Large scale modeling of the transport, chemical transformation and mass budget of the sulfur emitted during the April 2007 eruption of Piton de la Fournaise

Abstract. In April 2007, the Piton de la Fournaise volcano (Réunion island) entered into its biggest eruption recorded in the last century. Due to the absence of a sensors network in the vicinity of the volcano, an estimation of degassing during the paroxysmal phase of the event has not been performed. Nevertheless, the SO₂ plume and aerosols have been observed by the OMI and CALIOP space sensors, respectively. The mesoscale chemical model MesoNH-C simulates the observed bulk mass of SO₂ and the general shape of the SO₂ plume spreading over the Indian Ocean. Moreover, an analysis of the SO₂ plume budget estimates a total SO₂ release of 230 kt, among of which 60 kt have been transformed into H₂SO₄. 27 kt of SO₂ and 21 kt of H₂SO₄ have been deposited at the surface by dry deposition. With this top down approach, the temporal evolution of the SO₂ emission has been estimated during the most active period of the eruption. The peak of degassing was estimated at 1800 kg s⁻¹ in the morning of 6~April. The temporal evolution of SO₂ emission presented here can also be used for local studies.