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Rui Xin Huang

effort has been devoted to developing theory of the wind-driven circulation, or, as it is sometimes called, the thermocline theory. However, it has taken many decades of research effort to develop wind-driven circulation models with more than one moving layer. Two approaches have been developed from the beginning. Robinson and Stommel (1959) proposed a thermocline theory in which diapycnal mixing was explicitly included. At the same time, Welander (1959) proposed a theory in which the fluid in

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Tomomichi Ogata, Shang-Ping Xie, Jian Lan, and Xiaotong Zheng

feedback causes a negative skew of SST variability in the SE-TIO. Because of weak climatological annual-mean zonal winds, the mean thermocline is flat along the equator in the tropical Indian Ocean (TIO). In the SE-TIO where the thermocline is deep, SST responds more strongly to the shoaling than deepening of the thermocline during the upwelling season. We demonstrate this asymmetry of thermocline feedback in an ocean general circulation model (GCM) forced with wind variability that is sinusoidal in

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Pierre Welander and Cho-Teng Liu

a possible thermocline regime with vanishing east-west temperaturegradient. The assodated meridional-vertical circulation is entirely wind-driven, produdng a deep thermalstructure at high latitudes, a thin equatorial thermodine, and a vertical thermal front at the latitude of vanishing Ekman downwelling. Some numerical examples are given.1. The zonally-symmetric regime We consider a rectangular ocean of uniform depth inthe ~-plane (boundaries at x=0,a; y=0,bi ~.=0,-H)forced by a wind stress

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A. V. Fedorov, R. C. Pacanowski, S. G. Philander, and G. Boccaletti

that the maintenance of the shallow thermocline depends mainly on the deep thermohaline circulation, which involves the sinking of cold, saline surface waters in certain high-latitude regions [for a review of various approaches see Veronis (1969) ]. Robinson and Stommel (1959) assumed that the tropical thermocline remains shallow despite the downward diffusion of heat because that diffusion is countered by the upward motion of cold water from below the thermocline. Subsequently, estimates of the

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Geoffrey K. Vallis

. Building on prior work by Colin de Verdiere (1988 , 1989) and Salmon (1986 , 1990) , Samelson and Vallis (1997a , b, henceforth SV) explored the circulation of a planetary geostrophic ocean model in a single basin, concentrating on the density structure of the upper ocean. Perhaps their most significant result was that there are two distinct dynamical regimes in the thermocline. On isopycnals that outcrop in the subtropical gyre the balance in the thermodynamic equation is essentially adiabatic

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Joseph Pedlosky and Paul Robbins

) A model of the ventilated thermocline consisting of three adiabatic layers surmounted by a mixed layer offinite thickness is presented. The mixed-layer depth and density increase continuously northward, and theseattributes of the mixed layer are specified. The effect of the mixed layer on the thermocline circulation isexplicitly calculated. The mixed-layer thickness and its variation play a significant role in shifting the trajectories of the streamlineswestward. The shadow zones enlarge more

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John Marshall and Timour Radko

1. Introduction Thermocline theory offers plausible explanations of the structure of midlatitude ocean gyres in linear vorticity and Sverdrup balance as reviewed, for example, in Rhines (1993) and Pedlosky (1996) . Theories of ocean currents in zonally unblocked geometries such as the Antarctic Circumpolar Current (ACC) are much less well developed, however. In the absence of meridional boundaries, Sverdrup balance no longer applies and it is much less obvious how a meridional circulation is

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F. L. Yin, I. Y. Fung, and C. K. Chu

the Atlantic Ocean: thermocline water, intermediate water, North Atlantic Deep Water (NADW),and Antarctic Bottom Water (AABW). For forcing corresponding to the current climate, warm water and coldwater circulation routes produced in the model agree with those inferred from observations, for example, southward-flowing NADW overriding northward-flowing AABW in the western boundary. The model shows that subtropical gyres intensify, and thermocline depths become shallow, when deep

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Rui Xin Huang

special values of parameters these two branches join smoothly and form a solution extendingcontinuously to high latitude. Thus, in terms of the climatological mean circulation the midocean thermoclineseems to have self-adjusted so as to avoid discontinuity in the western boundary region. In other words, theexternal parameters for the midocean thermocline have to satisfy some intrinsic constraints imposed by westernboundary currents.1. Introduction During the past ten years thermocline theory

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Lewis M. Rothstein, Rong-Hua Zhang, Antonio J. Busalacchi, and Dake Chen

1. Introduction Although the ocean circulations in the subtropics and Tropics have been investigated separately by many (e.g., Pedlosky 1990 ; Philander 1990 ), it was not until recently that their interactions have received significant attention ( Pedlosky 1991b ; McCreary and Yu 1992 ; McCreary and Lu 1994 ; Liu 1994 ; Liu et al. 1994 ; Lu and McCreary 1995 ; Pedlosky 1997 ). Subtropical/tropical water pathways are fundamentally defined by the basin-scale structure of the thermocline

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