## 2 Study Area and Data
### Landsat 8 Imagery and MODIS ET Products  
A total of 32 Landsat 8 Level 1 (L1T) images with minimum cloud cover (<5% within the study area) during the year 2013-2014 were obtained from USGS Global Visualization Viewer ([[http://glovis.usgs.gov/](http://glovis.usgs.gov/)]([http://glovis.usgs.gov/](http://glovis.usgs.gov/))), including 11 images over Site 1 from 3 June 2013 to 25 August 2014; 15 images over Site 2 from 16 April 2013 to 9 August 2014, and three images over each of Sites 3 and 4 during the growing season (Figure 2, Table 1). Because of the geometric excellence of Landsat 8 OLI and TIRS images [32], all images had geometric accuracy, _i.e._, root mean square error (RMSE) less than 1 pixel. A subset of each image was extracted to cover a variety of land cover types and less non-vegetated area.  
Figure 1: Location of the study Sites 1, 2, 3 and 4 over (**a**) US and (**b**) South Korea.  
Figure 2: _Cont._  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Site No.**} & \multicolumn{2}{c}{**Landsat 8 Imagery**} & \multicolumn{2}{c}{**MOD16A2 Products**} \\ \cline{2-4}  & **Path/Row** & **Acquisition Dates** & **H/V** & **Starting Dates** \\ \hline \multirow{8}{*}{1} & & 06/03/2013 & 06/02/2013 \\  & & 08/06/2013 & 08/05/2013 \\  & & 09/07/2013 & 09/06/2013 \\  & & 09/23/2013 & 09/22/2013 \\  & & 10/09/2013 & 10/08/2013 \\  & & 10/25/2013 & 10/05 & 10/24/2013 \\  & & 11/26/2013 & 11/25/2013 \\  & & 04/19/2014 & 04/15/2014 \\  & & 05/05/2014 & 05/01/2014 \\  & & 07/24/2014 & 07/20/2014 \\  & & 08/25/2014 & /08/21/2014 \\ \hline \multirow{8}{*}{2} & & 04/16/2013 & 04/15/2013 \\  & & 06/03/2013 & 06/02/2013 \\  & & 06/19/2013 & 06/18/2013 \\  & & 07/21/2013 & 07/20/2013 \\  & & 08/22/2013 & 08/21/2013 \\  & & 09/07/2013 & 09/06/2013 \\  & & 09/23/2013 & 09/22/2013 \\  & & 11/10/2013 & 8/5 & 11/09/2013 \\  & & 12/12/2013 & 12/11/2013 \\  & & 03/18/2014 & 03/14/2014 \\  & & 04/19/2014 & 04/15/2014 \\  & & 06/06/2014 & 06/02/2014 \\  & & 06/22/2014 & 06/18/2014 \\  & & 07/24/2014 & 07/20/2014 \\  & & 08/09/2014 & 08/05/2014 \\ \hline \multirow{8}{*}{3} & & 05/11/2013 & 05/09/2013 \\  & & 06/28/2013 & 28/5 & 06/26/2013 \\  & & 09/16/2013 & 09/14/2013 \\ \hline \multirow{8}{*}{4} & & 06/05/2013 & 06/02/2013 \\  & & 10/27/2013 & 28/5 & 10/24/2013 \\ \cline{1-1}  & & 11/12/2013 & 11/09/2013 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Landsat 8 images and MOD16A2 products for all sites.  
Figure 2: Landsat 8 OLI color-infrared images for: (**a**) Site 1, image collected on 6 August 2013; (**b**) Site 2, image collected on 21 July 2013; (**c**) Site 3, image collected on 11 May 2013; and (**d**) Site 4, image collected on 5 June 2013. Yellow outlines show the boundary of the study area, blue rectangles show the areas around flux towers of sites 2 and 4, and green triangles indicate the location of flux towers.  
MODIS ET product, specifically MOD16A2, provides global ET, latent heat flux (LE), potential ET (PET), potential LE (PLE) datasets, and the quality control flag of ET (ET_QC) for each 8-day interval (5-day or 6-day for the end of the year) at 1 km resolution from the year 2000 to 2014 [33]. MOD16A2 ET is the sum of ET during each 8-day time periods within a year (mm/8 days, mm/5 days or mm/6 days for 361 composite data). In this study, the datasets covering Landsat image dates were selected, with starting dates of 1-4 days before the Landsat image was acquired (Table 1). ET and ET_QC layers were subset within the study area boundary, and the quality flag layer was used to exclude low quality ET. All ET products were re-projected to be the same projection system with Landsat 8 imagery, _i.e._, UTM WGS 1984 14N for Site 1, 10N for Site 2 and 52N for Sites 3 and 4.