The global ocean circulation on a retrograde rotating earth

Kamphuis, V.; Huisman, S. E.; Dijkstra, Henk A.

doi:10.5194/cp-7-487-2011

Cited by 3 publications

(3 citation statements)

References 26 publications

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“…A southward shift in the position of the annually and zonally averaged position of the rain bands is consistent with shifts in the zero line of the atmospheric energy transport (the ITCZ). The shift in this line is as would be anticipated by changes in the global climate, i.e., from a warming of the tropics or increased Northern Hemisphere baroclinicity (Kang et al, 2008;Bischoff and Schneider, 2014). The origin of these changes is, however, not clear as the magnitude and position of the rainband shifts do not agree quantitatively with changes in the energy flux near the Equator.…”

Section: Resultsmentioning

confidence: 80%

“…Changes in the mean energy budget could be expected to affect the zonal distribution of precipitation. Building on the ideas developed by Kang et al (2008Kang et al ( , 2009 and Frierson et al (2013), Bischoff and Schneider (2014) argue that an in- To calculate the transport, we use 2-hourly data of velocities, surface pressure, temperature, and specific humidity (Keith, 1995). The data are averaged over the last 100 years of the simulation.…”

Section: The Atmosphere Its Energy Budget and The Surface Climatementioning

confidence: 99%

“…Is -as some studies argue (Wallace et al, 1989;Philander et al, 1996) -the reason primarily related to zonal asymmetries in how continental boundaries align with prevailing wind systems? Or is its preference for the Northern Hemisphere a consequence of hemispheric asymmetries in the zonally averaged energy budget (Chiang et al, 2003;Kang et al, 2008)? Even if the hemispheric asymmetries in the heat budget are important, this raises the question as to their origin.…”

Section: Introductionmentioning

confidence: 99%

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The climate of a retrograde rotating Earth

et al. 2018

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Abstract. To enhance understanding of Earth's climate, 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 regions of deep water formation. Changes in the zonal asymmetries of the continental climates are expected given ideas developed more than a hundred years ago. Unexpected was, however, the switch in the character of the European–African climate with that of the Americas, with a drying of the former and a greening of the latter. Also unexpected was a shift in the storm track activity from the oceans to the land in the Northern Hemisphere. The different patterns of storms and changes in the direction of the trades 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 not expected. The upwelling of phosphate-enriched and nitrate-depleted water provokes a dominance of cyanobacteria over bulk phytoplankton over vast areas – a phenomenon not observed in the prograde model. What would the climate of Earth look like if it would rotate in the reversed (retrograde) direction? Which of the characteristic climate patterns in the ocean, atmosphere, or land that are observed in a present-day climate are the result of the direction of Earth's rotation? Is, for example, the structure of the oceanic meridional overturning circulation (MOC) a consequence of the interplay of basin location and rotation direction? In experiments with the Max Planck Institute Earth system model (MPI-ESM), we investigate the effects of a retrograde rotation in all aspects of the climate system. The expected consequences of a retrograde rotation are reversals of the zonal wind and ocean circulation patterns. These changes are associated with major shifts in the temperature and precipitation patterns. For example, the temperature gradient between Europe and eastern Siberia is reversed, and the Sahara greens, while large parts of the Americas become deserts. Interestingly, the Intertropical Convergence Zone (ITCZ) shifts southward and the modeled double ITCZ in the Pacific changes to a single ITCZ, a result of zonal asymmetries in the structure of the tropical circulation. One of the most prominent non-trivial effects of a retrograde rotation is a collapse of the Atlantic MOC, while a strong overturning cell emerges in the Pacific. This clearly shows that the position of the MOC is not controlled by the sizes of the basins or by mountain chains splitting the continents in unequal runoff basins but by the location of the basins relative to the dominant wind directions. As a consequence of the changes in the ocean circulation, a “super” oxygen minimum zone develops in the Indian Ocean leading to upwelling of phosphate-enriched and nitrate-depleted water. These conditions provoke a dominance of cyanobacteria over bulk phytoplankton over vast areas, a phenomenon not observed in the prograde model.

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Section: Resultsmentioning

confidence: 80%

Section: The Atmosphere Its Energy Budget and The Surface Climatementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The climate of a retrograde rotating Earth

et al. 2018

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Numerical evolution of the asymmetry in the compositionally inhomogeneous lower mantle driven by Earth’s rotation

2016

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Numerical model calculations have been carried out to study the effect of the centrifugal force on the compositionally dense material accumulated in the lowermost mantle. The deformation of an initial dense layer encircling the core was investigated systematically as a function of the density difference between the lower dense and the overlaying mantle, b and the angular velocity of the planet, X in a two-dimensional cylindrical shell domain. It was established that increasing b does not influence the magnitude of the deformation of the dense layer but decreases the velocity of the deformation. The relaxation time of the deformation is inversely proportional to b similarly to post-glacial rebound. On the other hand, increasing X enhances the magnitude of the deformation but does not affect the deformation relaxation time. The magnitude of the deformation is approximately proportional to X 2 . It was pointed out that for the present-day mantle parameters, b = 2-4 % and X = 7.3 9 10 -5 1/s the equatorial elevation of the dense layer is about 2 km which more than two orders of magnitude less than the height of the seismically observed large low shear velocity provinces beneath Africa and Pacific. During the Earth's history when the rotation of our planet was faster the influence of the centrifugal force was much more significant and the equatorial elevation of the dense layer might have reached even 100 km.

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Size Matters: Another Reason Why the Atlantic Is Saltier than the Pacific

Jones

Cessi

2017

Journal of Physical Oceanography

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The surface salinity in the North Atlantic controls the position of the sinking branch of the meridional overturning circulation (MOC); the North Atlantic has higher salinity, so deep-water formation occurs there rather than in the North Pacific. Here, it is shown that in a 3D primitive equation model of two basins of different widths connected by a reentrant channel, there is a preference for sinking in the narrow basin even under zonally uniform surface forcing. This preference is linked to the details of the velocity and salinity fields in the “sinking” basin. The southward western boundary current associated with the wind-driven subpolar gyre has higher velocity in the wide basin than in the narrow basin. It overwhelms the northward western boundary current associated with the MOC for wide-basin sinking, so freshwater is brought from the far north of the domain southward and forms a pool on the western boundary in the wide basin. The fresh pool suppresses local convection and spreads eastward, leading to low salinities in the north of the wide basin for wide-basin sinking. This pool of freshwater is much less prominent in the narrow basin for narrow-basin sinking, where the northward MOC western boundary current overcomes the southward western boundary current associated with the wind-driven subpolar gyre, bringing salty water from lower latitudes northward and enabling deep-water mass formation.

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The global ocean circulation on a retrograde rotating earth

Cited by 3 publications

References 26 publications

The climate of a retrograde rotating Earth

The climate of a retrograde rotating Earth

Numerical evolution of the asymmetry in the compositionally inhomogeneous lower mantle driven by Earth’s rotation

Size Matters: Another Reason Why the Atlantic Is Saltier than the Pacific

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