## 5 Results
### Satellite Product Intercomparison
#### 5.1.3 Spatio-Temporal Consistency  
The overall spatio-temporal consistency between PROBA-V SA v1.0 and the reference products is assessed over the LANDVAL network sites considering all good quality observations according to the quality flags (see Table 3). * PROBA-V SA v1.0 versus SPOT/VGT SA v1.0 (overlap period)  
For the visible domain (Figure 8a-d and Table 9), PROBA-V SA v1.0 tends to provide slightly lower values than SPOT/VGT SA v1.0, with small negative mean biases of \(-2.2\%\) and \(-2.8\%\) for black-sky and white sky albedos, respectively. Optimal lineal regression relationships from the MAR were found (offset \(\sim\)0 and slope close to 1). Worse results were found in terms of the RMSD (uncertainty), with values of approximately 0.05 (\(\sim\)35%). For the near-infrared (Figure 8b-e and Table 9), positive biases (PROBA-V SA v1.0 \(>\) SPOT/VGT SA v1.0) of 2.3-2.4% were found, with an RMSD of approximately 10% and high correlations (\(>\)0.94). PROBA-V SA v1.0 tends to provide higher values than SPOT/VGT SA v1.0 for albedo values lower than 0.5 and the opposite trend for albedo values higher than 0.5 (typically snow cases). In all cases, a median bias close to zero was found, which was within the optimal level of consistency. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**PROBA-V SA v1.0 vs. SPOT/VGT SA v1.0 (Dec 2013–May 2014)**} \\ \cline{2-7}  & **AL-DH-VI** & **AL-DH-NI** & **AL-DH-BB** & **AL-BH-VI** & **AL-DH-NI** & **AL-BH-BB** \\ \hline
**Median\_Err** & 0.01 & 0.014 & 0.01 & 0.013 & 0.02 & 0.014 \\
**(Median\_Err \%)** & (8\%) & (5\%) & (4.7\%) & (10\%) & (6.3\%) & (5.9\%) \\ \hline
**Bias** & \(-\)0.003 & 0.007 & 0.002 & \(-\)0.024 & 0.007 & 0.002 \\
**(Bias \%)** & (2.2\%) & (2.3\%) & (0.9\%) & (2.8\%) & (2.4\%) & (1.0\%) \\ \hline
**RMSD** & 0.044 & 0.031 & 0.032 & 0.047 & 0.037 & 0.036 \\
**(RMSD \%)** & (35.3\%) & (10.5\%) & (14.5\%) & (36.1\%) & (11.7\%) & (15.2\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Main performance statistics of C3S PROBA-V SA v1.0 versus SPOT/VGT SA v1.0 broadband albedo products over all LANDVAL sites during December 2103 to May 2014 period. The computation was performed over good quality pixels according to PROBA-V and SPOT/VGT QFLAGS. Remarkably low mean biases (<1%) were found for the total shortwave (Figure 8c-f and Table 9), as well as high correlations (>0.93). Total uncertainties (RMSD) of 0.03 (~15%) were found. A systematic positive bias was found for almost all ranges, except for values lower than 0.1 and higher than 0.7, with the median bias typically within the optimal (GCOS) level of consistency (Table 6). * PROBA-V SA v1.0 versus MCD43A3 C6 (2014 year)  
Positive bias (PROBA-V SA v1.0 > MCD43A3 C6) of ~5% was found for the visible domain (Figure 9a-d and Table 10) with uncertainties (RMSD) lower than 0.05. Box-plots show slight median positive bias for albedo ranges up to 0.4, which is the range where most of the samples are located in this spectral domain. Large discrepancies were found for the highest ranges, mainly affected by snow cases, with a tendency towards the negative sign of the bias. PROBA-V SA v1.0 tends to provide higher values than MCD43A3 C6 (~8-9%) for the near-infrared (Figure 9b-e and Table 10), with overall RMSD of approximately 14-15%. PROBA-V SA v1.0 tends to provide higher values than MCD43A3 C6 for albedo values lower than 0.5, and the opposite trend for albedo values higher than 0.5. Figure 8: Top: C3S PROBA-V SA v1.0 versus C3S SPOT/VGT SA v1.0 products’ scatter-plots, where the dashed lines correspond to the optimal, target and predefined threshold uncertainty levels around the 1:1 relation (continuous line). Bottom: Box-plots of the bias per bin albedo range, where red bars indicate the median values, blue boxes stretch from the 25 th percentile to the 75 th percentile of the data and whiskers include 99.3% of the coverage data (\(\pm\)2.7 \(\sigma\)). Outliers are not displayed.