Stratospheric Ozone Loss from Volcanic Eruptions

ended

The stratospheric ozone layer absorbs harmful UV irradiation, protecting life on Earth. Only small changes are needed for significant damage to human health and agriculture, making it essential to understand the chemistry behind ozone depletion. Most of the ozone depletion has been caused by man-made emissions of the CFCs and halons, which are now banned through the Montreal Protocol and its amendments. However, due to the long-lived nature of these species, full recovery of the ozone layer is still decades away. In a changing climate, stratospheric composition, temperature and dynamics may be significantly altered, changing the catalytic ozone depletion in the future. Furthermore, new concerns regarding the ozone layer have emerged, with explosive volcanic eruptions possibly causing the largest perturbation to the ozone layer in the future. In this project, I will use different methods to determine the impact of halogen injections into the stratosphere on the ozone layer, determining the kinetics of bromine-containing species using laboratory and quantum chemical methods and incorporating them into a global chemistry and climate model. The first two years, I will be at Harvard, where I will use different atmospheric models to investigate the stratospheric impact of volcanic eruptions for a variety of future climate scenarios. I will also be carrying out experiments using cavity enhanced absorption spectroscopy to determine the kinetics of an atmospheric reservoir species for reactive bromine in the atmosphere. In the last year of the project I will be at University of Copenhagen and carry out experiments with a cold matrix setup with Fourier transform infrared spectroscopy to investigate the reaction. Throughout the project, I will determine the mechanisms of halogen reactions at the molecular level using quantum chemical calculations. I will introduce the results from the kinetic experiments and quantum calculations into the models as they become available.