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Radu Herbei, Ian W. McKeague, and Kevin G. Speer

1. Introduction Directly observed flow at the depths of the North Atlantic Deep Water in the South Atlantic Ocean shows a system of alternating zonal jets ( Hogg and Owens 1999 ). Deep zonal flow has been explained, for example, using a coarse wind-driven circulation model in the Pacific Ocean ( Nakano and Suginohara 2002 ). Several numerical models of varying resolution of the South Atlantic Ocean have been used to study the origin of the zonal flows, leading to the conclusion that wind is the

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Audrey Delpech, Claire Ménesguen, Yves Morel, Leif N. Thomas, Frédéric Marin, Sophie Cravatte, and Sylvie Le Gentil

1. Introduction The deep equatorial and tropical circulation is organized into systems of alternating eastward and westward jets ( Firing 1987 ; Firing et al. 1998 ; Johnson et al. 2002 ; Ollitrault et al. 2006 ; Ascani et al. 2010 ; Cravatte et al. 2012 ; Ollitrault and Colin de Verdière 2014 ; Qiu et al. 2013 ; Cravatte et al. 2017 ). We distinguish in particular (i) meridionally alternating off-equatorial jets with a meridional scale of ~3° within the 15°S–15°N latitude range, which

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Ivana Cerovečki, R. Alan Plumb, and William Heres

layer ( section 3 ). The role of eddies in maintaining the equilibrium state is discussed in section 4 within the framework of the TEM formalism. The residual circulation and residual fluxes of buoyancy and PV are weak in the near-adiabatic interior except in the vicinity of the main jet. “Eddy drag,” which represents eddy forcing in the momentum equation and can be represented as a function of residual PV flux along the mean isopycnals and the diapycnal buoyancy flux ( Plumb and Ferrari 2005

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Stephanie Waterman and Steven R. Jayne

free, inertial, unstable jets, characterized by large-amplitude meanders and pinched-off eddies. These WBC jets are of fundamental importance to the dynamics of steady basin-scale circulations as regions of enhanced exchange of potential vorticity (PV) and energy, and they act to restore global balances between forcing and dissipation. Understanding their dynamics is fundamental to improving our understanding of the ocean general circulation. Observations indicate that eddy kinetic energy (EKE) is

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Ryo Furue, Julian P. McCreary Jr., Zuojun Yu, and Dailin Wang

1. Introduction a. Observations The Pacific subsurface countercurrents (SCCs) are eastward jets located along thermal fronts at the poleward edges of thermostad water. They were first reported by Tsuchiya (1972 , 1975 , 1981 ) and are now commonly referred to as “Tsuchiya jets” (TJs). Their basic properties have recently been summarized by Johnson and Moore (1997) and Rowe et al. (2000) . The jets are only about 1.5° wide, attain peak speeds of 30–40 cm s −1 with a combined transport of

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Ryo Furue, Julian P. McCreary Jr., and Zuojun Yu

1. Introduction The Pacific subsurface countercurrents (SCCs) are eastward jets located along thermal fronts at the poleward edges of thermostad water. They were first reported by Tsuchiya (1972 , 1975 , 1981) , and are now commonly referred to as Tsuchiya jets (TJs). Furue et al. (2007 , hereafter F07) investigated the dynamics of the southern TJ using an ocean general circulation model (OGCM). In this follow-on paper to F07 , we extend our earlier study to consider the dynamics of the

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Xavier Couvelard, Patrick Marchesiello, Lionel Gourdeau, and Jerome Lefèvre

-scale flow entering the region, and the major Coral Sea islands (Fiji, Vanuatu, and New Caledonia) are major obstacles to the large-scale flow. Using a global numerical model [the U.K. Ocean Circulation and Advanced Modeling Project (OCCAM) at 1/4° resolution], Webb (2000) shows that the islands of the SWP are able to restructure the SEC into a series of deep, narrow jets. In this model, five jets are identified ( Fig. 2 ): the South and North Fiji jets (hereafter SFJ and NFJ), the North Vanuatu jet

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Serguei Sokolov and Stephen R. Rintoul

1. Introduction For geophysical flows of sufficient spatial scale, the meridional gradient of planetary vorticity (the β effect) provides a restoring force that helps to organize the flow into persistent, narrow zonal jets ( Rhines 1975 ). Well-known examples include the jets on Jupiter and the outer planets and the jet streams in the earth’s atmosphere. Oceanic flows also fall in a parameter range conducive to the formation of zonal jets, although the presence of land boundaries has been

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Stephanie Waterman and Brian J. Hoskins

1. Introduction Understanding the role of eddies and their interaction with the larger-scale flow in western boundary current extension (WBCE) jet systems such as the Gulf Stream and Kuroshio Extensions is critically important because WBCE jets are of fundamental importance to the dynamics of basin-scale circulations and the ocean's global transport of heat, and eddy variability plays a crucial role in WBCE jet dynamics. For example, we expect eddies and their nonlinear interactions to impact

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Igor Kamenkovich, Pavel Berloff, and Joseph Pedlosky

1. Introduction and background Our view of the ocean circulation is changing continually. The original depiction of the ocean circulation as a steady, large-scale flow has advanced to a much more complex picture with motions and variability on a wide range of spatial and temporal scales. One of the examples of the recent advances in our understanding of the ocean circulation is a discovery of multiple predominantly zonal jets. These zonal jets have been observed in the time-averaged anomalies

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