Observations of the 2008 Kasatochi volcanic SO2 plume by CARIBIC aircraft DOAS and the GOME-2 satellite

摘要

The 2008 Kasatochi volcanic eruption emitted≈1.5–2.5 Tg SO into the upper troposphere and lowerstratosphere. Parts of the main volcanic plume (gases and particles) reachedcentral Europe a week after the eruption and were detected there by theCARIBIC (Civil Aircraft for Regular investigation of the Atmosphere based onan Instrument Container) flying observatory. The plume was also observed bythe GOME-2 satellite instrument, only a few hours after the CARIBICaircraft had crossed the plume, thus giving a unique opportunity to compareresults. Trajectories and local wind speeds are investigated in detail usingthe GOME-2 and CARIBIC observations for better comparison of theresults from these two observational systems. A comparison of the satellite spatialpattern with the local observations of the wind speed and the trajectorymodel TRAJKS showed a slight discrepancy, which has to be considered forsatellite validation. Hence, it appears that detailed analyses of wind speedsare required. Emitted and secondary particles, partly measured and sampled bythe CARIBIC in situ instruments, affected the DOAS SO measurements, ofboth CARIBIC and GOME-2. Overall GOME-2 and the CARIBIC SOmeasurements agree very well. The major uncertainties remain the actual windspeed needed to properly correct for the advection of the plume between thedifferent overpass times and effects of aerosols on DOAS retrievals. Thegood agreement can be seen as validation for both GOME-2 and CARIBIC DOASobservations.