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Olivia Martius

1. Introduction a. Rationale The subtropical jet is a salient feature of the subtropical upper-level flow and a key player in the dynamical processes that link the tropics with the subtropics and the extratropics. Of central importance is the role that the subtropical jet (STJ) plays in governing Rossby wave dynamics. The STJ is coaligned with a band of strong potential vorticity (PV) gradients and therefore acts as a waveguide for synoptic-scale Rossby waves ( Hoskins and Ambrizzi 1993

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Junjun Liu and Tapio Schneider

1. Introduction Among the most striking features of the giant planets are the alternating zonal jets. As shown in Fig. 1 , Jupiter and Saturn have prograde equatorial jets (superrotation) that peak at ∼100 m s −1 and ∼200–400 m s −1 , depending on the vertical level considered. Uranus and Neptune have retrograde equatorial jets (subrotation) that peak at ∼100 m s −1 and ∼150–400 m s −1 . Jupiter and Saturn have multiple off-equatorial jets in each hemisphere; Uranus and Neptune have only a

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Adam H. Monahan and John C. Fyfe

general circulation models (e.g., Fyfe et al. 1999 ) and is related to (but not identical with; cf. Monahan and Fyfe 2008 , hereafter MF08 ) the leading mode of zonal-mean geopotential height variability (the annular mode). As noted in Wittman et al. (2005) , the ubiquity of this dipolar structure suggests that it reflects some generic feature of variability of the extratropical atmosphere—in particular, the existence of a jet in zonal-mean zonal winds characterized by fluctuations in position

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Andrew J. Monaghan, Daran L. Rife, James O. Pinto, Christopher A. Davis, and John R. Hannan

1. Introduction a. Background Diurnally varying low-level jets (LLJs) occur in many regions across the planet ( Stensrud 1996 ). However, examining the causality, frequency, and impacts of these phenomena with a comprehensive and global approach has not been possible until now because of the coarse spatial (>100 km) and temporal (6-hourly) resolution of existing global reanalyses. The companion paper to this study ( Rife et al. 2010 , hereafter R10 ) introduced a new hourly, 40-km global

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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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Yohai Kaspi and Glenn R. Flierl

1. Introduction Strong zonal winds dominate the atmospheres of the four big outer planets of the solar system. All four planets exhibit latitudinal banding and strong jet streams, where the wind velocities on Saturn are the strongest reaching more than 400 m s −1 near the equator, and Jupiter has the most structure with at least six alternating bands of east–west winds in each hemisphere ( Ingersoll 1990 ; Porco et al. 2003 ). Unlike Earth, the solid centers are small fractions of the giant

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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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Edward I. Tollerud, Fernando Caracena, Steven E. Koch, Brian D. Jamison, R. Michael Hardesty, Brandi J. McCarty, Christoph Kiemle, Randall S. Collander, Diana L. Bartels, Steven Albers, Brent Shaw, Daniel L. Birkenheuer, and W. Alan Brewer

1. Introduction Previous studies of the low-level jet (LLJ) have helped to establish its role as the major conveyor of low-level moisture from the Gulf of Mexico into the central United States ( Stensrud 1996 ; Higgins et al. 1996 ). Higgins et al. (1997) estimate that the contribution of the LLJ to low-level moisture transport over the central plains is almost 50% above average non-LLJ values. A major factor in the LLJ contribution to central plains precipitation is the relationship between

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Brian F. Farrell and Petros J. Ioannou

1. Introduction Coherent jets are often observed in turbulent flows, with the banded winds of Jupiter constituting a familiar and frequently studied example ( Ingersoll 1990 ; Vasavada and Showman 2005 ; Sánchez-Lavega et al. 2008 ). This phenomenon of spontaneous jet formation in turbulence has been studied observationally and theoretically ( Rhines 1975 ; Williams 1979 , 2003 ; Panetta 1993 ; Nozawa and Yoden 1997 ; Huang and Robinson 1998 ; Manfroi and Young 1999 ; Vallis and

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Matthew H. Hitchman and Amihan S. Huesmann

1. Introduction The stratospheric quasi-biennial oscillation (QBO; Reed et al. 1961 ; Wallace 1973 ; Baldwin et al. 2001 ), with its irregular (22–32 months) periodic reversal in zonal wind, creates long-lasting anomalies that influence the globe. In 1980, Holton and Tan (1980) discovered a significant correlation between QBO westerlies (W) at 50 hPa and the strength of the boreal polar night jet (PNJ). They suggested that sudden stratospheric warmings are less likely during QBO W, when

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