Study sites and data
We obtained the gap-filled 30-min data, including the four components of radiation (DSR, USR, DLR, ULR; W∙m-2) and GPP (g∙C∙m-2∙time-1), of 54 sites with EC flux towers from FLUXNET (https://fluxnet.org), OZflux (http://www.ozflux.org.au) and ChinaFlux (http://www.chinaflux.org/) (Figure 2; Table S1). The dataset consists of a total of 267 site-years and covers a wide range of vegetation types, including tropical rainforests, subtropical evergreen forests, temperate deciduous forests, coniferous forests, shrub lands, savannas and grasslands, across North America, Europe, Asia and Australia. Each ecosystem type includes at least three sites in different regions to ensure its regional representativeness (Table S1). The instrumentation information of each site is also outlined in Table S1.