hide
Free keywords:
-
Abstract:
To enhance the understanding of our Earth system numerical experiments are performed contrasting a retrograde and prograde rotating Earth using the Max Planck Institute Earth System Model. The experiments show that the sense of rotation has relatively little impact on the globally and zonally averaged energy budgets, but leads to large shifts in continental climates, patterns of precipitation, and the structure of the ocean overturning circulation.
Most changes in the continental climate are expected, given ideas developed more than a hundred years ago: A general switch in the nature of the Euro-African climate with that of the Americas due to the reversal of the wind systems and the associated changes in storm tracks. However, the shift of storm track activity from the oceans to the land in the Northern hemisphere is surprising. Different patterns of storms influence fresh water transport, which may underpin the change of the role of the North Atlantic and the Pacific in terms of deep water formation, overturning and northward oceanic heat transport. These changes greatly influence northern hemispheric climate and atmospheric heat transport by eddies in ways that appear energetically consistent with a southward shift of the zonally and annually averaged tropical rain bands. Differences between the zonally averaged energy budget and the rain band shifts leave the door open, however, for an important role for stationary eddies in determining the position of tropical rains. Changes in ocean biogeochemistry largely follow shifts in ocean circulation, but the emergence of a "super" oxygen minimum zone in the Indian Ocean is surprising. The upwelling of phosphate enriched and nitrate depleted water provoke a dominance of cyanobacteria over bulk phytoplankton over vast areas, a phenomenon not observed in the prograde model.
