The chemical and emission footprint of nitrogen deposition in biodiversity hotspots

Atmospheric reactive nitrogen and ozone are two important atmospheric chemical inputs that have been associated with changes in ecosystem health and biodiversity. Anthropogenic activities have profoundly altered the atmospheric budget of both species, thus there is a clear need to apportion natural and anthropogenic sources such that effective targeted measures can be implemented. Deposition of these species is controlled by many complex processes including emissions, transport and photochemistry, but the relative importance of each process is not well known. Improving our understanding of the role of each will allow us to target appropriate laboratory experiments to ultimately create better model parameterizations. An adjoint model provides an efficient platform to calculate the sensitivity of one quantity (nitrogen or ozone deposition in this case) to many parameters. Here, we demonstrate the advantage of this technique to determine how the interplay between emissions and chemistry controls ozone and nitrogen deposition in various biodiversity hotspots, i.e. regions that exhibit unusually large richness in flora and fauna.