## 3 Results and Discussion  
### Phase 1: Data Quality Control  
The initially available oil slick data archive is composed of 4,916 oil slick polygons--2021 oil seeps (41%) and 2895 oil spills (59%)--imaged with 277 RADARSAT-2 scenes (Table 2 I), all of which are 16-bit and VV polarized [19; 20; 21; 22]. These include two different RADARSAT beam modes--Wide [W1 and W2: 354 oil slicks (7%)] and ScanSAR Narrow [SCNA and SCNB: 4562 oil slicks (93%)]--that own two fundamental imaging differences: (1) W1 and W2 are Single Beam Modes (i.e., a strip-map SAR mode  
\begin{table} \begin{tabular}{|c|c|c|c|} \hline
**CRM.** & OF Oil Seep & Df Oil Sgil & Total Real \\ \hline Oil Seep Res & **A** & **B** & **A+B** \\ Oil Seep Res & **C** & **D** & **C+D** \\ \hline Total DF & **A+C** & **B+D** & **A+D+C** \\ \hline \end{tabular} \begin{tabular}{|c|c|c|} \hline
**CM.2*** & DF Oil Seep & Df Oil Sgil & Total Real \\ \hline Oil Seep Res & **A/K+B** & **B/(+B)** & 100\% \\ Oil Seep Res & **C/(C+D)** & **C/(C+D)** & 100\% \\ \hline \end{tabular} \begin{tabular}{|c|c|c|} \hline
**CM.3*** & DF Oil Seep & Df Oil Sgil \\ \hline Oil Seep Res & **A/K+B** & **B/(+D)** \\ Oil Seep Res & **C/(A+C)** & **B/(B+D)** \\ \hline Total DF & 100\% & 100\% \\ \hline \end{tabular} \begin{tabular}{|c|c|} \hline
**Number of Samples (Isc.oil slicks)** \\ \hline A-O & Series: Constant Identification \\ B-O & Series: Max-Identification \\ C+A & C = Oil Sepls: This-Identification \\ D-O & Oil Sepls: Current identification \\ A+B+C+D = Oil Sticks (Isc.4,562) \\ \hline \end{tabular} \begin{tabular}{|c|c|} \hline
**Model** & **A+(A)** \\ \hline
**Parameter** & (C+(A) = Specfluidity) \\ C+A & **C+A** = Has Negative \\ Error & C/(C+(A) = False Positive \\ \hline
**A+B+ Oil Seeps (Isc.2,564)** \\ \hline
**Model** & **A/(A+C)** = Positive Predictive Value \\
**Accuracy** & (D+(B) = Inverse Predictive Value \\ \hline
**CM.3** & **B/(+D)** = Inverse of the Pos. Predict. Val. \\ error & C/(A+C)** = Inverse of the Pos. Predict. Val. \\ \hline \end{tabular} 
\begin{tabular}{|c|c|} \hline
**Model** & **A+C** = DF Oil Seeps \\ \hline
with certain imaging aspects constant along the entire scene), whereas SCNA and SCNB are ScanSAR Modes (i.e., combine two or more of the Single Beam Modes) [67]; the latter provides larger area coverage: swath width of 300 km--almost twice that of W1 and W2: 170 km and 150 km, respectively; and (2) Wide has a finer ground resolution of 25 m, which is \(\frac{1}{4}\) of the ScanSAR Narrow one: 50 m.  
Regarding their specification differences, eventual inaccuracies may be introduced to beam mode cross-comparisons. Notwithstanding that W1 and W2 provide better delineation of smaller oil slicks with their finer ground resolution, only SCNA and SCNB are kept in our analysis as these represent more than 90% of the available scenes. Furthermore, the ScanSAR Narrow swath width is more appropriate for monitoring applications requiring large-scale coverage such as the one that gave rise to the initially available oil slick data archive [19; 20; 21; 22]. In fact, the lower scene cost of using ScanSAR Narrow to monitor larger ocean regions is rather preferable than the smaller area coverage of the Wide images. Consequently, our workable dataset is composed of the collection of oil slick polygons imaged with the two ScanSAR Narrow beam modes: 4562 oil slicks--1994 oil seeps (44%) and 2568 oil spills (56%)--Table 2 II. Despite the fact that our EDA has 7% (354) fewer oil slicks than our previous study [19; 20; 21; 22], representing about 1% (27) fewer seeps and approximately 11% (327) fewer spills (Table 2 III), such data reduction results in a more balanced dataset as compared to the one explored in our previous investigations, i.e., a smaller difference between the number of analyzed spills and seeps: 13% instead of 18% (Table 2: I-II). Indeed, this provides a firmer basis in the oil-slick category discrimination.