Research aircraft returns to volcanic ash plume

16 April 2010 by Tom Marshall

UK scientists are flying back to the predicted location of the ash plume coming from the Eyjafjallajökull volcano that is erupting in Iceland.

Satellite image of the ashplume from erupting volcano in Iceland

The plume is very dangerous to aircraft and has grounded flights across much of Europe. The researchers hope to pinpoint its location and find out how it is moving and changing shape.

This will help authorities decide when it will be safe for passenger aircraft to take to the air again. They will also gather valuable data that will let scientists improve models of how these plumes disperse into the atmosphere and affect local weather patterns. The images embedded in this article were prepared on April 15 from data received at the NERC-funded Satellite Receiving Station in Dundee; click on them to see a full-sized version.

The scientists are onboard NERC Airborne Research & Survey Facility's Dornier 228 research aircraft, based at Gloucester Airport. The aircraft had already flown to Cranfield Airport in Bedford to be fitted with the necessary equipment, which will tell researchers when they are nearing the plume so they can avoid flying through it and risking engine failure.

Satellite image of the ashplume from erupting volcano in Iceland

Satellite image of the erupting volcano in Iceland, taken by NASA's Aqua satellite at 13:29UTC.

"The technique we use is to fly towards the expected position of the plume while monitoring the instruments - highly-sensitive gas analysers and particle counters - to determine the point at which the concentrations of sulphur dioxide and volcanic ash start to increase," says Peter Purcell, head of NERC Airborne Research Facilities.

"This indicates that we are approaching the edge of the plume, and the aircraft can turn away before the contamination reaches an unacceptable level. The process is then repeated along the expected length of the plume, and the position of the edge can be plotted on a map," he adds.

The same team flew out to the plume's expected location on Thursday, but did not find the ash. Although this outcome was negative, this does necessarily mean the ash clouds are not dispersing as the models predict - further investigation is needed. After returning to refuel and replenish supplies, they are now going back to take further measurements. The Dornier took off on Friday afternoon; it can stay aloft for up to five hours, but may return sooner if the team get the information they need.

Satellite image of the ashplume from erupting volcano in Iceland

Satellite image of the erupting volcano in Iceland, taken by NASA's Terra satellite at 11:39UTC

The Dornier is normally used for low-altitude remote sensing of the land and atmosphere using instruments such as radar and lidar - the latter is like radar but uses lasers instead of radio waves to build up a picture of distant objects. Atmospheric sampling work like this mission is normally the job of another aircraft, the Facility for Airborne Atmospheric Measurement's (FAAM) BAe-146.

Based at Cranfield, this is bigger than the Dornier and equipped with a suite of extremely sensitive instruments for measuring the composition of the atmosphere. It is also much more comfortable at the high altitudes at which the ash plume is found, because of its pressurised hull. But it is undergoing maintenance, so the smaller aeroplane was quickly readied and brought to Cranfield to be outfitted with new instruments and pick up specialists to operate them, before flying north to where the ash plume is now thought to be.

FAAM is operated jointly by the NERC and the Met Office.