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Paul S. Schopf and Max J. Suarez

sure gradients. The model thus predicts sea-surface temperature, thermocline displacement, sea-level and currents. The salient climatological features of the tropical Pacific circulation--the east-west surface temperature gradients, the sloping thermocline, the surface easterly flow and the equatorial undercurrentm can be captured in such a model. Entrainment at the base of the mixed layer is pa rametefized using a bulk turbulent kinetic,energy budget similar to that proposed by Kraus and

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Ka Ming W. Lau

heatand momentum. There is an abundance of literature on the correlations between various components of the tropicalatmospheric and oceanic circulation. From observational studies Kraus (1959) established the existenceof oscillations in the recipitation-evaporation cyclesof the trades. Positive correlations between SST andthe strength of the ITCZ in the central Pacific werefirst suggested by Bjerknes (1966, 1969, 1972). A recent study by Ramage (1977), however, indicatedthat such a direct

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Ka-Kit Tung and Jiansong Zhou

1. Introduction El Niño Southern Oscillation (ENSO) is a dominant mode of natural oscillation of the equatorial coupled atmosphere–ocean system in the Pacific Ocean. The question of whether the equatorial Pacific responds to radiative heating in a La Niña–like (cold ENSO) pattern or an El Niño–like (warm ENSO) pattern is under debate in the context of global warming (see Vecchi et al. 2008 ). It has been argued that because of the tight coupling of the atmospheric Walker circulation with the

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Yi Deng, Tae-Won Park, and Ming Cai

) indicates 90% level of statistical significance. Figure 2 shows the partial temperature anomalies due to the six thermodynamic and dynamical processes obtained through CFRAM. Along the equatorial Pacific basin, changes in oceanic circulation, turbulent heat fluxes, and heat storage are responsible for an area-averaged cooling of approximately 4.9 K in the west and a warming of approximately 5.2 K from the central to eastern Pacific basin, consistent with shallowing thermocline anomalies in the west

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Gareth P. Williams

AuGusx1978 GARETH P. WILLIAMS 1399Planetary Circulations: 1. Barotropic Representation of Jovian and Terrestrial Turbulence GARETH P. WILLIAMSGeophysical Fluid Dynamics Laboratory/NOAd, Princeton University, Princeton, NJ 08540(Manuscript received 2 December 1975, in final form 13 April 1978)ABSTRACT We seek the formative processes of the planetary circulations

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Martin S. Singh, Zhiming Kuang, and Yang Tian

based on the simple model of the wind-driven subtropical overturning circulation outlined in Klinger and Marotzke (2000) . Briefly, the ocean circulation is assumed to be composed of a single subtropical overturning cell in each hemisphere consisting of a poleward surface flow, a return flow along the thermocline, and an upwelling branch at the equator. The surface flow is given by the Ekman transport associated with the surface wind stress, and the interior return flow is assumed to be adiabatic

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De-Zheng Sun and Richard S. Lindzen

the extratropical troposphere, the relativevorticity (0 is one order of magnitude or more smallerthan the planetary vorticity. Therefore, to first-order approximation, the PV is simply -gf(OO/Op). This corresponds to the planetary-scale approximation (Pedlosky 1987). The same approximation has been madeby oceanographers in their studies of the large-scalestructure of the thermocline circulation (Luyten et al.1983; Marshall and Nurser 1991). This greatly simplifies the calculation as we will see

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Matthias Münnich, Mark A. Cane, and Stephen E. Zebiak

most important: the vertical temperature profilein the upper layers of the tropical ocean does not havea constant gradient. (It resembles Fig. 2 turned on itsside. This of course is not accidental.) Consequently,a given change in thermocline displacement has a variable effect on the sea surface temperature and henceon the atmospheric circulation, depending on how closethe thermocline--the region of maximum gradient-is to the surface. The nonlinear model exhibits a rich behavior, notably

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J. David Neelin and Fei-Fei Jin

are neglected, as indicatedby the numerical results of Part I. In numerical andnonlinear work, we use an analytic version of theHeaviside function, ~(w), to ensure that all bifurcations can be brought into normal form. Here, we simplyset ~F(v~) = 1 and neglect d,Z~/dwl ~. The currents in the surface layer have two components: u~= u~ + urn,' w'~ = ws' + w,~'with subscript m denoting the part due to the verticalmean currents above the thermocline and subscript sdenoting the part due

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Paul A. O’Gorman and Tapio Schneider

ocean. The lowermost layer of the weather-layer simulation then corresponds to the abyss, with Rayleigh friction near the lower boundary corresponding to bottom drag. The eddies cannot be completely confined to the thermocline since the abyss is nearly adiabatic, so that in the heat budget of the abyss the ageostrophic circulation must be balanced by eddy fluxes. However, the idea of a deep meridional cell extending to the region of significant bottom drag as a means to close the zonal momentum

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