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Reconstruction of atmosphere-ocean circulation patterns for geological time slices by self consistent coupled model simulations

Recom is a project in a DFG Priority Program SPP 1375: "South Atlantic Margin Processes and Links with onshore Evolution" (SAMPLE).

In this project the evolutions of the three-dimensional atmospheric and oceanic circulation patterns from the early Cretaceous to a pre-industrial period are analysed. For this purpose, the climates of the Albian (110 million years ago, Ma), Cenomanian-Turonian Boundary (93 Ma), early Eocene (55 Ma), Pliocene (3.5 Ma) and a pre-industrial period (1850 AD) are simulated with a coupled atmosphere and ocean general circulation model. The progressive opening of the South Atlantic over the last 130 million years and the ensuing modification of the oceanic throughflows redirects the global ocean conveyor belt on geological time-scales. The simulations show that this significantly alters the transports of sediments close to the ocean bottom. In the early Eocene, for instance, the near-bottom velocities were reduced by more than 50% in comparison to the pre-industrial period. This led to a reduction of the oceanic sediment transport.

In addition, in this project the oceanic tides of the aforementioned time-slices are reconstructed and the influence of the tidally induced transports and ocean mixing on the atmosphere and the ocean are investigated. In the pre-industrial period, tides influence primarily sea ice dynamics and reduce sea ice concentration in the Weddell Sea by up to 30%. This alters the heat transfer between ocean and atmosphere which increases near surface atmospheric temperatures in the Weddell Sea by up to 4°C.


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