Model simulations of stratospheric aerosols from volcanic eruptions and their radiative forcing

Abstract:

The chemistry-climate model EMAC is used for transient simulations of interactive tropospheric and stratospheric aerosol processes from 1998 to 2012. We are analyzing data sets from 2002 to 2012 of the MIPAS instrument (SO₂ profiles) and the GOMOS instrument (aerosol extinction) on the ENVISAT satellite. To reduce data gaps, we are also using other satellites like GOME2, OMI, TOMS and SAGE to expand the timeline back to 1998. To simulate the radiative and chemical aerosol impacts by volcanic eruptions in the model we used 5-day data means and 3D-data fields of SO₂ during the ENVISAT period, rather than monthly means and point sources. In the previous period only monthly 3D fields from SAGE were available. The combination of all data sets enables us to identify emissions of 250 volcanic eruptions (small and medium size). The model simulations suggest that desert dust sources contribute to light extinction in the UTLS region and stratospheric aerosol radiative forcing of in total up to 0.15 W/m².