## Appendix B  
ETMonitor contains different modules to parameterize water flux components from soil-vegetation canopy, bare soil, open water, and ice and snow surfaces [32; 33; 64; 65], and total ET (in a broader definition) is the sum of the components. The applications of ETMonitor can also be found in [65; 66; 67; 91]. For this study, the results of ET in agroecosystems (soil-vegetation canopy) by ETMonitor were used. ETMonitor used the Shuttleworth-Wallace dual-source model [97], combined with parameterizations of a series of resistances, to estimate soil evaporation and vegetation transpiration for soil-vegetation canopy, and the total ET was calculated as the sum of soil evaporation and transpiration of crop plants. The soil evaporation (\(E_{s}\)) and plants transpiration (\(T_{v}\)) were estimated as  
\[E_{s}=\frac{\Delta(Rn_{s}-G)+\rho c_{p}D_{0}/r_{a}^{s}}{\lambda\Delta+\lambda \gamma(1+r_{s}^{s}/r_{a}^{s})}\] (A1)  
\[T_{v}=\frac{\Delta Rn_{c}+\rho c_{p}D_{0}/r_{a}^{c}}{\lambda\Delta+\lambda \gamma(1+r_{s}^{c}/r_{a}^{c})}\] (A2)  
where \(Rn_{c}\) (W\(\cdot\)m\({}^{-2}\)) is net radiation flux absorbed by the vegetation canopy; \(Rn_{s}\) (W\(\cdot\)m\({}^{-2}\)) is net radiation flux arrives at the soil surface; \(G\) is the soil heat flux (W m\({}^{-2}\)); \(r_{a}^{c}\) is the bulk boundary layer resistance of the vegetation (s m\({}^{-1}\)), estimated according to the canopy height; \(r_{s}^{c}\) is the bulk stomatal resistance of the canopy (s m\({}^{-1}\)), estimated by Jarvis-type model [92; 98]; \(r_{a}^{s}\) is the aerodynamic resistance between the soil surface and the canopy source height (s m\({}^{-1}\)); \(r_{s}^{s}\) is the surface resistance of the soil (s m\({}^{-1}\)); \(\Delta\) is the slope of the saturation vapor pressure curve of the air temperature (kPa K\({}^{-1}\)); \(\rho\) is the air density (kg m\({}^{-3}\)); \(c_{p}\) is the specific heat of air (J kg\({}^{-1}\) K\({}^{-1}\)); \(D_{0}\) is the water vapor pressure deficit at the canopy source height (kPa); \(\lambda\) is the latent heat of evaporation (J kg\({}^{-1}\)); \(\gamma\) is the psychrometric constant (kPa K\({}^{-1}\)). Details on ETMonitor and its regional applications can be found in our previous studies [32; 64; 65].  
The net radiation (\(Rn\)) is estimated from the incoming and outgoing radiation fluxes in shortwave and longwave, and total \(Rn\) was partitioned to \(Rn_{c}\) and \(Rn_{s}\) following:  
\[Rn=(1-\alpha)R_{S\downarrow}+R_{L\downarrow}-R_{L\uparrow}-(1-\varepsilon_{s}) R_{L\downarrow} \tag{10}\]  
where \(\alpha\) is surface albedo; \(R_{S\downarrow}\) is incoming shortwave radiation (W m\({}^{-2}\)); \(R_{L\downarrow}\) is incoming longwave radiation (W m\({}^{-2}\)); \(R_{L\uparrow}\) is outgoing longwave radiation (W m\({}^{-2}\)); \(\varepsilon_{s}\) is broadband surface emissivity. In addition, the interception loss amount was estimated by a revised Gash analytical model, and the details can be found in our previous study [99].  
The daily \(G\) in ETMonitor was estimated by a machine learning algorithm established based on in situ measurements of \(G\) and several explanatory variables, and the results of \(G\) showed good agreement with the ground measurements at flux tower sites.  
The ETMonitor was applied in combination with multi-source remote sensing data and re-analysis data from ERA5 to obtain global ET product at daily temporal and 1 km spatial resolutions in the last two decades. Applications of ETMonitor ET products can be found in [65; 66; 67].