Simulation of a Permian climate and analysis of atmospheric transport and mixing processes

• Main Author: Schneider, Steven
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Johannes Gutenberg-Universität Mainz 2019
• Subjects: ddc:550; Sea ice
• Online Access: https://openscience.ub.uni-mainz.de/handle/20.500.12030/3035; https://hdl.handle.net/20.500.12030/3035; https://doi.org/10.25358/openscience-3033

The modelling of palaeoclimates allows to analyse the environment of a certain period in the past. Additionally, it can give insight to the behaviour of specific atmospheric processes under altered circumstances. The Permian (299-251 mya) provides promising topographical and atmospheric conditions for palaeoclimate studies. The supercontinent of Pangaea predominated the topography which is one of the best known reconstructed topographies of the Palaeozoic and Mesozoic. Its extensive landmass comprised almost all of the present-day continents and stretched nearly from pole to pole. In the course of that period the atmospheric carbon dioxide content increased significantly to a multiple of the present-day concentration and induced global warming. The application of the established atmosphere-ocean general circulation model EMAC-MPIOM to simulate the palaeoclimate of the Middle Permian requires the estimation of boundary conditions, like e.g. the fraction of greenhouse gases and the astronomical setting, as well as the generation of a full land surface data set. The response stage of atmosphere and upper ocean layers to the changed conditions is in the magnitude of a few years, whereas it lasts several thousand years of simulation for deep ocean layers. The found equilibrium shows only a small net radiation imbalance and the equilibrium state turns out to be unique and independent of initialisation. The simulated mean climate for the Middle Permian is characterised by warm temperatures, especially in high latitudes, extreme saisonality and dry conditions in the continental interior. There is no permanent sea ice coverage on both hemispheres and the vicinity of the Tethys Ocean is subjected to a monsoonal climate. The geographic distribution pattern of associated biomes matches well the pattern derived from lithological and floral data in the Southern Hemisphere and in the low latitude range of the Northern Hemisphere. The higher resolution of the model results in warmer temperatures and increased precipitation in ...