Investigating the role of diapycnal ocean mixing for glacial climate stability and sensitivity
Diapycnal mixing is a source of potential energy in the ocean and is therefore believed to limit the rate of overturning on centennial and longer timescales. For the present-day ocean, winds and dissipation of tidal energy drive the diapycnal mixing with approximately similar contributions. Both components are thought to be considerably different in a glacial climate: A stronger meridional temperature gradient in the atmosphere implies intensified winds, whereas the distribution and strength of tidal dissipation is very sensitive to the ocean topography. The latter was changed significantly by the lower sea level during glacial times.
A coupled earth system model of intermediate complexity with a realistic tidal model and the best available paleo-data sources will be used to provide an integrated perspective on whether the stability of the glacial ocean state was generally changed due to a different state of the background diffusivity field. Furthermore, the relative and combined contributions of an increased freshwater flux and the associated sea level change will be assessed for different freshwater impeded overturning regimes.