Atmospheric chemistry of an Antarctic volcanic plume

The observations were made in December 2005 both at source, with an infrared spectrometer sited on the crater rim, and up to 56 km downwind, using a Twin Otter aircraft; with the two different measurement platforms, plume ages were sampled ranging from <1 min to as long as 9 h. Three species (CO, carbonyl sulfide (OCS), and SO₂) were measured from both air and ground.

While CO and OCS were conserved in the plume, consistent with their long atmospheric lifetimes, the downwind measurements indicate a SO₂/CO ratio about 20% of that observed at the crater rim, suggesting rapid chemical conversion of SO₂. The aircraft measurements also identify volcanogenic H₂SO₄, HNO₃ and, recognized for the first time in a volcanic plume, HO₂NO₂. We did not find NOx in the downwind plume despite previous detection of NO₂ above the crater.