## 1 Introduction  
The recent 2019-2020 bushfire season was one of the worst fire seasons ever recorded in Australia. Human death tolls were less than the previous Black Saturday bushfires in early 2009, where 173 people died; in fact, in the 2019-2020 bushfires, 34 confirmed deaths were recorded. The fires, nonetheless, had devastating immediate effects on the environment and the economy. Over 5900 buildings were destroyed and many billions of dollars of property were damaged across a vast area, with estimates ranging from 24.3 million hectares to 33.8 million hectares, making it the most costly and damaging bushfire season on record [1, 2]. Environmentally, over one billion mammals, birds and reptiles were killed and a further estimated 2 billion were displaced. In fact, the World Wildlife Fund puts estimates of deaths of animals at nearly 3 billion [3]. It has been suggested that entire species may have become extinct because of these fires [4], and many threatened species are now facing extinction [5, 6, 7]. These are the readily measurable and observable effects of bushfires.  
Climate change [8] predictions anticipate increases both in the number and intensity of bushfires in the future. It is widely known the overall effect of CO\({}_{2}\) on the warming of our climate but there is also evidence that aerosols from fires can also have an effect on the ozone layer. The two reports [9; 10], alongside many other papers, present the evidence for this. Accordingly, it is of vital importance to understand the relationship between bushfires-induced emissions of aerosol and other pollutants they release into the atmosphere on the one hand, and ozone depletion on the other. As illustrated in Figure 1 visible light is essentially unaffected by the ozone layer, whereas with harmful UV light the ozone layer scatters and absorbs it, significantly reducing the amount that reaches the surface.  
There are other, less easily observed effects. In particular, fires are a major source of pollutants originating from the land; specifically, particulate matter in the form of aerosols and greenhouse gases (mainly CO2) released into the atmosphere after the combustion of organic materials, i.e., plants. This plant matter is called biomass and when burned it releases aerosols [11].  
An image illustrating that aerosols are composed of a highly diverse mixture of particles ranging in size from individual tiny particles no more than 10 nm in diameter to large clustering aggregates containing hundreds of particles up to 2 um wide, is displayed in Figure 2.  
The aim of this study is to understand and quantify the spatiotemporal relationship between bushfires and ozone levels in the atmosphere. To this end we undertake statistical analysis, using modern empirical and spatiotemporal statistical techniques of bushfire and ozone layer data to discover and measure correlations both geographically and over time between the ozone and bushfire-induced aerosol datasets. We aim to analytically study and provide evidence for or against the hypothesis that bushfires result in a localized effect on the ozone layer in the vicinity of the bushfire or downwind of it.  
Figure 1: **(left)** NASA measurements of aerosols optical thickness over April 2019. **(right)** NASA measurements of aerosols’ optical thickness over December 2020.  
Figure 2: **(A)** Ammonium sulfate particles containing soot (marked by the small arrows) and fly-ash spheres (marked by the bold arrow in the lower-right corner). **(B)** In a typical branching soot aggregate; the arrows point to a carbon film that connects individual spherules within the aggregate. **(C)** Fly-ash spheres. Source: [12].