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M. L. R. Liberato, J. M. Castanheira, L. de la Torre, C. C. DaCamara, and L. Gimeno

point of view of the energy associated with the forcing waves. The main goal of this work is therefore to perform a diagnostic study of the total (i.e., kinetic + available potential) energy associated with the planetary waves that force the vortex dynamics. The analysis is based on a three-dimensional (3D) normal mode decomposition of the atmospheric global circulation, which is partitioned into planetary Rossby waves and inertio–gravity waves, both types of waves possessing barotropic and

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Yasuko Hio and Shigeo Yoden

SH. The wave–wave interaction between the stationary “planetary wave of zonal wavenumber 1” (hereafter denoted as “Wave 1”) and eastward propagating Wave 2 was investigated in HY04 with the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis dataset over 20 years. The stationary Wave 1 is generated in the troposphere mainly by zonally asymmetric lower boundary conditions and has significant interannual variations ( Hio and Hirota 2002

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Robert X. Black and Brent A. McDaniel

-term trends ( Thompson and Solomon 2002 ; Gillett and Thompson 2003 ). The stratospheric polar vortex is characterized by an annual cycle that terminates with a relatively rapid breakdown known as the stratospheric final warming (SFW), which typically occurs during spring. However, considerable interannual variability in the timing of SFW events is observed (e.g., Waugh and Rong 2002 ) since they are initiated by transient Rossby wave packets propagating upward from tropospheric altitudes. This raises

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Thomas Jung and Peter B. Rhines

most of the skill of 10-day forecasts of the midlatitudinal atmospheric flow arises from the predictability of the long waves). However, the relatively high predictability of zonal pressure-drag events across Greenland is consistent with our notion that planetary wave propagation, which is relatively predictable, is crucial in determining synoptic-scale developments associated with the Greenland massif. 4. Discussion We have used the zonal pressure drag time series on south Greenland as a tool to

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P. B. Rhines

this focal system. We now can see disturbances in many parts of the fluid, most strongly in the topographic waves over the mountain and an intense wake south of and downstream of the mountain. This entire structure is a result of the winding property of topographic waves, which create a spiral pattern above the mountain, initially as transients, but soon thereafter as arrested, standing, spiral waves. The lee wake is a jetlike concentration of the circulation (analogous to the Greenland atmospheric

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O. Martius, C. Schwierz, and H. C. Davies

. Geophys. Res. , 101 , 1435 – 1456 . Balasubramanian , G. , and S. T. Garner , 1997 : The role of momentum fluxes in shaping the life cycle of a baroclinic wave. J. Atmos. Sci. , 54 , 510 – 533 . Benedict , J. J. , S. Lee , and S. B. Feldstein , 2004 : Synoptic view of the North Atlantic Oscillation. J. Atmos. Sci. , 61 , 121 – 144 . Bjerknes , J. , 1969 : Atmospheric teleconnections from the equatorial Pacific. Mon. Wea. Rev. , 97 , 163 – 172 . Bjerknes , J. , and H

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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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Yuji Kitamura and Keiichi Ishioka

1. Introduction It is known that two-dimensional turbulence possesses aspects different from three-dimensional turbulence. Unlike 3D turbulence, vortices of the same sign tend to merge and spontaneously form a larger flow structure in 2D turbulence ( Lilly 1969 ; McWilliams 1984 ). Since quasigeostrophic turbulence, which is approximately valid in atmospheric motions on synoptic scales, is analogous to 2D turbulence ( Charney 1971 ), knowledge for 2D turbulence on a rotating plane provides the

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Robert X. Black and Brent A. McDaniel

winter terminates with a relatively rapid breakdown of the polar vortex known as the stratospheric final warming (SFW), marking the final transition from westerlies to easterlies in the extratropical stratosphere. There is considerable interannual variability in the timing of SFW events ( Waugh and Rong 2002 ) since they are sensitive to the preexisting stratospheric flow structure and variations in the upward propagation of tropospheric planetary waves ( Waugh et al. 1999 ). SFW events are more

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D. G. Dritschel and M. E. McIntyre

values of . As is well known, the existence and statistical persistence of this feature used to be regarded as a major enigma of atmospheric science (e.g., Lorenz 1967 , 149–151; Starr 1968 ). Figure 1 , then, can be taken as a reminder of the main concepts needed to solve that enigma, indeed to solve it in a remarkably robust and simple way. They are (i) the PV invertibility principle and its corollaries (which include making sense of the Rossby wave mechanism itself), (ii) the fact that breaking

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