## 5 Results and Discussion
### Effect of Individual Processing Steps on Soil Moisture Estimation
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**Mean R\({}^{2}\)**} & \multicolumn{4}{c}{**Mean uRMSE**} \\ \hline  & & **Test Site** & **IA** & **IA + FS** & **IA + FS + VA** & **IA** & **IA + FS** & **IA + FS + VA** \\ \hline \multirow{4}{*}{**Rur**} & Rur & 0.36 & 0.47 & 0.58 & 0.056 & 0.052 & 0.016 \\ \cline{2-10}  & Apulian Tavoliere 0.025 m & 0.36 & 0.39 & 0.44 & 0.058 & 0.058 & 0.056 \\ \cline{2-10}  & Apulian Tavoliere 0.1 m & 0.37 & 0.39 & 0.42 & 0.060 & 0.059 & 0.057 \\ \cline{2-10}  & Rur & 0.27 & 0.48 & 0.55 & 0.058 & 0.045 & 0.042 \\ \cline{2-10}  & Apulian Tavoliere 0.025 m & 0.15 & 0.16 & 0.49 & 0.081 & 0.081 & 0.059 \\ \cline{2-10}  & Apulian Tavoliere 0.1 m & 0.36 & 0.36 & 0.39 & 0.065 & 0.067 & 0.066 \\ \hline \multirow{4}{*}{**Rur**} & Rur & 0.47 & 0.57 & 0.68 & 0.054 & 0.047 & 0.041 \\ \cline{2-10}  & Apulian Tavoliere 0.025 m & 0.19 & 0.17 & 0.29 & 0.074 & 0.069 & 0.063 \\ \cline{2-10}  & Apulian Tavoliere 0.1 m & 0.29 & 0.27 & 0.39 & 0.069 & 0.066 & 0.063 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison between overall soil moisture retrievals from incidence angle normalized (IA), IA and Fourier Series transformed (IA + FS), and IA + FS and vegetational adapted (IA + FS + VA) SAR time series for each catchment and soil depth, with better performance indicated by a darker background color. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**R\({}^{2}\)**} & \multicolumn{4}{c}{**uRMSE [vol. \%]**} \\ \hline  & & **CRNP** & **IA** & **IA + FS** & **IA + FS + VA** & **IA** & **IA + FS** & **IA + FS** + VA** & **SM** & **VV** \\ \hline \multirow{4}{*}{**Rur**} & Rur\_C\_006 & 0.12 & 0.23 & 0.51 & 6.54 & 6.14 & 4.67 & 26.12 & 0.11 \\ \cline{2-10}  & Rur\_BC\_002 & 0.42 & 0.23 & 0.52 & 5.76 & 6.43 & 5.03 & 26.21 & 0.20 \\ \cline{2-10}  & ME\_BCK\_001 & 0.28 & 0.38 & 0.56 & 5.74 & 5.36 & 4.47 & 23.40 & 0.14 \\ \cline{2-10}  & SE\_C\_001 & 0.46 & 0.45 & 0.60 & 5.55 & **5.54** & **4.79** & 26.10 & 0.15 \\ \cline{2-10}  & Rur\_C\_006 & 0.37 & 0.38 & 0.51 & **4.25** & 4.51 & 3.85 & 21.69 & 0.11 \\ \cline{2-10}  & Rur\_BCK\_002 & 0.29 & 0.47 & 0.60 & 5.70 & 4.92 & 4.25 & 26.24 & 0.20 \\ \cline{2-10}  & ME\_BCK\_001 & 0.18 & 0.39 & 0.52 & 5.89 & 5.02 & 4.53 & 23.55 & 0.17 \\ \cline{2-10}  & SE\_C\_001 & 0.06 & 0.36 & 0.53 & 9.10 & 4.02 & 3.33 & 19.45 & 0.16 \\ \cline{2-10}  & Rur\_C\_006 & 0.54 & 0.54 & 0.80 & 4.21 & 4.43 & 2.89 & 23.14 & 0.16 \\ \cline{2-10}  & Rur\_BCK\_002 & 0.66 & 0.44 & 0.82 & 4.50 & 5.41 & 3.02 & 24.65 & 0.20 \\ \cline{2-10}  & ME\_BCK\_001 & 0.62 & 0.42 & 0.87 & 4.38 & 5.44 & 2.66 & 24.99 & 0.16 \\ \cline{2-10}  & SE\_C\_001 & 0.05 & 0.67 & 0.39 & 10.64 & 6.26 & 8.02 & 37.13 & 0.17 \\ \hline \multirow{4}{*}{**Rur**} & Rur\_C\_005 & 0.61 & 0.73 & 0.73 & 3.66 & 3.12 & 3.10 & 22.23 & 0.07 \\ \cline{2-10}  & Rur\_C\_007 & 0.28 & 0.65 & 0.65 & 6.55 & 5.34 & 5.34 & 30.86 & 0.08 \\ \cline{2-10}  & Rur\_BCK\_001 & 0.36 & 0.53 & 0.52 & 5.48 & 4.86 & 4.87 & 30.88 & 0.08 \\ \cline{2-10}  & Rur\_BCK\_001 & 0.31 & 0.58 & 0.58 & 5.61 & 4.46 & 4.44 & 28.73 & 0.09 \\ \cline{2-10}  & Rur\_C\_005 & 0.45 & 0.63 & 0.63 & 4.32 & 3.82 &stations RU_BCK_002 and ME_BCK_001 with R\({}^{2}\) values of 0.66 and 0.62, respectively. The highest uRMSE is observed in 2019 and 2020 at station SE_C_001 with 0.091 m\({}^{3}\)/m\({}^{3}\) and 0.106 m\({}^{3}\)/m\({}^{3}\), respectively. The lowest uRMSE values are observed in 2020 at the station RU_C_006 with 0.042 m\({}^{3}\)/m\({}^{3}\) and RU_BCDKR_001 with 0.043 m\({}^{3}\)/m\({}^{3}\) (Table 5). At the Apulian Tavoliere site, mean R\({}^{2}\) values of 0.15-0.36 and mean uRMSE of 0.058-0.081 m\({}^{3}\)/m\({}^{3}\) for a soil depth of 0.025 m, and mean R\({}^{2}\) values of 0.29-0.37 and mean uRMSE of 0.060-0.069 m\({}^{3}\)/m\({}^{3}\) for a soil depth of 0.1 m are achieved (Table 4).