Forced and Free Meridional Circulations in the Atmosphere

Kuo, H. L.

doi:10.1175/1520-0469(1956)013<0561:fafmci>2.0.co;2

Cited by 95 publications

(39 citation statements)

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“…To analyze the mean meridional circulation we make use of the so-called Kuo-Eliassen equation (Kuo, 1956;Eliassen, 1951). This is a diagnostic equation which relates the mean meridional circulation (i.e., Hadley, Ferrel and Polar cell) to different sources.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…Our overall goal is to understand how the atmospheric energy transport and transformations are affected by modulations in the oceanic transport. We analyze the changes in the atmospheric heat transport and the mean meridional circulation by employing, amongst others, the Kuo-Eliassen equation (Kuo, 1956;Eliassen, 1951) in order to understand the various drivers of the mean meridional circulation.…”

Section: Introductionmentioning

confidence: 99%

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The impact of oceanic heat transport on the atmospheric circulation

Knietzsch¹,

Schröder²,

Lucarini

et al. 2015

Earth Syst. Dynam.

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Abstract.A general circulation model of intermediate complexity with an idealized Earth-like aquaplanet setup is used to study the impact of changes in the oceanic heat transport on the global atmospheric circulation. Focus is on the atmospheric mean meridional circulation and global thermodynamic properties.The atmosphere counterbalances to a large extent the imposed changes in the oceanic heat transport, but, nonetheless, significant modifications to the atmospheric general circulation are found. Increasing the strength of the oceanic heat transport up to 2.5 PW leads to an increase in the global mean near-surface temperature and to a decrease in its equator-to-pole gradient. For stronger transports, the gradient is reduced further, but the global mean remains approximately constant. This is linked to a cooling and a reversal of the temperature gradient in the tropics.Additionally, a stronger oceanic heat transport leads to a decline in the intensity and a poleward shift of the maxima of both the Hadley and Ferrel cells. Changes in zonal mean diabatic heating and friction impact the properties of the Hadley cell, while the behavior of the Ferrel cell is mostly controlled by friction.The efficiency of the climate machine, the intensity of the Lorenz energy cycle and the material entropy production of the system decline with increased oceanic heat transport. This suggests that the climate system becomes less efficient and turns into a state of reduced entropy production as the enhanced oceanic transport performs a stronger large-scale mixing between geophysical fluids with different temperatures, thus reducing the available energy in the climate system and bringing it closer to a state of thermal equilibrium.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The impact of oceanic heat transport on the atmospheric circulation

Knietzsch¹,

Schröder²,

Lucarini

et al. 2015

Earth Syst. Dynam.

View full text Add to dashboard Cite

show abstract

“…10. The zonally averaged circulation exhibits a weakening of the Northern Hemispheric jet stream, in particular at its southern flank, with implications for the global stationary and transient eddy momentum transport as well as for the meridional vertical circulation (Kuo 1956). The weakening of the Northern and Southern Hemispheric zonal mean jet streams by about 10% can be traced back to the domi- nance of the topographic forcing during LGM, as shown in Fig.…”

Section: A Feedback 1: Thermal Wind Changesmentioning

confidence: 99%

Synoptic Reorganization of Atmospheric Flow during the Last Glacial Maximum*

et al. 2005

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A coupled global atmosphere-ocean model of intermediate complexity is used to study the influence of glacial boundary conditions on the atmospheric circulation during the Last Glacial Maximum in a systematical manner. A web of atmospheric interactions is disentangled, which involves changes in the meridional temperature gradient and an associated modulation of the atmospheric baroclinicity. This in turn drives anomalous transient eddy momentum fluxes that feed back onto the zonal mean circulation. Moreover, the modified transient activity (weakened in the North Pacific and strengthened in the North Atlantic) leads to a meridional reorganization of the atmospheric heat transport, thereby feeding back onto the meridional temperature structure. Furthermore, positive barotropic conversion and baroclinic production rates over the Laurentide ice sheets and the far eastern North Pacific have the tendency to decelerate the westerlies, thereby feeding back to the stationary wave changes triggered by orographic forcing.

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“…Kuo, 1956;Charney and Drazin, 1961;Wallace and Holton, 1968). where it is required by (6-5) that the mean wind and temperature shall always remain in thermal wind balance.…”

Section: Frequency and Growth Rate Diagrammentioning

confidence: 99%

A Theory of Large-Scale Equatorial Waves Generated by Condensation Heat and Accelerating

Hayashi

1970

Journal of the Meteorological Society of Japan

174

156

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For the purpose of extending the theoretical interpretation of the large-scale equatorial waves discovered by Yanai and Maruyama (1966), a three-dimensional linearized primitive equation model of unstable waves is constructed on an equatorial beta plane.It is assumed that the release of latent heat due to moist convection in the troposphere is disturbed in proportion to the horizontal convergence in the subcloud layer responding to large-scale equatorial waves.It is found that Mode HB in the theory of unstable low latitude disturbances by Yamasaki (1969) is characterized by complex equivalent depth which simulates many aspects of YanaiMaruyama waves. This mode is further classified into various meridional modes, following Matsuno (1966). When the heat in the upper troposphere exceeds a critical value, unstable waves of free internal mode come into existence. Their growth rate increases with increasing heat in the upper troposphere.With the exception of inertio-gravity waves and Kelvin waves, mixed Rossby-gravity waves are the most unstable. The period corresponding to the observed wavelength of 10,000 km coincides with the observed period of about 4 days. The e-folding time is of the order of 10 days which, however, decreases with increasing wavelength.The energy and momentum budgets are also examined in detail. It is shown that a nonlinear forcing by Rossby type waves results in easterly acceleration of the mean zonal wind in the lower stratosphere, while Kelvin waves accelerate a westerly flow.

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Forced and Free Meridional Circulations in the Atmosphere

Cited by 95 publications

References 0 publications

The impact of oceanic heat transport on the atmospheric circulation

The impact of oceanic heat transport on the atmospheric circulation

Synoptic Reorganization of Atmospheric Flow during the Last Glacial Maximum*

A Theory of Large-Scale Equatorial Waves Generated by Condensation Heat and Accelerating

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