New submodel for emissions from Explosive Volcanic ERuptions (EVER v1.1) within the Modular Earth Submodel System (MESSy, version 2.55.1)

Abstract. We present a methodological study to document the operation of a new submodel for tracer emissions from Explosive Volcanic ERuptions (EVER v1.1), developed within the Modular Earth Submodel System (MESSy, version 2.55.1). EVER calculates additional tendencies of gaseous and aerosol tracers based on volcanic emission source parameters, aligned to specific sequences of volcanic eruptions. It allows for the mapping of size-resolved volcanic ash to number and mass of different size modes, and the employment of various vertical emission profiles. The new submodel is evaluated in atmospheric simulations with the ECHAM/MESSy Atmospheric Model (EMAC) coupling the general circulation model ECHAM5 to EVER and other MESSy submodels, using satellite observations of SO₂ column amounts and mixing ratios as well as aerosol optical properties following the explosive eruption of the Nabro volcano (Eritrea) in 2011. Sensitivity studies explore perturbations of the emission source parameters, such as plume location, emitted mass, plume altitude, vertical distribution, and timing of the emission. We integrate information from a volcanic SO₂ emission inventory, additional satellite observations, and our findings from the sensitivity studies to establish a historical standard setup for volcanic eruptions impacting stratospheric SO₂ from 1990 to 2023. We advocate for this to be a standardized setup in all simulations within the MESSy framework concentrating on the upper troposphere and stratosphere in this period. Additionally, we demonstrate the applicability of the new submodel for the simulation of degassing volcanoes, with further potential applications in studies on volcanic ash, wildfires, solar geoengineering, and atmospheric transport processes.