Evolution of the stratospheric aerosol enhancement following the eruptions of Okmok and Kasatochi: Odin-OSIRIS measurements

Limb-scattered sunlight measurements made by the OSIRIS instrument on the Odin spacecraft during the months following the eruptions of Mount Okmok and Kasatochi volcanos in 2008 are used to retrieve vertical profiles of the stratospheric aerosol extinction. These measurements reveal the evolution of the formation, transport, and decay of the stratospheric aerosol cloud that forms as a result of the volcanic eruptions. The maximum vertical optical depth of the stratospheric aerosol, measured by OSIRIS at 750 nm, occurs at midlatitude to high latitude 4 to 6 weeks after the Kasatochi eruption and is approximately a factor of 2 above the background level. Significant meridional transport in the lower stratosphere is evident in the observations, with measurable enhancement extending up to 21 km altitude and reaching tropical latitudes. Seven months following the eruption of Kasatochi, the stratospheric aerosol optical depth is very near the background level measured before the eruptions.