资源环境科技发展态势分析平台

The daytime-mean solar zenith angle (SZA) and the solar insolation-weighted-mean SZA are discussed from a global scale and from a latitude-dependent local-scale perspective. It is found that the choosing of daytime-mean SZA or insolation-weighted-mean SZA depends on whether the averaging process is zeromoment or single-moment weighted. It is a misleading to state that the solar insolation-weighted-mean SZA is more accurate than the daytime-mean SZA when averaging a radiation variable, as claimed by Cronin.