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Keeping a weather eye on volcanic activity

Fears of volcanic eruptions are often in the news and consequent ash clouds can result in the re-routing or grounding of flights. But what does the Met Office have to do with all of this?

Photo credit: Arni Sigurdsson. © Icelandic Met Office

The Met Office runs the UK's London Volcanic Ash Advisory Centre (VAAC) from its Exeter HQ.  It is an International Civil Aviation Organization (ICAO) designated centre, responsible for issuing advisories for volcanic eruptions originating in Iceland and the north-eastern corner of the North Atlantic.

Following the Icelandic eruptions in 2010, the volcanic ash cloud led to flights being grounded for days at a time, not just here in the UK but across Europe and further afield.  This had knock on effects on international airports around the globe and impacted travellers, the aviation industry, and the wider economy. According to the International Air Transport Association (Iata) the costs of the disruption to the global airline industry was over $1.7bn (£1.1bn).

Since then the Met Office has continued to work very closely with the Department for Transport (DfT) and the aviation industry to look at ways of further improving the detection and monitoring of volcanic ash clouds in the event of future eruptions.

Over the last 2 years, a network of ten new particle-sensing Light Detection and Ranging Systems (LiDARs) has been installed right across the UK from Lerwick down to Cambourne, including one mobile unit based in Central England, all funded by DfT.

The LiDARs, specifically designed to sense atmospheric particles, are operated by the Met Office and kept in a state of continuous readiness.  They work by probing the atmosphere using light from a pulsed laser source. Backscattered light from suspended aerosols is monitored continuously using a receiver (telescope) and then plotted every 15 minutes, ready for immediate analysis.  This provides a profile of the vertical distribution and characteristics of particles in the atmosphere.  During a volcanic event these new observations will be used by our scientists to extract estimates of volcanic ash concentration, as well as provide the VAAC forecasters with a continuous visual analysis of the location and extent of the volcanic ash cloud.

LiDAR

Each LiDAR is accompanied by a sun photometer, an electronic device that measures direct sunlight over a narrow range of wavelengths. The information it collects is used to support ongoing research into more accurate and timely estimates of particle concentration levels.

Top view of a sun photometer

Information from the new network supports improved forecasts on the dispersion of ash.  These forecasts enable decision-makers in the aviation sector to take action to ensure the safety of travellers, and minimize any potential disruption.

The information from the LiDAR network is used in conjunction with data from satellites and other ash detection capabilities such as the Met Office Civil Contingency Aircraft.  Together, the data is used to provide experts at the Met Office with the best possible picture of real-time ash distribution.  These forecasts are then employed by airlines, NATS and Civil Aviation Authority (CAA) to assess the situation and make decisions on flight routing.