## 3 Results
### Seasonal Cycle  
In an additional global level, we selected ten major biomes among the seventeen vegetation types defined by the IGBP to conduct the comparison. Figure 4 shows CLM4 generally captured the seasonal variations displayed by satellite-based FPAR. CLM4-FPAR and remote sensing FPAR have good correlation over the global and most biomes (Table 1). However, CLM4 FPAR generally has smaller seasonality and a shift during peak months. For savannas, CLM4 fails to capture the peak and trough months, and seasonality in CLM4 is less pronounced than in the satellite observations (Figure 4(i)). Savannas-dominated grids exist in the Sahel region, Southeast Africa and in the western part of South America. These areas are characterized by seasonal water availability, with most of their rainfall confined to one season. Correspondingly, we can see strong seasonality from the satellite observations (Figure 4(i)). However, this discrepancy in seasonality is possibly related to the model parameterization of LAI estimation rather than to the land surface solar radiation partitioning scheme. It should be noted that the model and remote sensing agree well in that the evergreen broadleaf forest retains a rather stable FPAR all year round, though the correlation between them is rather low due to discrepancies in anomalies. However, their anomalies vary through a range smaller than 0.05 (Figure 3(c)), which is consistent with the relatively stable phenology in tropical rainforest. Figure 3: The annual cycle of monthly mean gross primary production (GPP) from Bartlett Experimental Forest flux tower observations for the year 2005 and 2006. **Figure 4.** Comparison of 2003 to 2005 averaged seasonal cycle of FPAR anomalies between remote sensing and CLM4 FPAR at (**a**) global level and at biome level: (**b**) evergreen needleleaf forest, (**c**) Evergreen broadleaf forest is compared based on FPAR absolute value due to its special seasonality, (**d**) deciduous needleleaf forest, (**e**) deciduous broadleaf forest, (**f**) mixed forests, (**g**) open shrublands, (**h**) woody savannas, (**i**) savannas, (**j**) grassland, (**k**) croplands. **Table 1.** Correlation coefficient \(\gamma\) with P-value between CLM4-FPAR and satellite-observed FPAR annual cycle from 2003 to 2005. \begin{tabular}{c c c c c c c c c} \hline  & \multicolumn{2}{c}{**GIMMS3g**} & \multicolumn{2}{c}{**MODIS**} & \multicolumn{2}{c}{**SeaWiFS**} & \multicolumn{2}{c}{**MERIS**} \\  & \(\gamma\) & p-value & \(\gamma\) & p-value & \(\gamma\) & p-value & \(\gamma\) & p-value \\ \hline Global & 0.953 & 3.36E-04 & 0.942 & 3.34E-04 & 0.894 & 8.65E-06 & 0.873 & 9.25E-05 \\ Evergreen Needle Leaf Forest & 0.86 & 0.66 & 0.86 & 3.28E-04 & 0.934 & 0.96 & 0.893 & 0.44 \\ Evergreen Broad Leaf Forest & 0.14 & 2.35E-05 & \(-\)0.860 & 4.10E-06 & \(-\)0.016 & 4.11E-07 & 0.246 & 5.25E-06 \\ Deciduous Needle Leaf Forest & 0.919 & 1.90E-05 & 0.944 & 1.91E-04 & 0.965 & 1.57E-05 & 0.941 & 6.61E-06 \\ Deciduous Broad Leaf Forest & 0.923 & 1.78E-05 & 0.875 & 2.92E-05 & 0.926 & 2.09E-05 & 0.938 & 4.34E-05 \\ Mixed Forest & 0.924 & 1.92E-07 & 0.916 & 4.78E-07 & 0.921 & 1.35E-08 & 0.908 & 1.01E-08 \\ Open Shrublands & 0.97 & 1.96E-02 & 0.964 & 2.56E-05 & 0.982 & 1.22E-04 & 0.983 & 2.55E-04 \\ Woody Savannas & 0.66 & 0.94 & 0.918 & 0.90 & 0.887 & 0.28 & 0.868 & 0.11 \\ Savannas & 0.024 & 1.80E-06 & 0.042 & 1.51E-06 & 0.341 & 1.35E-05 & 0.487 & 1.58E-05 \\ Grassland & 0.952 & 2.07E-06 & 0.954 & 1.13E-05 & 0.928 & 8.99E-05 & 0.926 & 2.43E-04 \\ Croplands & 0.953 & 1.70E-06 & 0.942 & 4.59E-06 & 0.894 & 8.83E-05 & 0.873 & 2.12E-04 \\ \hline \end{tabular}