Geochemical analysis of SAR backscattering (Sentinel-1) on global ocean oil spill cases

ABSTRACT

  The oil spill is one of the most impactful sources of marine pollution on the ocean surface, detected by the SAR sensors as dark areas, regions with low backscatter values. Due to the complex mixture of hydrophobic hydrocarbons, mineral oil spills change the water surface tension dampening the capillary gravity waves and provoking a specular reflection. In this work, we associated the geochemical oil characteristics, such as density, viscosity, API, and molecular composition with the backscatter values for each oil spill case. We identified the relationship between the oil weathering processes, with the changes in the backscattering values of ocean oil spills. The method designed zonal sections over the oil spills detected in the SAR images, to extract the backscatter values for each pixel along the section. The lowest backscatter average was observed by the heavy oil spill in the Corsica Island study (−29,99 dB). The highest level of weathering had the highest backscatter averages. Damping rates ranged between 4,12 and 7,07 dB and the backscatter values may be related to low oil layer thickness. Furthermore, low wind speeds may have reduced the contrast between water and oil spills, resulting in low damping ratios in all events.

KEYWORDS:

• Synthetic Aperture Radar (SAR)
• SAR processing
• oil spills
• radar backscatter
• normalized radar cross section
• damping ratio

Acknowledgments

We appreciate comments and suggestions from the anonymous reviewers that helped improve the quality and presentation of the manuscript.

Author contributions

Conceptualization, M.R.A.C., L.F.F.M.; methodology, M.R.A.C., L.F.F.M.; software execution, M.R.A.C., L.F.F.M.; writing – original draft preparation, M.R.A.C., L.F.F.M.; writing – review and editing, M.R.A.C., L.F.F.M., supervision, L.F.F.M., C.A.D.L., A.T.C.L. all authors have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The first author of this manuscript is grateful for the financial support of the Human Resources Program of the National Agency for Petroleum, Natural Gas and Biofuels (PRH/ANP – PRH36/UFBA), supported with resources from the investment of oil companies qualified in the P, D&I Clause of the ANP Resolution no.50/2015. This work is also funded by the CNPq/MCTI Nº06/2020 process 440852/2020-0, projects entitled “Detection, control and preventive remediation of accidents involving the oil and fuel transportation off the Brazilian coast”. The authors are grateful for the financial support of the Human Resources Program of the National Agency for Petroleum, Natural Gas and Biofuels (PRH/ANP – PRH36/UFBA), supported with resources from the investment of oil companies qualified in the P, D&I Clause of the ANP Resolution No. 50/2015.