Topography-enhanced Diapycnal Mixing Impacts Oceanic and Atmospheric Circulation

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Topography-enhanced Diapycnal Mixing Impacts
Oceanic and Atmospheric Circulation
T. Friedrich, A. Timmermann (IPRC) T. Decloet,
D.S. Luther (U. Hawaii) and A. Mouchet (U. Liege)
The incorporation of a topography-enhanced
diapycnal mixing scheme into the Earth system
Model LOVECLIM impacted the global oceanic and
atmospheric circulation, and even marine
biogeochemistry. The increased diapycnal mixing
weakens stratification and strengthens the deep
overturning cell and equatorial upwelling. This
leads to Southern Ocean surface warming and
significant low-latitude cooling. These changes
have a series of cascading effects on the
representation of the following the Walker
circulation, equatorial upwelling, westerly winds
in the Southern Hemisphere, water-mass ages,
ventilation, and the oxygen minimum zones. The
results show the importance of a realistic
parameterization of diapycnal mixing for
numerical modeling. Using a coupled model
approach made it possible to see crucial
feedbacks of mixing on different Earth system
components. The figure shows changes in
horizontal velocity in the deep ocean resulting
from inclusion of the new mixing scheme.