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Keiichi Ishioka, Jitsuko Hasegawa, and Shigeo Yoden

1. Introduction Spontaneous zonal jet formation is a well-known significant feature in two-dimensional β -plane turbulence ( Rhines 1975 ; Vallis and Maltrud 1993 ). The formation itself is considered due to the upward cascade of energy that favors a zonal structure because of the β term. Vallis and Maltrud (1993) found asymmetry between eastward and westward jet profiles that emerged from turbulent states in the forced-dissipative numerical experiments. That is, eastward jets are

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Janni Yuval and Yohai Kaspi

1. Introduction The current understanding is that two types of jets exist in the atmosphere: a subtropical jet (STJ) and an eddy-driven jet (EDJ), also referred to in the literature as the subpolar jet. Two different mechanisms are responsible for the existence of these jets. The STJ is primarily driven by the advection of planetary angular momentum by the thermally direct Hadley circulation ( Held and Hou 1980 ), and eddies usually act to weaken this jet. On the other hand, the EDJ is driven

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Brian F. Farrell and Petros J. Ioannou

1. Introduction Coherent jets that are not forced at the jet scale are often observed in turbulent flows, with a familiar geophysical-scale example being the banded winds of the gaseous planets ( Ingersoll 1990 ; Vasavada and Showman 2005 ; Sánchez-Lavega et al. 2008 ). In the earth’s midlatitude troposphere, the polar-front jets are eddy driven ( Jeffreys 1933 ; Lee and Kim 2003 ). The earth’s equatorial stratosphere is characterized by the eddy-driven quasi-biennial oscillation (QBO) jet

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Lindsey N. Williams, Sukyoung Lee, and Seok-Woo Son

1. Introduction One peculiar feature in the atmosphere, which does not seem to have received much attention, is the fact that large-scale westerly jets, at times, take on a spiral form. An example of the spiral jet structure is shown in Fig. 1 , which displays the 275-hPa Southern Hemisphere (SH) zonal wind field, corresponding approximately to a 40-yr calendar mean of 27 April. A more precise description of the data and averaging procedure will be given in section 2 . Starting from the

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Tapio Schneider and Junjun Liu

1. Introduction The zonal flow in Jupiter’s upper troposphere has been inferred by tracking cloud features, which move with the horizontal flow in the layer between about 0.5 and 1 bar atmospheric pressure ( Ingersoll et al. 2004 ; West et al. 2004 ; Vasavada and Showman 2005 ). In this layer, the zonal flow is organized into a strong prograde (superrotating) equatorial jet and an alternating sequence of retrograde and prograde off-equatorial jets ( Fig. 1a ). This flow pattern has been

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Adam J. French and Matthew D. Parker

elevated (ingesting parcels from above approximately 500 m), the mechanism responsible for lifting inflowing parcels evolved from a cold pool to a bore. In the interest of simplicity, the simulations of P08 utilized a homogeneous background wind profile that did not include a low-level wind maximum, or low-level jet (LLJ), which is commonly observed in nocturnal MCS environments (e.g., Maddox 1983 ; Cotton et al. 1989 ). While numerous previous studies have highlighted the importance of the LLJ as

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Brian F. Farrell and Petros J. Ioannou

1. Introduction Large-scale coherent jets for which no obvious jet-scale forcing can be ascribed are often observed in turbulent flows; examples include the banded winds of the gaseous planets ( Ingersoll 1990 ; Vasavada and Showman 2005 ) and the earth’s midlatitude jets. This phenomenon of spontaneous jet organization in turbulence has been extensively investigated in observational and in theoretical studies ( Williams 1979 , 2003 ; Panetta 1993 ; Nozawa and Yoden 1997 ; Huang and

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S. E. Nicholson, A. I. Barcilon, M. Challa, and J. Baum

1. Introduction The tropical easterly jet stream (TEJ) is one of the most intense circulation features over Africa. This jet lies in the upper troposphere and extends from Asia to West Africa, reaching core speeds in excess of 35 m s −1 . It spans some 20°–30° of latitude. Most research on the TEJ has been in the context of the Indian monsoon ( Mishra 1987 ; Chen and Yen 1991 , 1993 ; Chen and van Loon 1987 ). It is considered to be an active player in the monsoon system. Specifically, waves

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J. B. Marston, E. Conover, and Tapio Schneider

; Majda and Wang 2006 ), generally cannot be used in developing statistical closures for such flows. In this paper, we investigate the inhomogeneous statistics of what may be the simplest flow subject to rotation, large-scale forcing, and dissipation that exhibits mixing and no-mixing regions in statistically steady states: barotropic flow on a rotating sphere driven by linear relaxation toward an unstable zonal jet. Depending on a single control parameter, namely the relaxation time, this prototype

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Changhyun Yoo and Sukyoung Lee

1. Introduction Multiple zonal jets are ubiquitous not only in planetary atmospheres (e.g., Jupiter and Saturn), but also in the earth’s atmosphere and ocean. The satellite-derived total ozone data, analyzed by Hudson et al. (2003) , show three distinctive regions separated by two boundaries in the earth’s atmosphere. One boundary closely coincides with the subtropical jet and the other with the polar-front jet. Recently, high-resolution ocean models ( Nakano and Hasumi 2005 ; Richards et al

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