Stratospheric ozone depletion inside the volcanic plume shortly after the 2022 Hunga Tonga eruption

This work analyzes the dynamic and chemical causes of this ozone depletion. The results show that the large water injection (similar to 150 Tg) from the HTHH eruption, with similar to 0.0013 Tg injection of ClO (or similar to 0.0009 Tg of HCl), causes ozone loss due to strongly enhanced HOx and ClOx cycles and their interactions.

Aside from the gas-phase chemistry, the heterogeneous reaction rate for HOCl + HCl -> Cl2 + H2O increases to 104 cm-3 s-1 and is a major cause of chlorine activation, making this event unique compared with the springtime polar ozone depletion where HCl + ClONO2 is more important. The large water injection causes relative humidity over ice to increase to 70 %-100 %, decreases the H2SO4 / H2O binary solution weight percent to 35 % compared with the 70 % ambient value, and decreases the plume temperature by 2-6 K. These changes lead to high heterogeneous reaction rates.