Breaking Boundaries: Using lasers to detect volcanic ash in the sky
Research at the University of Exeter helped avoid closure of UK airspace on two separate occasions in 2017 and 2019.
Volcanic ash is a hazard to aviation as it melts at the high temperature of aircraft turbines and crystalizes as it cools, jamming aircraft engines. Hence, UK airspace was closed subsequent to the eruption of the Icelandic volcano Eyjafjallajökull in 2010 which caused an extensive plume of ash across much of the North Atlantic and Europe. Flights were cancelled for many weeks with costs to the airlines of around 1.7 billion US Dollars and knock-on impacts on the global economy estimated at 4.7 billion US Dollars.
In response to this event, Professor Jim Haywood and his research team developed new aircraft and ground-based measurement capabilities to detect the location and concentrations of volcanic ash in the skies. Prof Jim Haywood and Martin Osborne also developed laser-scanning technology (lidar) to scan the air for volcanic ash. Crucially, they developed hardware, software and algorithms to improve the accuracy of volcanic ash concentrations and to discriminate non-spherical ash particles and absorbing smoke from other ‘background’ atmospheric aerosols. They used lidar combined with multi-wavelength scattered light measurements to enable volcanic ash concentrations to be detected down to 400 times less than the ‘no-fly’ limits adopted by the Volcanic Ash Advisory Centre and Civil Aviation Authority. This sensitivity is unrivalled in any global lidar network.
In 2017, 32 emergency procedure and MAYDAY calls from aircraft were received in UK airspace.
Saharan dust mixed with unusually high concentrations of atmospheric smoke originating from Portuguese wildfires was blown over UK airspace leading to smoke being smelt on aircraft – a serious and highly concerning event on any operational aircraft. Using Osborne and Haywood’s algorithms together with emergency dispersion simulations the National Air Traffic Services prevented more widespread disruption to the aviation fleet. If disruption to 1 in 10 flights was avoided, then the system will have saved the economy approximately £50 million.
In June 2019, Raikoke, an uninhabited volcanic island in the northwest Pacific Ocean erupted spewing ash high into the atmosphere.
The team used the same lidar system to detect volcanic ash in UK airspace at aircraft cruise altitudes from this eruption. On occasion, the concentrations of volcanic ash was higher than that detected during the period when airspace was closed due to the Eyjafjallajökull eruption in 2010 and volcanic ash continued to be detected for a period of around 3 weeks.
Whilst International Civil Aviation Organization regulations would have closed airspace in the UK previous to this research, the belief in the new detection algorithm meant flights could continue and hundreds of millions of pounds were saved by not restricting air travel.
Breaking boundaries provides a bitesize look into the variety of leading research that has, and still is changing the world from the University of Exeter.
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