For such scenarios, the most promising detection technology is ground-penetrating radar (GPR), which uses high-frequency radar signals, emitted either from a sled on the surface of the ice or from a low-flying aircraft, to provide an image of the subsurface.
As with other imaging technologies, the real improvements in GPR in recent years have been in the software for making sense of the collected data, rather than in hardware, says David Dickins, project manager of the SINTEF experiment.Even so, GPR has its limitations.
As with some GPR systems, NMR systems are carried by helicopter.
But the test also highlighted the limitations of GPR, particularly in conditions when the ice is close to melting.To get a more accurate picture of oil under the ice layer, several companies are working on detection systems based on nuclear magnetic resonance (NMR).
The situation is further complicated by the presence of salt, which absorbs the radar signals, weakening the reflection.Earlier this year America's Bureau of Safety and Environmental Enforcement, with support from ExxonMobil, Shell, Statoil and other oil giants, conducted an experiment with high-power radar to try to improve the range of conditions in which GPR would be effective.
But the large, ring-shaped antenna required is much larger than that required for GPR.
Instead, the authors of the new paper employ a technique called Gaussian process regression (GPR), which is not commonly used in the field of global health, but which they believe is more accurate, to plug the gaps and make the forecasts.Predictive modelling will never be as valuable as lots of boots on the ground collecting reliable data, of course.
Ridges, hollows, and variation in thickness can all deform or scatter the GPR signal, making the picture less clear and oil spills harder to spot.
A helicopter-mounted GPR system successfully differentiated between ice sheets that concealed oil and those that did not.
And proud as he is of GPR, Christopher Murray, the head of the IHME, acknowledges that it accounts for only a third of the explanation for his study's striking results.
The Pre-U diploma Three Pre-U subjects plus an individual research report and a global perspectives portfolio (GPR) qualifies a student for the Pre-U diploma.
