Here’s a magnified image of what’s been causing international travel chaos for days. It’s an image of silica particles from the Icelandic volcano Eyjafjallajökull, currently spewing out a huge ash cloud, which might now be abating. The picture was taken by Ian Russell, a public science promoter, using his home microscope. Russell scraped the ash from his car, which was parked on his drive in Derbyshire, UK.
As the airspace in northern Europe is slowly reopened, according to reports, airlines will be starting to breathe a short, shallow sigh of relief. They have been claiming that the grounding of flights for days now was unnecessary and it was safe to fly. Dutch airline KLM ran a test flight and KLM president & CEO, Peter Hartman declared “there is no reason to suspect that anything is amiss”.
But this is not a reason to start flying again says Fred Prata, Senior Scientist at the climate and atmosphere department of the Norwegian Institute for Air Research. Prata says that the grounding of flights is the right decision. The tests like that run by KLM, he says are “not very clever”. Prata says that to determine how damaging the ash is, the test must take place in the cloud, not just a random flight.
A Finnish fighter jet did fly into the ash cloud and the damage to its engines can be clearly seen. Last week the UK’s Natural Environment Research Council flew a plane to te edge of the cloud, and today the German Space Research Agency (DLR) is flying into the ash cloud to get more information about its make up and particle size. This information will help people like Prata who are scrambling to produce 3-D models of the ash cloud.
Prata, and others around the globe, are using satellite images, combined with dispersive models, to try and show what is happening. The models take into account wind shear, and the different directions the wind flows in different parts of the atmosphere. Each simulation is run many times until the answer matches the satellite observations. The parameters used in the correct simulation can then be used to forecast what the ash will do next. And data about particle size from the test flights into the ash cloud itself, even the microscope images of the particles taken by Russell, will make these simulations much easier to run, and much more accurate. These models are being used by the network of nine volcanic ash advisory centres (VAACs) around the world. At the moment the London VAAC has responsibility for providing predictions about the volcano ash, but as the ash moves this could shift to Toulouse, or even Washington DC.
The ash contains silica: it’s basically glass. The particles are so fine that pilots can’t see them, says Prata, but they can do huge amounts of damage to jet engines, also causing them to stall. Prata has been working on this problem for 20 years, and in a paper in Nature in 1991 proposed a simple ash detector that could be mounted in the cockpit of any plane. The concept was not developed by the air flight industry, Prata says, but if it had, planes would be flying today, and wouldn’t be grounded, because they would have the capability of being able to detect and avoid the ash hotspots, he predicts.
And will the ash have a lasting effect on our climate? Probably not according to Alan Robock, a meteorologist from Rutgers University, New Brunswick, US. “So far, the emissions have been so small, that I expect no climate impacts,” he says. On April 14, there was 0.004 megatons of sulphur dioxide, as compared to 20 megatons for Mount Pinatubo in 1991, and it was emitted into the troposphere, where its lifetime is only a week or so, as opposed to 1-2 years for the stratosphere for Pinatubo. The ash will also fall out quickly, so I expect no climate impact, unless the eruption gets much stronger.”
Image: Ian Russell