National Aeronautics and Space Administration

Abstract. Volcanic clouds can be uniquely discriminated from weather clouds with the total ozone mapping spectrometer (TOMS) instrument on the Nimbus-7 and Meteor-3 satellites. Sulfur dioxide, which is carried along with water and ash in volcanic eruptions, is measured by TOMS as a byproduct of ozone mapping. Eruptions are easily detected in sulfur dioxide maps because the background SO2 amounts are relatively small and uniform, whereas visible and infrared satellite images must be searched manually for distinctive cloud shapes. The TOMS technique also produces a quantitative estimate of eruption size based on sulfur dioxide content. Sulfur dioxide data from polar-orbiting satellites, couple with a short-term trajectory forecast, can be used to prepare volcanic aviation-hazard maps. The detection and tracking capability of TOMS is illustrated with examples from the June 1991 Pinatubo and May 1980 Mount St. Helens eruptions. The 50 volcanic eruption clouds detected with TOMS since 1978 include: Pinatubo, Mount St. Helens, El Chichon, Cerro Hudson, Alaid, Nyamuragira, Galunggung, Una Una, Ruiz, Redoubt, Hekla, and several Galapagos volcanoes.