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Cory Baggett and Sukyoung Lee

forced planetary-scale waves can warm the Arctic ( Lee et al. 2011a , b ; Yoo et al. 2012 ; Lee 2012 ; Ding et al. 2014 ), we ask the following: Do these planetary-scale waves tap this vast reservoir of ZAPE without relying on the flux–gradient relationship? This was conjectured previously ( Lee 2014 ), but its validity has not been tested. In this study, we address this question by comparing the life cycles of planetary-scale and synoptic-scale waves. Because Rossby waves propagate from the

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Dehai Luo, Tingting Gong, and Yina Diao

(2006a , hereafter AM06a ) noted that the planetary wave breaking (PWB) that occurs in the subtropical Atlantic may amplify the positive NAO. On the other hand, it has been demonstrated in observational studies that the NAO phenomenon is characterized by a meridional displacement of the upper-tropospheric jet where positive and negative phases correspond, respectively, to the northward and southward movements of a westerly jet ( B04 ; F04 ; Riviere and Orlanski 2007 ), thus concluding that wave

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A. Hannachi

1. Background and motivation The dynamics of low-frequency variability have been, and still are, the focus of many research studies. This continuous interest is driven by the need to understand the dynamics of tropospheric planetary waves and other synoptic patterns such as blocking for predictability. The issue of climate change has also brought the question related to the existence of preferred flow regimes up front in science media ( Palmer 1999 ; Corti et al. 1999 ; Hsu and Zwiers 2001

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Tiffany A. Shaw and Judith Perlwitz

1. Introduction During Northern Hemisphere (NH) winter, the stratosphere deviates significantly from radiative equilibrium because of the interaction of the stratospheric zonal-mean flow and planetary-scale waves, which propagate upward from the troposphere. The convergence of Eliassen–Palm (EP) flux by planetary-scale waves drives the equator-to-pole residual circulation that produces upwelling in the tropics and downwelling in high latitudes ( Dunkerton et al. 1981 ; McIntyre and Palmer 1983

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Lawrence Coy, Stephen Eckermann, and Karl Hoppel

1. Introduction Sudden stratospheric warmings (SSWs) are a major component of the stratospheric circulation. Over the course of a few days the wintertime westerly stratospheric polar vortex is disrupted and the midstratospheric temperatures in the polar night increase rapidly by as much as 60 K (see Andrews et al. 1987 ). These dramatic changes are produced when strong planetary-scale Rossby wave forcing in the troposphere leads to Rossby wave breaking and dissipation in the stratosphere (see

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Junjun Liu and Tapio Schneider

that absolute vorticity is not mixed across the equator but separately by the Rossby wave lobes on either side of the equator. Fig . 10. Latitudinal absolute vorticity profiles. The blue line shows the planetary vorticity f = 2Ωsin ϕ ; the dashed magenta line shows the end state of homogenized absolute vorticity in each hemisphere; and the solid magenta line shows the absolute vorticity at 2 bar in the simulation with an intrinsic heat flux of 35.0 W m −2 , Δ s = 0.4, and no drag in the

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Elmar R. Reiter and Daniel Westhoff

732 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUME38 -A Planetary-Wave Climatology ELMAR R. REITER AND DANIEL WESTHOFFDepartment of Atmospheric Science, Colorado State University, Fort Collins 80523(Manuscript received 30 September 1980, in final form 23 December 1980)ABSTRACT Ultralong and long planetary waves are analyzed at the 500 mb level in terms of their amplitudes, phasesand

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R. S. Lieberman, J. France, D. A. Ortland, and S. D. Eckermann

is a measure of planetary wave (PW) activity, the reported correlation implies the imprinting of strong wintertime stratospheric PW activity upon the anomalously warm summer mesopause. Quite recently, Smith et al. (2020) argued that statistically, the summer mesosphere warming is an extension of the wave-driven winter hemisphere circulation that arises from global wind balance and mass continuity requirements. However, most theoretical investigations into this so-called interhemispheric

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Ángel F. Adames and John M. Wallace

levels. In tutorials for lay audiences, the atmospheric circulation during El Niño is often depicted as a weakening of a deep overturning circulation cell in the equatorial plane, referred to by Bjerknes (1969) as the “Walker circulation.” However, in reality the tropical atmospheric signature of ENSO is fully three-dimensional, and it involves regional features, equatorial planetary waves, and the zonally symmetric circulation. The sea level pressure (SLP) signature of ENSO, known as the Southern

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Anne L. Laraia and Tapio Schneider

-tropospheric zonal wind at the equator vs , with fixed values of and γ . For all three curves, . For faster planetary rotation rates, the equatorial winds become more westerly with decreasing (cf. third and fourth rows in Fig. 1 ). This is in line with the notion that larger meridional temperature gradients produce stronger baroclinic instability in midlatitudes, leading to off-equatorial wave generation and angular momentum flux divergence near the equator. For slower rotation rates, however, the

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