Impacts of oil spills on altimeter waveforms and radar backscatter cross-section

Type Article
Date 2017-05
Language English
Author(s) Cheng Yongcun1, Tournadre Jean2, Li Xiaofeng3, Xu Qing4, Chapron BertrandORCID2
Affiliation(s) 1 : Old Dominion Univ, Ctr Coastal Phys Oceanog, Norfolk, VA 23529 USA.
2 : Univ Bretagne Occidentale, CNRS, IFREMER, Lab Oceanog Phys & Spatiale, Plouzane, France.
4 : Hohai Univ, Coll Oceanog, Nanjing, Jiangsu, Peoples R China.
Source Journal Of Geophysical Research-oceans (2169-9275) (Amer Geophysical Union), 2017-05 , Vol. 122 , N. 5 , P. 3621-3637
DOI 10.1002/2016JC012568
WOS© Times Cited 13
Keyword(s) oil spill, altimeter, sigma0 bloom, waveform

Ocean surface films can damp short capillary-gravity waves, reduce the surface mean square slope, and induce “sigma0 blooms” in satellite altimeter data. No study has ascertained the effect of such film on altimeter measurements due to lack of film data. The availability of Environmental Response Management Application (ERMA) oil cover, daily oil spill extent and thickness data acquired during the Deepwater Horizon (DWH) oil spill accident provides a unique opportunity to evaluate the impact of surface film on altimeter data. In this study, the Jason-1/2 passes nearest to the DWH platform are analyzed to understand the waveform distortion caused by the spill as well as the variation of σ0 as a function of oil thickness, wind speed and radar band. Jason-1/2 Ku-band σ0 increased by 10 dB at low wind speed (<3 m.s-1) in the oil-covered area. The mean σ0 in Ku and C bands increased by 1.0 - 3.5 dB for thick oil and 0.9 - 2.9 dB for thin oil while the waveforms are strongly distorted. As the wind increases up to 6 m.s-1, the mean σ0 bloom and waveform distortion in both Ku and C bands weakened for both thick and thin oil. When wind exceeds 6 m.s-1, only does the σ0 in Ku band slightly increase by 0.2 - 0.5 dB for thick oil. The study shows that high-resolution altimeter data can certainly help better evaluate the thickness of oil spill, particularly at low wind speeds.

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