Investigating the role of diapycnal ocean mixing for glacial climate stability and sensitivity

Duration: 
2007 - 2009
Participants: 
Ben Marzeion (PI)
Kerim Hestnes Nisancioglu
Trond Dokken
Jeffery Scott
Abstract: 

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.

Funding Agency: 
Research Council of Norway
Funding Amount: 
€290 000

Related Publications

Marzeion, B.; Levermann, A.; Mignot, J. , 2010 , Sensitivity of North Atlantic subpolar gyre and overturning to stratification-dependent mixing: response to global warming , Clim Dyn , 34 , 661 - 668 , DOI: 10.1007/s00382-008-0521-4
marzeion_etal_10.pdf , BibTex , EndNote Tagged

Marzeion, B.; Levermann, A. , 2009 , Stratification-dependent mixing may increase sensitivity of a wind-driven Atlantic overturning to surface freshwater flux , Geophys. Res. Lett. , 36 , L20602 , DOI: 10.1029/2009GL039947
marzeion_levermann_09.pdf , BibTex , EndNote Tagged

Marzeion, B.; Levermann, A.; Mignot, J. , 2007 , The Role of Stratification-Dependent Mixing for the Stability of the Atlantic Overturning in a Global Climate Model* , J. Phys. Oceanogr. , 37 , 2672 - 2681 , DOI: 10.1175/2007JPO3641.1
marzeion_etal_07.pdf , BibTex , EndNote Tagged

Marzeion, B.; Drange, H. , 2006 , Diapycnal mixing in a conceptual model of the Atlantic Meridional Overturning Circulation , Deep Sea Research Part II: Topical Studies in Oceanography , 53 , 226 - 238 , DOI: 10.1016/j.dsr2.2005.08.022
marzeion_drange_06.pdf , BibTex , EndNote Tagged