# A Simulation Study of Global Evapotranspiration Components Using the Community Land Model
## 3 Results Analysis
### Soil Evaporation  
Figure 8 shows the seasonal spatial patterns of the simulation results of CLM4.5 and the reanalysis data of global Es. As observed from Figure 8, CLM4.5 effectively simulates the seasonal variation of Es, but there is a large difference in the distribution of the high and low values between the simulation results of CLM4.5 and the reanalyzed data. Table 4 shows the RMSEs, means and spatial correlation coefficients of the simulated results of CLM4.5, and reanalysis data of global Es. From Table 4, it can be observed that the spatial correlation coefficients of the simulated Es in CLM4.5 and the reanalysis data in January, April, July, October, and annual average are 0.64, 0.52, 0.58, 0.53 and 0.53, respectively, which is smaller than that of Ec and Et, indicating that there are major differences in the spatial distribution of global Es between CLM4.5 and the reanalyzed data. Figure 9 shows the differences among the reanalysis data, CLM4.5, and CLM4.0. As observed from Figure 9a-d, the simulation results of CLM4.5 on Es in equatorial regions are significantly lower in comparison to the reanalysis data, which may be caused by the strong Et in those regions (see Figure 7a-d). The Es in most areas of the middle and high latitudes in the Northern Hemisphere is relatively low in January and July, while it is generally high in the southwest of Asia, southwest North America, northern Africa and most parts of the Southern Hemisphere. As seen from Table 4, the simulated means of Es in CLM4.5 in January, July and October are larger than the means in the reanalysis, and the mean of Es is smaller in April. The simulated mean in October (7.0 W/m\({}^{2}\)) is very close to the reanalysis data (6.9 W/m\({}^{2}\)), indicating that CLM4.5 has a relatively strong simulation ability for the mean of Es in October. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**RMSE (Units: W/m\({}^{2}\))**} & \multicolumn{2}{c}{**Mean (Units: W/m\({}^{2}\))**} & \multicolumn{2}{c}{**SCC**} \\ \hline  & **CLM4** & **CLM4.5** & **CLM4** & **CLM4.5** & **NOAA** & **CLM4** & **CLM4.5** \\ \hline January & 9.1 & 8.5 & 5.4 & 5.2 & 4.5 & 0.61 & 0.64 \\ April & 11.3 & 11.1 & 8.0 & 7.5 & 8.5 & 0.51 & 0.52 \\ July & 12.3 & 11.4 & 11.4 & 10.9 & 10.5 & 0.54 & 0.58 \\ October & 9.7 & 8.6 & 6.4 & 7.0 & 6.9 & 0.49 & 0.53 \\ Annual mean & 8.5 & 7.9 & 7.8 & 7.5 & 7.6 & 0.50 & 0.53 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: RMSEs, means and spatial correlation coefficients (SCC) for globally Es in January, April, July and October and annual mean. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**PFT Number** & **PFT Name** & **CLM4.0** & **CLM4.5** & **CLM4.5-CLM4.0** \\ \hline
16 & C3 dry land crops & 21.0 & 23.7 & 2.7 \\
11 & temperate deciduous shrubs & 7.6 & 8.9 & 1.3 \\
13 & boreal grassland & 6.8 & 7.3 & 0.4 \\
14 & C3 grassland & 6.1 & 7.4 & 1.4 \\
15 & C4 grassland & 23.1 & 24.7 & 1.6 \\
12 & north deciduous broad-leaved shrubs & 10.0 & 12.2 & 2.2 \\
5 & tropical evergreen broad-leaved forests & 54.9 & 43.4 & \(-\)11.5 \\
3 & northern evergreen coniferous forests & 9.0 & 11.1 & 2.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Annual mean of the Et (Unit: W/m\({}^{2}\)) of the dominant PFTs in CLM4.0 and CLM4.5 and their difference (CLM4.5-CLM4.0). From Figure 9i-l, it can be observed that the simulated Es in CLM4.5 is larger than that of CLM4.0 near the equator because the transpiration capacity of CLM4.5 is limited in the equatorial region. The bias distributions in Figures 9i-l and 7i-l are opposite of one another in most areas, especially in the Southern Hemisphere, which reflects the close relationship between Es and Et. That is, when the vegetation transpiration increases the soil moisture coefficient, the difference in humidity between the reference height and ground surface will decrease, resulting in a decrease in soil evaporation [15]. The error distributions of Figures 9e-h and 9i-l are also basically the opposite of one another.