Quantification of the impact of adjusted ozone climatology on a warmer than present climate simulated by AWI-ESM-2.1-LR

The existence of ozone as a greenhouse gas in the Earth‘s climate system has a great impact on the radiative transfer in the atmosphere, affecting among others, the global climate. Various climate modelling studies have highlighted the importance of ozone as a key driver of climate change. However, the climate models at the research group, Paleoclimate Dynamics at The Alfred Wegener Institute (AWI) lacked the interactive chemistry scheme for calculating ozone changes due to the enormous computational expenses. In this respect, this thesis addresses the vital question of the accuracy of specific climate patterns in the atmosphere-ocean coupled model AWI-ESM-2.1-LR, in comparison to the behaviour of a real climate state where ozone is fully forcing and reacting to climate changes. Quantification of the adjusted ozone in response to 4xCO2 is crucial, taking into account how modified ozone impacts the climate. In this study, the average values of surface temperature, total precipitation, vertically integrated water vapour, geopotential height at 500 hPa, 250 hPa, 100 hPa levels, and sea ice concentration together with the model metrics like climate sensitivity and polar amplification has been investigated under the aegis of Pre-Industrial (PI), 4xCO2, and 4xCO2_O3 simulations. These simulations have been performed by AWI-ESM-2.1-LR, a state-of-the-art climate model that will be used as a workhorse for simulating various climate states, from much warmer to present, to much colder than present climate states. Noteworthy is the intense Arctic warming during boreal winter in the 4xCO 2 simulation. This pronounced warming can be manifested by the strong increase in vertically integrated water vapour in the Northern Hemisphere (NH) high latitudes. However, the modified ozone forcing on the surface temperature response to 4xCO2 produces a cooling pattern. Furthermore, an enhanced precipitation pattern of 1069.72 mm/year is observed in the tropical mid-latitude region covering