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Reinhard Schiemann, Daniel Lüthi, and Christoph Schär

1. Introduction Little time had passed after aircraft pilots’ early confrontations with jet streams when meteorologists started to attach high importance to these flow features. Much of the rationale for studying jet stream variability is based on its dynamical significance in synoptic-scale cyclogenesis ( Sutcliffe 1939 , 1947 ; Nakamura 1992 ; Baehr et al. 1999 ; Wernli et al. 2002 ) and other phenomena dynamically linked to jet variability such as atmospheric blocking and the propagation

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D. G. Dritschel and M. E. McIntyre

stratified, rotating systems, are three interrelated phenomena on which this review will focus: first the spatial inhomogeneity of PV mixing by layerwise-two-dimensional turbulence, second the common occurrence of “antifrictional” or upgradient horizontal stresses , and third the spontaneous creation and self-sharpening, or narrowing, of jets. The three phenomena are all illustrated by the typical jet-sharpening scenario sketched in Fig. 1 . The sketch was originally made to help understand the

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Rei Chemke and Yohai Kaspi

1. Introduction One of the most robust phenomena in geophysical fluid dynamics is the emergence of jets. These jets have a large impact on the dynamics of the atmosphere and ocean mostly through eddy–mean flow interactions and appear in both terrestrial and gas planets (e.g., Williams 1978 ; Panetta 1993 ; Schneider 2006 ). Because of their strong dependence on temperature gradients and heat fluxes in the atmosphere, these jets shape and feed off the zonal climatic bands on Earth

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Courtenay Strong and Robert E. Davis

( Thompson and Wallace 1998 , 2000a , b ). Stochastic modeling indicates the role that jet stream migration may play in the presence of such meridional dipoles (e.g., Wittman et al. 2005 ). Models of random motions constrained to conserve mass and momentum, moreover, show that meridional dipole structures robustly arise in geopotential height and zonal wind EOF analyses and may take on annular (AO like) or zonally localized (NAO like) configurations depending on the model’s zonal correlation structure

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Dan-Qing Huang, Jian Zhu, Yao-Cun Zhang, and An-Ning Huang

; Kharin et al. 2013 ). Understanding the spatial and temporal variation of summer precipitation in eastern China and its possible factors will have great benefits to the society and economy. Previous studies have suggested a strong linkage between the summer rainfall in eastern China and the two extratropical atmospheric jets over East Asia: the East Asian subtropical jet (EASJ) and the East Asian polar front jet (EAPJ). The EASJ is part of the global subtropical jet that forms along the poleward side

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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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Robert M. Banta, Larry Mahrt, Dean Vickers, Jielun Sun, Ben B. Balsley, Yelena L. Pichugina, and Eric J. Williams

not been described in previous SBL studies. Above these two layers turbulence may still be active at higher levels, sometimes associated with low-level jets (LLJs) when present. Existing analyses of the CASES-99 dataset have emphasized the importance of shear-generated turbulence near the LLJ and coupling with the ground surface (e.g., Blumen et al. 2001 ; Poulos et al. 2002 ; Mahrt and Vickers 2002 ; Banta et al. 2002 , 2003 , 2006 ; Newsom and Banta 2003 ; Sun et al. 2002 , 2004

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Andrew C. Winters, Daniel Keyser, Lance F. Bosart, and Jonathan E. Martin

1. Introduction The instantaneous positions of the polar and subtropical jets are closely related to the pole-to-equator tropopause structure, as indicated by the idealized vertical cross section in Fig. 1a . In the Northern Hemisphere, the average location of the polar jet is near 50°N in the region where the tropopause height abruptly rises from the polar tropopause (~350 hPa) to the subtropical tropopause (~250 hPa). The polar jet also resides atop the strongly baroclinic- and tropospheric

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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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