| 06 Feb 2026
Evaluating SCIAMACHY-retrieved and ECHAM-simulated stratospheric aerosol characteristics by their comparison after volcanic eruptions
Abstract. Satellite observations and global aerosol–micropysical model simulations are essential to study the impact of volcanic aerosols on stratospheric composition and dynamics. However, despite their continuous improvements, uncertainties remain in satellite retrievals and model outputs due to assumptions about aerosol size, composition, and simplified model parameterizations. The SCIAMACHY v2.0 PSD algorithm for obtaining stratospheric aerosol characteristics assumes a fixed particle number density profile representative of background conditions. MAECHAM5-HAM simulations employ parameterized aerosol microphysics and chemistry. Both approaches might be affected by increased uncertainties after volcanically perturbed situations. We compare SCIAMACHY v2.0 PSD aerosol extinction coefficient and effective radius profiles with MAECHAM5-HAM simulations following the Manam (2004/2005) and Sarychev (2009) eruptions to evaluate both data products. SCIAMACHY retrievals and MAECHAM5-HAM simulations show strong consistency for the Sarychev eruption in plume location, particle growth within the plume, and size reduction at plume boarder. In contrast, SCIAMACHY observes the Manam plume further north, with differences in aerosol size evolution compared to MAECHAM5-HAM simulations. Additional comparisons with SAGE II and alternative SCIAMACHY retrievals after the Manam eruption confirm that the v2.0 PSD approach provides the most realistic aerosol characteristics from SCIAMACHY. A model parameter study highlights the importance of accurate background aerosol size information, its parameterization, and vertical injection profiles for realistic simulations of volcanic plumes. Nudging MAECHAM5-HAM with ERA5 reanalyis data improves the simulated atmospheric dynamics and brings the simulation output closer to observations. Increasing the horizontal injection area compensates for under-represented chemical interactions involving OH and volcanic ash. These findings provide valuable insights for improving the simulations of volcanic eruptions with aerosol-microphysical models and enhancing the interpretation of satellite-based aerosol data.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Measurement Techniques.
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