The PhD defense of Cornelius Quigley takes place on March 2-3

Cornelius Quigley will on Wednesday March 3rd at 12:15 PM publically defend his thesis for the PhD degree in Science. The title of his thesis is «Determination of the Dielectric Properties of Marine Surface Slicks Using Synthetic Aperture Radar».

The trial lecture on «Remote Sensing of Marine Surface Films» is held Tuesday March 2nd at 14:15 AM. The defense and trial lecture will be streamed.

The NORSE2019 exercise, which Cornelius was part of, is important for oil spill monitoring and organizations engaged in oil spill contingency and preparedness planning. Both photos are from Ralf Horn who as on the FSAR plane.

Over the course of the last three decades, Synthetic Aperture Radar (SAR) has proven itself to be an effective monitoring technology for marine applications. The clear benefits of using SAR as opposed to optical devices is that SAR is insensitive to cloud cover, lighting conditions and can also provide imagery to a high degree of resolution. Given these benefits, there is a large incentive to implement SAR as a primary detection mechanism for marine oil spills due to the fact that SAR is capable of reliably providing data on a semi-daily basis. With increasing levels of maritime traffic due to declines in Arctic multiyear sea ice as well as risks associated with oil and gas exploration in the Arctic, being able to derive important geophysical information on the state of an oil slick is important for the decision-making process of first responders and clean-up personnel.  

This thesis is concerned with attempting to determine the dielectric properties of oil slick using SAR. The dielectric constant is a proxy for the volumetric water/oil content within an oil slick. This is due to the fact that when pure crude oil is inserted to the marine environment, it becomes subjected to a host of processes collectively referred to as weathering. Throughout these processes, oil-in-water emulsions can form that alter the dielectric properties of an oil slick resulting in a substance that has a dielectric value between that of pure crude oil and pure sea water depending on the volume of sea water present within an emulsion. In this thesis, we first apply a two-scale theoretical backscattering model to quad-polarimetric Radarsat-2 data of verified oil slick acquired during oil-on-water exercises conducted in the North Sea between the years of 2011-2013, acquired under varying wind conditions and incidence angles.  

The results showed realistic values for the dielectric constant given auxiliary information on the state of the slicks. However, no in-situ information was available to verify the model. A unique set of data was then acquired during the NORSE2019 oil-on-water experiment by DLRs F-SAR instrument in full quad-polarimetric X-, S- and L-bands. This data set was used to verify the model approach used in this thesis as well as to investigate the time variability of the discharged slicks using a stability measure in conjunction with a novel polarimetric feature that exploits the multifrequency aspect of the data set. The work presented in this thesis sheds light on the on-going discussion on the use of SAR for marine slick characterization.

His supervisors are:

  • Professor Torbjørn Eltoft, Department of Physics and Technology, UiT (main supervisor)
  • Professor Camilla Brekke, Department of Physics and Technology, UiT
  • Senior Researcher Veronique Miegebielle, TOTAL

Members of the evaluation committee are:

  • Dr. Martin Gade, Institut für Meereskunde, University of Hamburg, Germany (1. Opponent)
  • Assistant Professor Brent Minchew, Department of Earth, Atmosphere and Planitary Sciences, Massachusetts Institute of Technology, USA (2. Opponent)
  • Professor Rune Graversen, Department of Physics and Technology, UiT (internal member and leader of the committee)

Leader of the public defense:
The leader of the public defense is Professor Arne O. Smalås, Dean, Faculty of Science and Technology, UiT.

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