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Jean-Baptiste Gilet, Matthieu Plu, and Gwendal Rivière

1. Introduction Intense storms in the northeastern Atlantic Basin evolve following a variety of complex life cycles. An often observed cycle consists of an appearance in the southern part of an upper-level large-scale jet, eastward translation without significant amplification on this anticyclonic side, and then sudden and intense growth while the depression crosses the jet axis. The Christmas 1999 Lothar storm over Europe is one example ( Rivière and Joly 2006b ). Similar but less spectacular

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Hugh S. Baker, Tim Woollings, and Cheikh Mbengue

1. Introduction The eddy-driven jet and associated storm track contribute to much of the weather and climate in the midlatitudes. Changes in the midlatitude eddy-driven jet stream latitude are one of the most robust circulation signs of climate change. Studies using the CMIP models find shifts, changes in amplitude, and changes in variability of the jets ( Woollings et al. 2012 ; Barnes and Polvani 2013 ; Simpson et al. 2014 ; IPCC 2013 ). However, the magnitudes of these changes are

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Dan-Qing Huang, Jian Zhu, Yao-Cun Zhang, Jun Wang, and Xue-Yuan Kuang

(%) of (a) rainfall frequency to annual total rainfall frequency and (b) rainfall amount to annual total rainfall amount during the SPR period in 1960–2011. Previous studies have suggested a strong linkage between the spring rainfall over southern China and the East Asian subtropical jet (EASJ) (e.g., Lu et al. 2013 ). For example, Wen et al. (2007) emphasized the contribution of the zonal momentum advection of the EASJ to the vertical circulation over southern China. The variation of the EASJ

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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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Kunio M. Sayanagi, Adam P. Showman, and Timothy E. Dowling

1. Introduction Spacecraft observations of Jupiter reveal ∼30 zonal jets at the cloud level. In the equatorial region, a fast, broad, eastward jet dominates the flow flanked by westward jets to the north and south. Vortices are absent in the equatorial region roughly between ±20° latitudes. Outside of the equatorial region, numerous zonal jets exist up to ±60° latitudes. Many of the jets contain stable vortices that drift in the east–west direction at speeds slightly different from the

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Shin Takehiro, Michio Yamada, and Yoshi-Yuki Hayashi

numerical experiments of decaying turbulence on a rotating sphere with full spherical geometry. They investigated the statistical tendency for the development of a flow field from a random set of initial states and found that a banded structure of zonal flows emerges and that there was a tendency for circumpolar flows to be easterly jets. However, especially in cases when the rotation rate is large, their initial fields are in a state of “wave turbulence”; that is, the initial kinetic energy spectrum is

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Takeaki Sampe and Shang-Ping Xie

moisture. The meiyu-baiu onset is associated with a northward shift in the NPSH axis to about 25°N and the migration of the upper-level westerly jet over Eurasia to the north of the Tibetan Plateau. The jet is located on the northern flank of the Tibetan high centered around 25°–30°N in the upper troposphere in response to intense monsoon convection ( Tao and Chen 1987 ; Li and Yanai 1996 ). At the surface, a planetary-scale low is formed over the continent, accentuated by land–sea surface temperature

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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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Clemens Spensberger, Thomas Spengler, and Camille Li

1. Introduction Jet streams are often identified using a wind speed threshold that defines the perimeter and hence the body of a jet stream (e.g., Koch et al. 2006 ; Strong and Davis 2007 ). Such identification schemes often detect large coherent areas as one jet body, thereby obscuring the existence of multiple wind speed maxima within one body. For example, in the winter snapshots in Figs. 2b and 2c of Koch et al. (2006) , almost all visible wind maxima are encompassed by only one jet body

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Dana L. Doubler, Julie A. Winkler, Xindi Bian, Claudia K. Walters, and Shiyuan Zhong

1. Introduction Our understanding of the spatial and temporal variations of low-level wind maxima (commonly referred to as low-level jets or LLJs) over North America and surrounding coastal areas remains incomplete in spite of their significant impact on local and regional weather and climate. This is in part due to the limited availability of upper-level wind observations. The majority of previous LLJ climatologies were developed using routine rawinsonde observations (e.g., Bonner 1968

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