## 3 Results
### Spatial Patterns of Estimated GPP
The seasonal pattern of global GPP revealed that the regions with the highest GPP were mainly in humid tropical areas such as the Amazon, Central Africa, and Southeast Asia, where both the temperature and moisture requirements for photosynthesis are adequately satisfied. Vegetation productivity in temperate regions was at an intermediate level, and vegetation productivity in cold and higher altitude regions was the lowest because temperature and or precipitation in these regions were limited. The GPP of different vegetation coverage types in each season in 2014 is shown in Figure 4 (note missing high latitude values). The GPP was highest in JJA, which was also related to the amount of data (GOSIF had fewer missing values at high latitudes for JJA). EBF had high GPP throughout the year, whereas GPP was always low for CSH, OSH, and WET. Comparing the statistics of the three GPP products for different vegetation coverage types, the barplot from the four seasons shows that the GPP of MODIS was low compared to the other two GPP products. In DJF, the EBF GPP reached as high as 189.30 g C\(\cdot\)m\({}^{-2}\)(GPP\({}_{\text{SIF}}\)), 157.89 g C\(\cdot\)m\({}^{-2}\)(GPP\({}_{\text{MODIS}}\)), and 206.72 g C\(\cdot\)m\({}^{-2}\)(GPP\({}_{\text{GLASS}}\)), with a difference of up to 48.83 g C\(\cdot\)m\({}^{-2}\) between the three products. Except for ENF, GPP\({}_{\text{MODIS}}\) was the lowest among the three products across different vegetation coverage types. The GPP\({}_{\text{SIF}}\), GPP\({}_{\text{MODIS}}\), and GPP\({}_{\text{GLASS}}\) of CRO were all almost equal (28.48 g C\(\cdot\)m\({}^{-2}\), 27.60 g C\(\cdot\)m\({}^{-2}\), and 29.49 g C\(\cdot\)m\({}^{-2}\), respectively). In MAM, the GPP of ENF, EBF, DBF,  
Figure 3: Spatial patterns of global GPP in different seasons of 2014: (**a**) GPP\({}_{\text{SIF}}\) in December, January, and February (DJF); (**b**) GPP\({}_{\text{MODIS}}\) in DJF; (**c**) GPP\({}_{\text{GLASS}}\) in DJF; (**d**) GPP\({}_{\text{SIF}}\) in March, April and May (MAM); (**e**) GPP\({}_{\text{MODIS}}\) in MAM; (**f**) GPP\({}_{\text{GLASS}}\) in MAM; (**g**) GPP\({}_{\text{SIF}}\) in June, July, and August (JJA); (**h**) GPP\({}_{\text{MODIS}}\) in JJA; (**i**) GPP\({}_{\text{GLASS}}\) in JJA; (**j**) GPP\({}_{\text{SIF}}\) in September, October, and November (SON); (**k**) GPP\({}_{\text{MODIS}}\) in SON; (**l**) GPP\({}_{\text{GLASS}}\) in SON. MF, SAV, and WSA all exceeded 100 g C\(\cdot\)m\({}^{-2}\). GPP\({}_{\rm GLASS}\) was also higher than GPP\({}_{\rm SIF}\) regarding EBF while the GPP of MODIS was higher than the other two GPP products in CSH and OSH. The GPP\({}_{\rm SIF}\), GPP\({}_{\rm MODIS}\), and GPP\({}_{\rm GLASS}\) of OSH were similar (22.00 g C\(\cdot\)m\({}^{-2}\), 22.57 g C\(\cdot\)m\({}^{-2}\), and 19.97 g C\(\cdot\)m\({}^{-2}\), respectively). During JJA, the GPP of CSH, OSH, GRA, and WET did not exceed 150 g C\(\cdot\)m\({}^{-2}\). Among the different vegetation coverage types, the GPP\({}_{\rm SIF}\) and GPP\({}_{\rm GLASS}\) were all almost equal in EBF, DBF, MF, CSH, and CRO. For EBF, the differences between the three products were the smallest in a year. The GPP\({}_{\rm SIF}\), GPP\({}_{\rm MODIS}\), and GPP\({}_{\rm GLASS}\) of CSH were all almost equal (118.07 g C\(\cdot\)m\({}^{-2}\), 114.89 g C\(\cdot\)m\({}^{-2}\), and 118.88 g C\(\cdot\)m\({}^{-2}\), respectively). During SON, the GPP of each vegetation coverage type decreased to a certain extent, compared with the previous season. The GPP of ENF, DNF, CSH, OSH, and WET were almost below 100 g\(\cdot\)m\({}^{-2}\). The GPP\({}_{\rm SIF}\) and GPP\({}_{\rm GLASS}\) of EBF, DBF, MF, CSH, OSH, and WET were all very similar, which was in clear contrast with GPP\({}_{\rm MODIS}\). For CSH and OSH, GPP\({}_{\rm SIF}\), GPP\({}_{\rm MODIS}\), and GPP\({}_{\rm GLASS}\) were almost equal.