## 3 Results and Discussion
The wave risk index (Figure 6b) shows close to 1 in most of the area, apart from the northwest region, where values of 0.5 are shown. It is noticeable that the lowest risk values (the worst risk conditions) in both wind and wave energy resources occur in the same region, the northwest section of the study area. This is precisely the region with the highest values of W\({}_{\rm ann}\), RLO, and WP indices. The cost category, represented by DC (Figure 7a) and WD (Figure 7b) is the same for both wind and wave resources, since they only depend on topographic constraints. Figure 4: Variability indices for wind energy resource. Variation coefficient (**a**) and monthly variability (**b**) in the NW Iberian Peninsula for the near future (2026–2045). The classification indices calculated following Equation (5) for wind and Equation (6) for waves are shown in Figure 8. The Wind index (C\({}_{\rm wind}\), panel a) shows elevated values (>0.6 in most of the area). Only a very narrow fringe along the cost shows values lower than 0.5. High values can be observed in a wider fringe (\(\sim\)50 km wide) along the coast, the highest ones being (around 0.7) observed from Cape Sao Vicente to Cape Roca. The wave classification index (C\({}_{\rm wave}\), panel b) shows the same pattern as the one observed for the wind index but with lower values (between 0.4 and 0.7) in the whole region. In this case, the coastal fringe with the highest values covers from Cape Roca to approximately Cape Pena. Figure 5: Variability indices for wave energy resource. Variation coefficient (**a**) and monthly variability (**b**) in the NW Iberian Peninsula for the near future (2026–2045). Figure 6: Risk indices for wind (**a**) and wave (**b**) energy resource in the NW Iberian Peninsula for the near future (2026–2045). The patterns observed in Figure 8 are similar to the ones depicted in Figures 9 and 10 obtained through the sensitivity analysis described in Section 2.3.5. In particular, Figures 9a and 10a calculated with Equation (15) are similar to Figure 8a,b, respectively. The RMSE values (Figures 9b and 10b) obtained from Equation (13) are at least one order of magnitude smaller than the average classification indices. This fact is corroborated by the distribution of the RMSE\({}_{\text{j}}\) calculated from Equation (14) (Figures 9c and 10c). Figure 8: Classification of the wind (**a**) and wave (**b**) energy resource in the NW Iberian Peninsula for the near future (2026–2045). Figure 7: Cost indices: (**a**) distance to coast (DC), and (**b**) water depth (WD) for wind and wave energy resources in the NW Iberian Peninsula for the near future (2026–2045). Figure 10: Sensitivity analysis for wave energy. **(a)** Map of the mean classification index, \(\langle\mathrm{C}_{j}^{k}\rangle\) calculated from Equation (15); **(b)** Map of the RMSE\({}^{k}\) calculated from Equation (14); and **(c)** RMSE\({}_{j}\) histogram calculated from Equation (13). Figure 9: Sensitivity analysis for wind energy. **(a)** Map of the mean classification index, \(\langle\mathrm{C}_{j}^{k}\rangle\) calculated from Equation (15); **(b)** Map of the RMSE\({}^{k}\) calculated from Equation (14); and **(c)** RMSE\({}_{j}\) histogram calculated from Equation (13). The combined index (CI) to classify the hybrid wind-wave energy resource (Figure 11) shows strong similarities to the patterns observed in Figure 2:0 In general, the CI is lower than C\({}_{\text{wind}}\) (Figure 8a) and higher than C\({}_{\text{wave}}\) (Figure 8b). The narrow coastal fringe with low values, and the wider coastal fringe with high values (from Cape Penas to Cape Sao Vicente) can also be observed in this case. Once again, the lowest values, around 0.5, are observed in the Gulf of Cadiz.