Detection of Oil Spilled at Sea with Entropy and Alpha polarimetric in Sentinel-1 C-band SAR data: Lima-Peru case

The Sentinel-1 (S1) SLC-IW Synthetic Aperture Radar (SAR) contributes to ensuring global sustainability and environmental impact mitigation with early detection of Oil Spills at Sea (OSS), such as the one that occurred on January 15, 2022, Pampilla refinery, Ventanilla-Lima. This event was catalogued as the worst ecological disaster in recent times in Lima due to its high proportions causing serious environmental effects. The objective is to detect OSS with entropy (H) and polarimetric alpha angle (α) in S1A, SLC-IW, dual-pol data in VV + VH channels, Lima-Peru case. From the SLC product, the values of the covariance matrix components C₁₁, C₁₂, C₂₁ and C₂₂, to which the refined Speckle Lee polarimetric filter has been applied, are evaluated for their decomposition and determination of the polarimetric properties, such as H and α in the identification of areas with OSS. The results of S1A, January 25, 2022, from the threshold values of H (0.5–0.89) and α (10°–30°), are validated with the sampled points (SP) on that date. The Kappa index (κ) shows moderate agreement for H (κ = 0.49) and good agreement for α (κ = 0.61). For S1A, February 02, 2022, the threshold values of H (0.5–0.72) and α (10°–20°) are validated with the SP on that date, indicating very good agreement for H(κ = 0.85) and good agreement for α (κ = 0.76).