Bremen 2017 – wissenschaftliches Programm
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UP: Fachverband Umweltphysik
UP 2: Ozeanographie/Hydrosphäre
UP 2.2: Vortrag
Dienstag, 14. März 2017, 09:15–09:30, GW2 B3009
Oil spill detection by imaging radars: challenges and pitfalls — •Werner Alpers1, Ben Holt2, and Kan Zeng3 — 1Universitaet Hamburg, Institut fuer Meereskundede — 2NASA/JPL. Pasadena, CA, USA — 3Ocean University of China, Qingdao
Criteria for discriminating between radar signatures of oil films and biogenic slicks visible on synthetic aperture radar (SAR) images of the sea surface as dark patches are critically reviewed. We question the often claimed high success rate of oil spill detection algorithms using single- frequency, single-polarization SARs because the SAR images used to train these algorithms are based usually on subjective interpretation and are not validated by on-site inspections or multi-sensor measurements carried out from oil pollution surveillance planes. Furthermore, we doubt that polarimetric parameters derived from fully-polarimetric SAR data, like entropy, anisotropy, and mean scattering angle are beneficial for discriminating between mineral oil films and biogenic slicks. We conjecture that the results obtained from previous analyses of spaceborne polarimetric SAR data, which seem to show differences in the scattering mechanism between scattering from mineral oil films and biogenic slicks, result from instrument noise. Measurements carried out with the Unmanned Aerial Vehicle Synthetic Aperture Radar (UAVSAR) of NASA/JPL, which has an extremely low noise floor (-53 dB) , confirm this view and show that Bragg scattering theory applies also for scattering from mineral oil films.