Simulating the Volcanic Sulfate Aerosols From the 1991 Eruption of Cerro Hudson and Their Impact on the 1991 Ozone Hole.

The Chilean volcano Cerro Hudson erupted between August 8th and 15th, 1991, injecting between 1.7 and 2.9 Tg of SO2 into the upper troposphere and lower stratosphere. We simulate this injection using the Goddard Earth Observing System Earth system model with detailed sulfur chemistry and sectional aerosol microphysics, focusing on the resulting aerosols and their contribution to the 1991 Antarctic Austral Springtime ozone hole. The simulations show a column ozone deficit (12 DU) in the Southern Hemisphere vortex collar region. The majority of this effect is between 10 and 20 km and due to heterogeneous chemistry. The model shows a 26% decrease in ozone from background levels at these altitudes, compared with in‐situ observations of a 50% decrease. Above 20 km, the dynamical response to the eruption also causes lower ozone values, a novel modeling result. This experiment highlights potential interactions between proposed solar radiation management geoengineering aerosols and volcanic eruptions. Plain Language Summary: We simulated the August 1991 eruption of Chilean volcano Cerro Hudson. Cerro Hudson erupted 2 months after the June 15th eruption of Pinatubo which was one of the largest observed eruptions. The combination of these two eruptions impacted the atmosphere by injecting volcanic aerosol which are well represented by our model. In the case of Cerro Hudson, the simulations show that the volcanic plume may have impacted the 1991 Antarctic ozone hole, both by directly impacting the chemistry of ozone depletion and by altering the dynamics of the atmosphere, slowing down the normal breakdown of the ozone hole caused by changes in weather. The interaction between Cerro Hudson and Pinatubo shown here also reveal a need for more research in how potential goengineering scenarios would interact with volcanic eruptions. Key Points: The August 1991 eruption of Cerro Hudson is simulated using a model with detailed aerosol microphysics and stratospheric chemistryThe model shows skill in simulating the satellite and in‐situ observations of the volcanic plumeThese simulations present a prima facie case that this eruption contributed to the anomalously high 1991 Austral Springtime ozone loss [ABSTRACT FROM AUTHOR]