Polar middle atmospheric ozone: short term impact by solar protons and long-term trends

Despite being a minor constituent in the Earth's atmosphere, ozone effectively absorbs most of the harmfull UV radiation from the Sun. This not only protects the life on Earth, but also makes ozone an important constituent to understand the energy budget of the atmosphere.

In this thesis, we study the impact solar proton events on middle atmospheric ozone above north and south pole and long-term trends in the Arctic ozone layer. The objective is to asses how well the current state-of-the-art climate model captures the impact on atmospheric ozone by solar proton events by comparing the model with satellite-based observations. We also investigate the Arctic ozone for evidence of recovery by analysing time-varying trends over 20-year periods in time series of ozone collected from balloon-borne ozone soundings.

We find that the current state-of-the-art climate model provides a realistic representation of the atmospheric ozone impact by solar proton events when compared with satellite-based observations. Thus we conclude that the climate model provides a conservative platform for long-term simulations of the space weather influences on climate. We also find that the level of Arctic ozone was increasing in years before 2017. However, in the years that follows, we find that the level of Arctic ozone has been declining. Therefore, we conclude that the Arctic ozone recovery is not yet detectable and we highlight the importance of continued monitoring until an eventual recovery is finally found.