HR: 0800h
AN: NS11A-0162    [Abstracts]
TI: Oil Detection In and Under Sea Ice Using Ground-Penetrating Radar
AU: * Steinbronn, L
EM: lsteinbronn@cgiss.boisestate.edu
AF: CGISS Boise State University, 1910 University Dr, Boise, 83725-1536,
AU: Bradford, J
EM: johnb@cgiss.boisestate.edu
AF: CGISS Boise State University, 1910 University Dr, Boise, 83725-1536,
AU: Liberty, L
EM: lml@cgiss.boisestate.edu
AF: CGISS Boise State University, 1910 University Dr, Boise, 83725-1536,
AU: Dickins, D
EM: dfdickins@sbcglobal.net
AF: DF Dickins Associates Ltd, 9463 Poole St, La Jolla, 92037,
AU: Brandvik, P J
EM: per.brandvik@sintef.no
AF: SINTEF, Brattørkaia 17 B, Trondheim, 7465, Norway
AB: Marine oil spills can occur in the Arctic due to pipeline breaks or leaks and spills from storage or production facilities. Depending on the time of year and scenario, a portion or all of the spill may become trapped under and/or encapsulated within the sea ice sheet. The current methods for locating spilled oil include visually inspecting drilled ice cores or sending divers under the ice. Speed is a key issue in oil clean-up. A non-invasive method of detecting oil quickly and reliably would greatly facilitate the clean-up and lessen the impact on the environment. First-year ice thicknesses of 0.5-2.0 m, typical of the Arctic region, can be well-resolved using radar. Oil film thicknesses can range from a few mm to 20 cm depending on the ice-water interface topography. For typical conditions a frequency of 500 MHz gives a 1/4 wavelength limit of 7 cm; therefore a typical spill scenario is a thin-bed problem for ground-penetrating radar (GPR). Interference due to thin-beds may cause amplitude, phase and frequency anomalies in the reflected wavelet. In April 2006, SINTEF conducted a contained oil-spill under natural Arctic sea ice conditions in a fjord on Svalbard. Using data collected during that experiment from a 500 MHz antenna and complex trace analysis we computed the instantaneous frequency, instantaneous phase and the envelope function and found significant differences in the data before and after the oil was inserted. These results demonstrated the potential of GPR to be a practical system for oil in ice detection under certain conditions. As a follow-on to the 2006 project, we have undertaken a detailed modeling effort to estimate GPR response to specific variables, such as ice and oil thicknesses, ice salinity and temperature.
DE: 0750 Sea ice (4540)
DE: 0792 Contaminants (0432)
DE: 0798 Modeling
DE: 4540 Ice mechanics and air/sea/ice exchange processes (0700, 0750, 0752, 0754)
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting