Initial conditions control transport of volcanic volatiles, forcing and impacts

Abstract

Abstract. Volcanic eruptions impact the climate and environment. The volcanic forcing is determined by eruption source parameters, including mass and composition of volcanic volatiles, eruption season, eruption latitude and injection altitude. Moreover, initial conditions of the climate system play an important role in shaping the volcanic response. However, our understanding of the combination of these factors, the distinctions between tropical and extratropical volcanic eruptions and the co–injection of sulfur and halogens remains limited. Here, we perform ensemble simulations of volcanic eruptions at 15° N and 64° N in January, injecting 17 Mt of SO2 together with HCl and HBr at 24 km altitude, considering different initial conditions of the El Niño–Southern Oscillation, Quasi–Biennial Oscillation, and polar vortex. Our findings reveal that initial conditions control the transport of volcanic volatiles from the rst month and modulate the subsequent latitudinal distribution of sulfate aerosols and halogens. This results in different volcanic forcing, surface temperature and ozone responses over the globe and Northern Hemisphere Extratropics (NHET) among the model ensemble members with different initial conditions. NH extratropical eruptions exhibit a larger NHET mean volcanic forcing, surface cooling and ozone depletion compared to tropical eruptions. However, tropical eruptions lead to more prolonged impacts compared to NH extratropical eruptions, both globally and in the NHET. The sensitivity of volcanic forcing to varying eruption source parameters and model dependency is discussed, emphasizing the need for future multi–model studies to consider the influence of initial conditions and eruption source parameters on volcanic forcing and subsequent impacts.