[1] Infrared spectra measured by the Atmospheric Chemistry Experiment Fourier

Transform Spectrometer (ACE-FTS) on the SCISAT satellite were used to analyze the Sarychev volcanic aerosol after the eruption in June 2009. Evidence of the Sarychev eruptions was first detected in July 2009 from enhanced SO2 concentrations and atmospheric extinction. By February 2010, the atmosphere had returned to pre-Sarychev conditions. In July 2009, the volcanic plume was found between 8.5 km and 17.5 km in altitude at mid- and high latitudes (55°N–70°N). The first SO2 and sulfate aerosol retrievals carried out using the infrared solar occultation spectra recorded with the ACE-FTS are presented here. The size distribution parameters, the aerosol volume slant column and the composition of the sulfate aerosol were obtained by using a least squares algorithm. The maximum volume slant column of the aerosols was found to be 850 mm3 cm3 km, which results in an approximate aerosol loading of 3 mm3 cm3. One month after the eruption, the composition of the aerosols providing the best-fit is a 75 % sulfuric acid-water solution with an effective radius (Reff) of 0.1–0.3 mm