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John Marshall, David Ferreira, J-M. Campin, and Daniel Enderton

aquaplanet ocean is not that dissimilar from our own. We observe a warm lens of fluid bulging down into the subtropics to a depth of ∼1 km and markedly thinning in equatorial latitudes coinciding with bands of upwelling. The ocean is well mixed beneath the thermocline and the poles with abyssal temperatures of ∼2°C. Upwelling at high latitudes draws well-mixed abyssal fluid up toward the surface. Figure 2a shows the zonal average zonal winds (top right) and currents (bottom right). Away from boundary

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D. G. Dritschel and M. E. McIntyre

pumped global-scale circulations such as the Brewer–Dobson circulation of the terrestrial stratosphere. 1 The range of such stresses is not limited to mixing lengths, but can reach out as far as waves can propagate. And, crucially, there is a strong dynamical interplay between the more wavelike and the more turbulent aspects, not unlike the wave–turbulence interplay and stress divergence that give rise to alongshore currents in an ocean beach surf zone. Among the consequences of such interplay, in

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Cegeon J. Chan, R. Alan Plumb, and Ivana Cerovecki

represent deviations from the time average. Near the surface, we invoke Bretherton’s PV sheets ( Bretherton 1966 ), exploiting the equivalence between an inhomogeneous boundary temperature distribution and a delta function PV anomaly just inside an isothermal boundary. Then both F z and [ w̃ *] vanish at the boundary, and the divergence of EP fluxes is concentrated in the surface PV sheet. Accordingly, we first vertically integrate each of the terms in (9) through the top 1600 m for each phase of

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P. B. Rhines

1. Introduction and potential vorticity background Solar radiation bathes the earth, varying smoothly with latitude, and yet the circulations it produces are filled with small-scale transient eddies, jet streams, and boundary currents. Zonal jet stream generation occurs with thermally forced circulations on a simple, smooth globe. Instability of zonally symmetric, baroclinic circulations is often given as a primary reason for these synoptic-scale features, which are amplified or generated ab

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Edwin P. Gerber and Geoffrey K. Vallis

1. Introduction In this paper we investigate processes that determine the persistence of the zonal index and North Atlantic Oscillation (NAO), focusing on intraseasonal time scales. By intraseasonal, we mean time scales of 10–100 days, longer than those associated with synoptic variability, but not so long as to allow for significant changes in the boundary conditions or forcing, such as sea surface temperature. On these shorter periods, then, the focus is on internal processes in the

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Semion Sukoriansky, Nadejda Dikovskaya, and Boris Galperin

frequencies and smaller wavenumbers causing the anisotropization of the flow field. As a result, the energy accumulates in modes with small north–south wavenumbers that correspond to east–west currents, zonal jets, giving rise to the process of zonation. The width of the zonal jets scales with k −1 R . In a steadily forced flow, the spectrum is expected to develop a sharp peak at k R and rapidly decrease for k > k R . Items 3 and 4 have been confirmed in numerous theoretical, numerical, and

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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

“jets” of alternating sign are found with peak amplitudes of up to 0.5 cm s −1 . This banded organization of the zonal flow is also apparent in the shading of Fig. 6 , in which clear stripes or bands oriented azimuthally are clearly seen. Flow near the outer boundary, however, is predominantly retrograde, much as for case I in Fig. 5 . Eddy gyres of either sign are apparent, though they typically are found at radii in which the vorticity of the azimuthal currents are of the same sign as the gyres

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P. H. Haynes, D. A. Poet, and E. F. Shuckburgh

regions in the tropical upper troposphere, the mid- and high-latitude lower stratosphere, the Gulf Stream, and other oceanic current systems (e.g., Bower et al. 1985 ; Marshall et al. 2006 ). The significance of the similarity between the inhomogeneous transport and mixing structure seen in the kinematic time-periodic flows on the one hand and in observed or realistic atmospheric and oceanic flows on the other is not yet completely clear. The fact is that in the former the flow is imposed in advance

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Yoshi-Yuki Hayashi, Seiya Nishizawa, Shin-ichi Takehiro, Michio Yamada, Keiichi Ishioka, and Shigeo Yoden

coherently over extended periods of time, while in the lower latitudes, they are stretched and elongated in the zonal direction, and disappear. The latitudinal boundary where such vortices appear approaches equatorward with increasing Fr. It seems that the latitudes of the appearance of coherent vortices coincide with the latitudes at which the zonal mean flows become weak. The amplitudes of vortices also decrease with increasing latitude. Especially in the high latitudes for the case of Fr = 1/ 10 , it

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I. G. Watterson

dominated by the first three or four sigma levels, and hence the boundary layer. As a residual, the D term also includes vertical advection terms (including eddy terms) that do not contribute to the vertical integral, as well as parameterized diffusion and drag in the model, but these appear relatively small aloft. The F M term (not shown) is small. The terms have a similar broad structure to the Mk2 results ( Watterson 2002 ), but at double the resolution. The regression of the vertical integral of

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