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Yoshi N. Sasaki and Niklas Schneider

1. Introduction After leaving the coast of Japan around 35°N, the Kuroshio penetrates as a free jet into the North Pacific as the Kuroshio Extension (KE) and retains its sharp jet structure with associated fronts to the date line and beyond. The KE jet reaches its maximum speed on the order of 1 m s −1 at the surface and is accompanied by meridional potential vorticity (PV) gradients at the jet axis that are much larger than the planetary vorticity gradient ( Fig. 1 ). Fig . 1. A meridional

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Ekaterina Ezhova, Claudia Cenedese, and Luca Brandt

1. Introduction This study focuses on the dynamics of an axisymmetric vertical turbulent jet in a stratified fluid. Vertical turbulent jets may serve as models of numerous flows both in nature and industry (see, e.g., Turner 1973 ; List 1982 ; Hunt 1994 ), including effluents from submerged wastewater outfall systems in the ocean (e.g., Jirka and Lee 1994 ), convective cloud flows in the atmosphere, pollutant discharge from industrial chimneys, and subglacial discharge from glaciers (e

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P. Berloff, I. Kamenkovich, and J. Pedlosky

1. Introduction The principal phenomenon studied in this paper is the existence of multiple, alternating zonal jets in the oceans. The observational evidence of these jets emerged mostly over the last few years, and their theoretical understanding is incomplete. In this introduction we pose the problem, discuss the background, and describe the ocean model. The phenomenology of the modeled jets is described in section 2 . Section 3 focuses on the kinematical analysis, section 4 on the

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Antoine Venaille and Freddy Bouchet

, existing theories give no clear explanation of the existence of strong and robust eastward jets in the inertial part of these currents. The classical wind-driven ocean theory and the inertial approach both give an incomplete picture and complement each other. A useful step toward a comprehensive nonequilibrium theory that would combine both approaches is to study midbasin eastward jets in the inertial limit. Such is the focus of this paper. On the one hand, the problem of the self-organization of a

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Audrey Delpech, Sophie Cravatte, Frédéric Marin, Yves Morel, Enzo Gronchi, and Elodie Kestenare

equator ( Firing et al. 1998 ). In the tropical Pacific, pioneer cruises ( Tsuchiya 1975 ; Eriksen 1981 ; Firing 1987 ; Firing et al. 1998 ; Rowe et al. 2000 ; Gouriou et al. 2001 ) revealed the presence of several persistent zonal currents below the thermocline in the near-equatorial band. Among them, the Tsuchiya jets are eastward currents found in the whole basin just below the thermocline between 2.5° and 5° from the equator, with intensities of 20–40 cm s −1 ( Rowe et al. 2000 ). The North

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Andrew F. Thompson

1. Introduction Ocean flows are replete with coherent structures on scales ranging from the Rossby deformation radius λ , tens of kilometers, to the size of ocean basins, many thousands of kilometers. Ocean jets, defined as zonally elongated flows typically exhibiting banded structure with alternating eastward and westward velocities, are an example of coherent structures observed throughout this range of scales. The near-universal presence of jets in the ocean has been substantiated by

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Emma J. D. Boland, Andrew F. Thompson, Emily Shuckburgh, and Peter H. Haynes

1. Introduction A number of studies have identified and noted the potential impact of zonal jet structure (alternating eastward and westward velocities) on ocean circulation ( Berloff et al. 2009 ; Maximenko et al. 2005 ), yet many instances of nonzonal jet orientation are also evident. Observations of sea surface height indicate jet cores at topographic gradient maxima ( Hughes and Ash 2001 ) and also reveal increased eddy forcing of jets near topographically complex regions ( Maximenko et al

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Yoshi N. Sasaki, Shoshiro Minobe, and Niklas Schneider

1. Introduction The Kuroshio Extension (KE) jet, the western boundary current of the subtropical gyre in the North Pacific, transports warm water poleward and yields large heat release from the ocean to the atmosphere. The KE jet exhibits large fluctuations on interannual and decadal time scales (e.g., Deser et al. 1999 ; Schneider et al. 2002 ; Qiu and Chen 2005 ), so its variability has attracted much attention owing to its significant roles not only in the interior ocean structure of the

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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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