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Paul D. Williams and Christopher W. Kelsall

1. Introduction Zonal jets in planetary atmospheres and oceans affect the transport of heat, momentum, and tracers. Satellite observations show clear evidence of multiple alternating zonal jets extending from the equator to the polar regions in the atmospheres of Jupiter ( Limaye 1986 ) and Saturn ( Sanchez-Lavega et al. 2000 ). In numerical simulations of the atmospheres of Jupiter, Saturn, Uranus, and Neptune, jets are found to emerge spontaneously from random initial conditions, in good

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Bing Pu and Robert E. Dickinson

source that sets up a large-scale mountain–lowland circulation pattern with subsidence over the Great Plains—inhibiting convection during the afternoon.... Moist instabilities...initiate convection in rising air over the lee of the Rockies, propagating to the east.... The moisture supply for these storms the low-level jet, aiding in the setup of convective ‘corridors’ for intense storms” (p. 1231). Various authors have identified processes in models responsible for their lack of success in

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F. J. Beron-Vera, M. G. Brown, M. J. Olascoaga, I. I. Rypina, H. Koçak, and I. A. Udovydchenkov

1. Introduction In Rypina et al. (2007a) , it was argued that the transport barrier near the core of the austral polar night jet can be explained by a mechanism different from the potential vorticity (PV) barrier mechanism ( Juckes and McIntyre 1987 ). The new barrier mechanism, which was subsequently referred to as strong KAM stability ( Rypina et al. 2007b ), follows from an argument that does not make use of dynamical constraints on the streamfunction. This necessitates that dynamical

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Kirsty E. Hanley and Stephen E. Belcher

light winds (less than 2 m s −1 ) and fast-traveling swells, namely upward momentum transfer from the ocean to the atmosphere ( Grachev and Fairall 2001 ) and the occurrence of low-level wind jets ( Smedman et al. 1999 ). Such features are thought to be characteristic of a wave-driven wind regime. This regime was first reported by Harris (1966) , who found that in laboratory wave tank experiments, a progressive water wave led to airflow directly above the waves with a mean component in the

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Amanda K. O'Rourke and Geoffrey K. Vallis

1. Introduction The maintenance and variability of the zonal mean zonal flow in the midlatitude upper troposphere can be linked to the eddy momentum fluxes of planetary-scale Rossby waves ( Limpasuvan and Hartmann 2000 ). The eddy momentum flux associated with these waves is strongly tied to their meridional propagation through the upper troposphere. The meridional propagation of eddies is highly sensitive to the structure of the background flow—namely, the subtropical and eddy-driven jets

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Peter L. Read, Yasuhiro H. Yamazaki, Stephen R. Lewis, Paul D. Williams, Robin Wordsworth, Kuniko Miki-Yamazaki, Joël Sommeria, and Henri Didelle

1. Introduction The banded organization of clouds and zonal winds in the atmospheres of the outer planets has long fascinated atmosphere and ocean dynamicists and planetologists, especially with regard to the stability and persistence of these patterns. This banded organization, mainly apparent in clouds thought to be of ammonia and NH 4 SH ice, is one of the most striking features of the atmosphere of Jupiter. The cloud bands are associated with multiple zonal jets of alternating sign with

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Wenbo Tang, Manikandan Mathur, George Haller, Douglas C. Hahn, and Frank H. Ruggiero

as DLE ridges, even though they do not induce exponential separation of particles. To distinguish these shear-type LCS from hyperbolic (i.e., attracting or repelling) LCS, we use stability results from Haller (2002) . Shear-type LCS turn out to play an important role in the present flow, as these LCS act as Lagrangian boundaries of a subtropical jet stream. The dataset we analyze here contains high-resolution three-dimensional numerical weather prediction simulations combined with in situ

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Brad E. Beechler, Jeffrey B. Weiss, Gregory S. Duane, and Joseph Tribbia

in errors of location. Models produce structures such as cyclones, storm fronts, and jet streaks but may not be able to predict all-important characteristics of these structures. Forecast model bias is a persistent problem in numerical modeling and data assimilation ( Dee and da Silva 1998 ). For instance, Alexander et al. (1998) show that the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) model has trouble accurately

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Loïc Robert, Gwendal Rivière, and Francis Codron

1. Introduction Midlatitude jets are also called eddy-driven jets because they are maintained against surface drag by the convergence of momentum by eddies ( Vallis 2006 ). These eddies in turn develop in regions of strong baroclinicity, which tend to follow the jet position through thermal wind balance. The eddies and the jet are thus tightly coupled and how their interaction influences the variability of the jet is still not fully understood. The convergence of eddy momentum fluxes, herein

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Alan Shapiro, Evgeni Fedorovich, and Joshua G. Gebauer

Rapid Update Cycle (RUC) wind analyses. In a 20-yr climatology of warm season nocturnal CI over the central and southern Great Plains, Reif and Bluestein (2017) found that 24% of the nocturnal CI episodes occurred without a nearby surface boundary. Nearly one-half of these no-boundary (NB) CI episodes were of a linear storm type, the majority of which had a preferred north–south orientation, the same preference exhibited by nocturnal low-level jets (LLJs) over the Great Plains (e.g., Hoecker 1963

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