的气象要素逐月有效观测日均值数据,通过对比分析和相关分析,讨论了站点Rs-c与观测的地表太阳辐射(Rs-o)的时空差异,以及二者分别输入PM公式获得的ET0-c和ET0-o的时空差异。结果表明:基于年内时空尺度的各农业区Rs-c和Rs-o存在显著且不稳定的差异,Rs-c直接替代Rs-o参与计算ET0-c可能出现较大的误差。基于Rs-c和Rs-o分别计算的ET0-c和ET0-o,无论是在全国,还是各个农业区,均存在显著的线性相关性,R2超过0.67,ET0-c平均值只有0.06~0.26 mm/d的误差。考虑中国的农业地域类型,应对北方地区的“春旱”灌溉需求,可以直接以Rs-c计算获得ET0-c,而在全国范围内的夏季“伏旱”期,输入Rs-c计算的ET0-c比输入Rs-o计算的ET0-o偏大。在高精度的节水农业应用中,建议研究相应的校正模型对夏季ET0-c进行校准。

Solar radiation(Rs)is a necessary input variable for Penman-Monteith(PM)formula recommended by FAO to calculate reference crop evapotranspiration(ET0-PM).The influence analysis of solar radiation(Rs-c)from Angstrom equation and its parameters on ET0-c calculation based on PM was taken as the objective in nine agricultural regions of China.Using monthly valid average solar radiation(Rs-o)(from dataset of monthly values of radiation data from Chinese Surface Stations)and relative sunshine duration data(from dataset of monthly values of climate data from Chinese Surface Stations)at 112 stations during Jan.1957—Mar.2017,through comparative analysis and correlation analysis,the spatiotemporal differences between Rs-c and Rs-o were mainly explored.Then the spatiotemporal differences between ET0-c and ET0-o were obtained by input Rs-c and Rs-o to PM respectively,and it was also analyzed for illustrating the applicability of Rs-c to ET0-PM calculation in different regions of China.The result showed that Rs-c and Rs-o in the nine agricultural regions had significant and unstable spatial and temporal differences.There may be a large error when Rs-c directly replaced Rs-o to participate in the calculation of ET0-PM.However,the analysis of the spatiotemporal difference of ET0-c and ET0-o showed that whether in the entire continent,or the agricultural regions,ET0-c and ET0-o were characterized by a significant and relatively stable linear correlation,the R2 was more than 0.67 and the error of mean ET0-c was only 0.06~0.26 mm/d.Considering China s agricultural region types,dealing with the“spring drought”in the northern area of irrigation demand,the application can be directly to get ET0-PM by Rs-c,but for the“summer drought”period nationally,ET0-c was slants bigger than ET0-o,and the corresponding correction model was necessary in the application of high precision of water-saving agriculture.