# Combination of Models to Generate the First PAR Maps for Spain
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & \begin{tabular}{c} **Alava-** \\ **NEIKER** \\ \end{tabular} & \begin{tabular}{c} **Albacete-** \\ **ITAP** \\ \end{tabular} & \begin{tabular}{c} **Astruias-** \\ **SERIDA** \\ \end{tabular} & \begin{tabular}{c} **Cordoba-** \\ **IFAPA** \\ \end{tabular} & \begin{tabular}{c} **Lugo-** \\ **USC** \\ \end{tabular} & \begin{tabular}{c} **Salamanca-** \\ **CIALE** \\ \end{tabular} & \begin{tabular}{c} **Zaragoza-Aula** \\ **Dei** \\ \end{tabular} \\ \hline \multirow{4}{*}{CM-SAF model} & Slope & 0.93 & 0.92 & 0.91 & 0.93 & 0.94 & 0.96 & 0.89 \\  & Intercept & 13.23 & 13.72 & 16.05 & 12.13 & 15.84 & 16.77 & 13.22 \\  & R\({}^{2}\) & 0.997 & 0.997 & 0.995 & 0.997 & 0.987 & 0.987 & 0.998 \\  & MBE & 3.16 & 4.72 & 3.82 & 4.34 & 1.45 & 0.13 & 7.45 \\  & RMSE & 6.07 & 6.46 & 8.15 & 5.90 & 7.59 & 5.99 & 9.43 \\ \hline \multirow{4}{*}{MODIS model} & Slope & 1.02 & 1.01 & 0.96 & 1.02 & 1.01 & 1.04 & 0.99 \\  & Intercept & 2.99 & \(-1.60\) & 6.81 & 0.71 & 6.30 & 4.14 & 1.19 \\  & R\({}^{2}\) & 0.997 & 0.996 & 0.994 & 0.997 & 0.988 & 0.987 & 0.998 \\  & MBE & \(-2.75\) & \(-0.25\) & 1.32 & \(-1.91\) & \(-2.83\) & \(-4.63\) & 0.58 \\  & RMSE & 4.52 & 3.11 & 5.46 & 3.40 & 7.19 & 7.87 & 2.52 \\ \hline \multirow{4}{*}{\begin{tabular}{c} [PERSON] et al., \\ 2009 model \\ \end{tabular} } & Slope & 1.11 & 1.10 & 1.07 & 1.10 & 1.10 & 1.13 & 1.06 \\  & Intercept & 3.77 & 4.96 & 4.07 & 5.80 & 6.49 & 10.93 & 8.13 \\  & R\({}^{2}\) & 0.998 & 0.998 & 0.999 & 0.996 & 0.989 & 0.987 & 0.998 \\  & MBE & 12.18 & 10.87 & 8.38 & 11.10 & 12.32 & 16.02 & 8.32 \\  & RMSE & 14.12 & 11.96 & 9.79 & 12.31 & 15.64 & 18.60 & 9.26 \\ \hline \multirow{4}{*}{\begin{tabular}{c} [PERSON] et al., \\ 2012 pasture \\ model \\ \end{tabular} } & Slope & 1.00 & 0.98 & 0.97 & 0.99 & 0.99 & 1.02 & 0.96 \\  & Intercept & 31.81 & 35.05 & 31.96 & 34.60 & 35.83 & 38.17 & 36.25 \\  & R\({}^{2}\) & 0.998 & 0.998 & 0.999 & 0.996 & 0.987 & 0.986 & 0.998 \\  & MBE & 9.96 & 6.76 & 8.09 & 6.87 & 10.37 & 12.04 & 4.94 \\  & RMSE & 10.30 & 7.08 & 8.62 & 7.45 & 12.42 & 13.51 & 5.82 \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} [PERSON] et al., \\ 2012 forest \\ model \\ \end{tabular} } & Slope & 0.95 & 0.94 & 0.92 & 0.94 & 0.94 & 0.98 & 0.91 \\  & Intercept & 6.79 & 9.73 & 7.00 & 8.97 & 9.69 & 11.89 & 10.17 \\  & R\({}^{2}\) & 0.998 & 0.998 & 0.999 & 0.996 & 0.986 & 0.987 & 0.998 \\  & MBE & \(-2.63\) & \(-4.17\) & \(-5.59\) & \(-3.89\) & \(-2.80\) & 0.57 & \(-5.91\) \\  & RMSE & 4.64 & 5.41 & 7.86 & 5.32 & 8.15 & 5.91 & 7.67 \\ \hline \multirow{4}{*}{
\begin{tabular}{c} New model \\ \end{tabular} } & Slope & 0.99 & 1.00 & 0.99 & 1.00 & 0.99 & 0.99 & 1.00 \\  & Intercept & 2.28 & \(-0.07\) & 1.26 & \(-0.55\) & 1.74 & 3.70 & 1.28 \\ \cline{1-1}  & R\({}^{2}\) & 0.997 & 0.997 & 0.995 & 0.997 & 0.988 & 0.988 & 0.998 \\ \cline{1-1}  & MBE & 0.04 & \(-0.39\) & \(-0.17\) & 0.10 & \(-0.02\) & \(-0.38\) & 0.06 \\ \cline{1-1}  & RMSE & 3.19 & 2.54 & 4.38 & 2.47 & 6.21 & 5.71 & 2.25 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison between the results of the previous and new model on the seven stations. Note that the intercept is in μmol m\({}^{-2}\) s\({}^{-1}\), while the MBE and the RMSE are both in%. This phenomenon could be related to the slope of the terrain as the sensors of the optical images used to obtain satellite estimates experience difficulties with the angle of incidence of the reflectance [50; 51; 52]. The presence of snow can cause underestimations as well, as it could affect the reflectance. This indicates an aspect of this PAR model that requires improvement, which may become the subject of future study. These maps can be viewed and the PAR values for each location can be consulted at [[https://par.ceta-ciemat.es/en/geopar-maps/](https://par.ceta-ciemat.es/en/geopar-maps/)]([https://par.ceta-ciemat.es/en/geopar-maps/](https://par.ceta-ciemat.es/en/geopar-maps/)) (accessed on 15 October 2021). However, use is subject to the terms and conditions of the website.