Enhancing volcanic eruption simulations with the WRF-Chem v4.8

Abstract. Volcanic eruptions are one of the major natural hazards, exerting profound effects on the environment and climate. The emissions associated with such eruptions pose substantial risks to terrestrial systems and public health, particularly through the induction of acid rain and air pollution. Volcanic ash influences populations at distances reaching several thousand kilometers from the erupted volcano. Also, accurate forecasting of volcanic clouds is crucial for air traffic control. This study introduces enhancements to the simulation of volcanic eruptions and the transport of volcanic material using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 4.8. Improvements include the addition of wet and dry deposition of ash and sulfate, improved SO2 chemical transformation mechanisms, and corrections of the gravitational deposition of ash. Ash, sulfate, and SO2 mass balance analyses were conducted. Furthermore, we included the direct radiative effect of ash and sulfate aerosols. Additionally, we developed an open-source Python-written emission preprocessor called PrepEmisSources to facilitate and streamline the preparation of volcanic emissions. Accordingly, the model code was extended to simulate complex volcanic emission scenarios using the emissions file prepared using the PrepEmisSources tool. The results suggest that the enhanced WRF-Chem v4.8 code provides an accurate representation of volcanic ash, SO2, and sulfate dispersion, deposition, and SO2 chemical transformation. These improvements will aid in volcanic debris forecasting and will allow for the use of the model for assessments of volcanic aerosols on climate and for geoengineering problems, including modeling of stratospheric aerosol injection.