Impacts of oil spill on satellite altimetry measurements

Cheng Yongcun (Center for Coastal Physical Oceanography, Old Dominion University, United States)

CoAuthors

Jean Tournadre (Laboratoire d’Océanographie Physique et Spatiale, IFREMER, CNRS, Université de Bretagne Occidentale, Plouzané, France, France); Xiaofeng Li (GST, NOAA/NESDIS/STAR, College Park, Maryland, USA, United States); Qing Xu (College of Oceanography, Hohai University, Nanjing, China, China); Bertrand Chapron (Laboratoire d’Océanographie Physique et Spatiale, IFREMER, CNRS, Université de Bretagne Occidentale, Plouzané, France, France)

Event: 2017 Ocean Surface Topography Science Team Meeting

Session: Application development for Operations

Presentation type: Type Poster

An altimeter is a nadir-looking radar that emits short electromagnetic pulses. It measures the backscattered power by the sea surface as a function of time to construct the echo waveform from which the geophysical parameters are estimated. 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 Deepwater Horizon (DWH) oil spill event occurred on 20 April 2010. It was the largest accidental marine oil spill in the U.S. petroleum industry history. The leak was finally stopped on 15 July 2010. An extensive set of in-situ and satellite (Synthetic Aperture Radar (SAR) and radiometers) data have been collected, archived, and distributed.

The availability of Environmental Response Management Application (ERMA) oil cover, daily oil spill extent, and thickness data acquired during the 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 (<3m/s) 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, the mean σ0 bloom and waveform distortion in both Ku and C bands weakened for both thick and thin oil. When the wind exceeds 6 m/s, 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.

 

Poster show times:

RoomStart DateEnd Date
Concerto Ballroom Thu, Oct 26 2017,14:00 Thu, Oct 26 2017,18:00
Cheng Yongcun
Center for Coastal Physical Oceanography, Old Dominion University
United States
yccheng.en@gmail.com