• IASI;
  • Kasatochi;
  • hydrogen sulfide;
  • infrared;
  • remote sensing

[1] For the first time, satellite measurements have been made of hydrogen sulfide (H2S) in a volcanic plume. Volcanoes release H2S in large quantities—yearly global estimates range from 1 to 37 teragrams. Along with sulfur dioxide (SO2), which is estimated to be emitted from volcanoes at about 15–21 teragrams per year, H2S is a major portion of the volcanic sulfur released into the atmosphere. The ratio of H2S to SO2 emissions is useful for studying source conditions, sulfur chemistry, and magma-water interactions. However, unlike SO2, H2S has been challenging to measure in the atmosphere. Clarisse et al. used infrared satellite observations to characterize H2S from the 7–8 August 2008 eruption of the Kasatochi volcano in the Aleutian Islands. The eruption consisted of five explosive events; the observations indicated that the H2S plume was likely associated with the earlier events. The study shows that volcanoes are significant sources of H2S in the atmosphere and demonstrates for the first time that satellites can observe H2S plumes. (Geophysical Research Letters, doi:10.1029/2011GL047402, 2011)