## 4 Results
### Spatial Variation of the Downscaled ET Product  
It is obvious that the Landsat-scale ET map in Figures 7 and 8 showed more spatial details than coarse resolution ET. Zoomed views of Landsat downscaled ET at Site 2 (Figure 9) also demonstrated that the product was able to represent the spatiotemporal dynamics of ET at the patch level, with different patches showing varying trends of ET change.  
Figure 8: MODIS 8-day ET, Landsat 1 km ET and downscaled Landsat 30 m ET in the southwest part of Site 3 (refer to Figure 2f blue outline for the area boundary) during the year of 2013.  
In order to evaluate the improvement of spatial information represented by the downscaled ET, the differences between the 30 m and 1 km MODIS ETs within the corresponding 1 km grids was calculated and the statistics of the differences was analyzed for each land cover type. First, a 1 km land cover layer was generated using 30 m land cover products. The USGS National Land Cover Database (NLCD) 2011 [70] was used for US sites and three land cover products (MODIS Global 500m Terra and Aqua combined land cover product (MCD12Q1 IGBP) [71], European Space Agency (ESA) Global Land Cover Map 2009 product (GlobCover 2009) [72], and the Finer Resolution Observation and Monitoring of Global Land Cover (FROM-GLC) [73] were combined for Korea sites to ensure accurate land cover information [27]. The three products were combined to create a new ensemble 30 m land cover data only using the pixels that agreed from all three land cover layers. Grids with pure land cover types, _i.e._, a single land cover occupying over 80% of the 1 km grid area were selected for further analysis. Boxplots in Figure 10 show the distribution of the differences between 30 m Landsat downscaled ET and MODIS ET within crop, forest, grass, and shrub land. For all sites, the median of the differences was around zero, indicating an overall unbiased estimation of ET using MODIS ET as a reference. Dispersion of the biases against MODIS ET increased from spring to summer and decreased during winter, implying that the downscaled ET revealed a higher spatial variation during growing seasons. At Site 1, the majority of the differences (25 th-75 th percentile) was within \(\pm\)5 mm/8 days, and the extreme difference values were around \(\pm\)10 mm/8 days. Cropland and forests showed a slightly greater dispersion of the differences than grassland. At Site 2, the difference values were on average within \(\pm\)5 mm/8 days; the extreme values were on average \(\pm\)20 mm/8 days at croplands and forest, and \(\pm\)6 mm/8 days at grassland and shrub area. Sites 3 and 4 showed a similar pattern. For both sites, the majority of the differences (25 th-75 th percentile) were within \(\pm\)10 mm/8 days, and the extreme difference values were around \(\pm\)20 mm/8 days. Dispersion of the biases considerably decreased during the leaf-off season for Site 4, while it was maximized in the middle of the growing season for Site 3.  
Figure 9: Zoomed view of Landsat 30 m downscaled ET (mm/8-days) in the northeast part of Site 2 during the year of 2013.  
Figure 10: Cont.  
Figure 10: Boxplots of difference between Landsat downscaled 30 m ET and MODIS ET in forest, crop, shrub and grass areas for: (**a**) Site 1; (**b**) Site 2; (**c**) Site 3; and (**d**) Site 4.