Sulphur dioxide as a volcanic ash proxy during the April–May 2010 eruption of Eyjafjallajökull Volcano, Iceland

Abstract. The volcanic ash cloud from the eruption of Eyjafjallajökull volcano in April and May 2010 resulted in unprecedented disruption to air traffic in Western Europe causing significant financial losses and highlighting the importance of efficient volcanic cloud monitoring. The feasibility of using SO₂ as a tracer for the ash released during the eruption is investigated here through comparison of ash retrievals from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) with SO₂ measurements from a number of infrared and ultraviolet satellite-based sensors. Results demonstrate that the eruption can be divided into an initial ash-rich phase, a lower intensity middle phase and a final phase where considerably greater quantities both ash and SO₂ were released. Comparisons of ash-SO₂ dispersion indicate that despite frequent collocation of the two species, there are a number of instances throughout the eruption where separation is observed. This separation occurs vertically due to the more rapid settling rate of ash compared to SO₂, horizontally through wind shear and temporally through volcanological controls on eruption style. The potential for the two species to be dispersed independently has consequences in terms of aircraft hazard mitigation and highlights the importance of monitoring both species concurrently.