## 3 Results
### Salinas Beach  
The SAR-SLs in Salinas are extracted from 773 SAR images (ASC) and 726 images (DESC) acquired between January 2015 and September 2023. The RL is obtained using an innovative tool based on the Open Street Map (OSM) catalog, showing much more agreement with the Google Earth images [45]. The beach area is partitioned into 61 polygons, each spanning a width of 50 m. In contrast to the previous location, Salinas presents a complex situation (depicted in Figure 11). The consequence of the speckle due to the sea conditions is quite evident, as SL points span over a wider area (extending over 800 m from the RL, as shown in Figure 11a). This poses a challenge to discerning the primary concentrations of SLs. Heatmap filtering (>0.2%) allows for a reduction in a significant part of the noise. The SLs obtained after applying the GMD filter are displayed in Figure 11b.  
Although there is an overlap between the ASC and DESC points, the lengths of certain polygons (length associated to the main SL concentration) exhibit disparities attributable to the scene's geometry. Along the eastern, urban part of the beach, ASC points are located more inland compared with DESC points, whereas the opposite occurs in the western part. Notably, geometry-related distortions such as shadows and layovers considerably impact the representation of SLs at this location. The longshore migration of crescentic bars in the inter-tidal area of Salinas beach complicates the analysis of the evolution of topographic contour lines, and consequently, it is difficult to relate the changes in the shoreline planform shape due to erosional or accretional processes over time. These complex 3D morphologies dominate most of Salinas beach (profiles No. 10 to No. 61 in Figure 12). However, on the western and eastern boundaries of the beach, where coastal morphodynamics are  
Figure 10: Profile format comparison between DSAS and SAR CRs. Annual SL CRs were calculated for each polygon using the two methodologies described previously. The profiles show very strong agreement between SAR ASC and DESC tracks and strong agreement between DSAS and SAR change rates.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **N** & \(\mathbf{R^{2}}\) & **MAE** & **MAE (WLR \textless{}0)** & **MAE (WLR \textgreater{}0)** \\ \hline SAR ASC/ & 93 & 0.97 & 0.37 & - & - \\ SAR DESC & 93 & 0.90 & 0.75 & 0.83 & 0.70 \\ VL DSAS/ & 93 & 0.92 & 0.84 & 0.80 & 0.86 \\ SAR DESC & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 5: Shoreline annual CR linear correlation indices among SAR ASC, SAR DESC, and DSAS VL.  
constrained due to the rocky headland and inlet groin, respectively, most changes in the shoreline position can be attributed to a net accumulation or loss of sediments in the beach profile.  
All analyses for Salinas beach are associated with changes observed in the eastern boundary of the beach (profiles No. 1 to No. 9 in Figure 12). The orientation of beach profiles No. 1 to No. 3 is significantly oblique with respect to the average orientation of Salinas beach, thus profile No. 6 is selected as the central transect of the eastern boundary, and it is considered representative of this part of the beach. After filtering, for this profile, from all the available SAR images, 684 ASC and 630 DESC SL positions (\(d_{M}\)) are used to assess both the seasonal and inter-annual migration of the SAR-SL in the cross-shore direction.