On the Stratospheric Ozone Response to the Magnitude and Latitude of Volcanic Eruption

Through dynamic and chemical mechanisms, stratospheric volcanic aerosol injections like the 1991 Pinatubo eruption can have a significant influence on stratospheric ozone. We used the climate model (CESM1.2) to diagnose the relative contributions by the Brewer-Dobson circulation (BDC), heterogeneous and gas-phase chemistry on ozone tendency in various locations and magnitudes of volcanic eruption.

In tropical volcanic scenarios, the simulated total chemical tendency of the stratospheric ozone is positive at 20 mb while negative at 10 mb, showing a hemispherical symmetric distribution. However, hemispherical asymmetric ozone chemical tendency is obvious in extratropical volcanic scenarios, which can be attributed to the smaller SAD and faster NOx-induced ozone destruction in non-erupted hemisphere. We further separate ozone chemical tendency into gas-phase and heterogeneous chemistry and find that the ozone tendency driven by gas-phase chemistry can surpass the ozone tendency caused by heterogeneous chemistry when the injected SO₂ amount exceeds 2 Tg. We also emphasize the crucial role of the ozone tendency caused by accelerating BDC, which has the same magnitude but the opposite sign of the chemical tendency dipole. Interestingly, the ozone tendencies caused by BDC and gas-phase chemistry nearly offsets each other in tropical eruption scenarios. In contrast, however, for the extratropical scenarios, the simulated ozone tendencies caused by gas-phase chemistry become more than that due to BDC, showing a less effective offsetting effect. In extratropical less effective offsetting situation, both the smaller vertical ozone gradience (∇O₃) and greater vertical residual velocity (w^*) play a major role and have nearly equal contribution.