# Generation of High Resolution Vegetation Productivity from a Downscaling Method
## 3 Results
### Validation of Downscaled FPAR and LAI
#### 3.1.2 Comparison of FPAR and LAI Time Series  
Temporal dynamic patterns of the downscaled FPAR, GLASS FPAR and MODIS FPAR from 17 field observation sites, which were mainly covered by vegetation are shown in Figure 8. In general, the time series of the D_FPAR_GLASS, D_FPAR_MODIS, MODIS FPAR and GLASS FPAR agreed well in cropland, orchard, vegetable field and wetland. It could be clearly seen that GLASS FPAR was more continuous with smoother trajectories, therefore, D_FPAR_GLASS showed the same properties as GLASS FPAR, i.e., the time series was also continuous. FPAR time series increased initially then decreased after reaching the peak around July (DOY 185-216). In cropland, the D_FPAR_GLASS, D_FPAR_MODIS, MODIS FPAR and GLASS FPAR agreed better in August and September (DOY 217-280), but the GLASS FPAR was about 0.1-0.2 lower than the MODIS FPAR and downscaled FPAR in June, July and August. The MODIS FPAR could be as high as about 0.8 while the GLASS FPAR was only about 0.6 in the peak of growing season. MODIS FPAR was the highest in the whole growing season in vegetable land, as shown in Figure 7c, except for a low value that appeared in July (DOY 201-208), which led to a low value in the D_FPAR_MODIS. Time series of the GLASS FPAR and D_FPAR_GLASS in vegetable land were obviously more continuous. In orchard and  
Figure 6: Validation of downscaled FPAR against retrieved FPAR in July 2012: (**a**) Comparison of D_FPAR_GLASS and retrieved FPAR; (**b**) Comparison of D_FPAR_MODIS and retrieved FPAR. Retrieved FPAR means high resolution (30 m) FPAR retrieved by using an instantaneous quantitative model based on the law of energy conservation from Chinese HJ-1B data.  
Figure 7: Validation of downscaled LAI against retrieved LAI in July 2012: (**a**) D_LAI_GLASS and retrieved LAI; (**b**) Comparison of D_LAI_MODIS and retrieved LAI. Retrieved LAI means high resolution (30 m) LAI retrieved by using an instantaneous quantitative model based on the law of energy conservation from Chinese HJ-1B data.  
wetland, we could find that good agreements were generally achieved among D_FPAR_GLASS data, D_FPAR_MODIS, MODIS FPAR and GLASS FPAR generally. But in orchard, the MODIS FPAR was higher than the others in the early growing season.  
Generally, D_LAI_GLASS, D_LAI_MODIS, MODIS LAI and GLASS LAI agreed well in most times (Figure 9). We also found that time series of GLASS LAI and D_LAI_GLASS were more continuous with smoother trajectories. In cropland, GLASS LAI was less than 3 in June and July, which was lower than the MODIS LAI and the downscaled LAI. MODIS LAI and D_LAI_MODIS were a little lower than the GLASS LAI and D_LAI_GLASS in August and September in orchard. In the vegetable field, downscaled LAI, GLASS LAI and MODIS LAI achieved good agreements, but GLASS LAI was more continuous. In wetland, MODIS LAI was less than 3 in June and July, which was lower than the downscaled LAI and GLASS LAI.  
Figure 8: Comparison of MODIS FPAR, GLASS FPAR, D_FPAR_GLASS and D_FPAR_MODIS: (**a**) Cropland; (**b**) orchard; (**c**) vegetable field; (**d**) wetland. Note that the FPAR are the mean values of pixels from all sites in cropland.