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Randal D. Koster, Yehui Chang, and Siegfried D. Schubert

resolve key processes at all relevant scales. Here we use an AGCM to explore one particular mechanism for remote soil moisture impacts on meteorological fields, a mechanism involving the phase locking of a planetary wave over a specific soil moisture pattern. We start in section 2 with a diagnostic analysis of AGCM simulations. This analysis provides the information needed to design specialty simulations ( section 3 ) that confirm the operation of the mechanism within the model. Supporting evidence

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Lin Wang, Ronghui Huang, Lei Gu, Wen Chen, and Lihua Kang

EAWM was independent of the Siberian high. Since variability of the AO can significantly modulate the propagation of quasi-stationary planetary waves between the troposphere and the stratosphere ( Chen et al. 2000 , 2003 ; Chen and Huang 2005 ), Chen et al. (2005) examined the interannual AO–EAWM relationship from the perspective of the quasi-stationary planetary wave activity (PWA). They found that during the positive phase of the AO, more quasi-stationary planetary waves propagate from high

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K. Kornhuber, V. Petoukhov, D. Karoly, S. Petri, S. Rahmstorf, and D. Coumou

1. Introduction Quasi-stationary Rossby waves have a pronounced influence on weather in the midlatitudes in both the Southern and Northern Hemisphere (SH and NH, respectively) and are often associated with extreme weather events ( Hoskins and Woollings 2015 ; Screen and Simmonds 2014 ; Coumou et al. 2014 ; Woollings 2010 ). Rossby or planetary waves are large-scale oscillations of the midlatitude flow resulting from the latitudinal dependency of the Coriolis effect combined with thermal or

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Koutarou Takaya and Hisashi Nakamura

( Barnston and Livezey 1987 ). In spite of these efforts by the previous studies, mechanisms for the interannual variability of the East Asian winter monsoon have not been fully clarified yet. The Siberian high and Aleutian low, which constitute the East Asian winter monsoon system, are the prominent semipermanent pressure systems at the surface ( Fig. 1a ), as a surface manifestation of the planetary waves in winter ( Lau 1979 ; Wallace 1983 ). Figures 1b and 1c show the zonally asymmetric component

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Pu Lin, Qiang Fu, and Dennis L. Hartmann

1. Introduction Planetary wave activity accounts for a large portion of the spatial and temporal variability of the stratosphere. Its interaction with the zonal-mean flow affects the strength and the duration of the polar vortex (e.g., Mechoso et al. 1985 ; Polvani and Plumb 1992 ). Planetary wave breaking is the major driver of the equator-to-pole hemispheric Brewer–Dobson circulation (BDC) in the stratosphere (e.g., Rosenlof and Holton 1993 ; Holton et al. 1995 ). Stratospheric planetary

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Tiffany A. Shaw and Judith Perlwitz

1. Introduction Planetary-scale waves play an important role in determining the climate of the winter hemisphere. They are a particularly important component of the dynamics of the winter season in the Northern Hemisphere where they are readily forced by the combination of orography and continent–ocean heating asymmetries. Planetary waves are well known to be one of the dominant modes of coupling between the stratosphere and troposphere because of their significant vertical propagation. They

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Hua Lu, Lesley J. Gray, Ian P. White, and Thomas J. Bracegirdle

et al. 2016 ), and model biases ( Mitchell et al. 2015b ; Dhomse et al. 2016 ). It has been widely accepted that the atmospheric response to the initially small-magnitude solar radiative forcing must involve amplification via nonlinear processes ( Gray et al. 2010 ). One classic mechanism involves the dynamical interaction between upward-propagating planetary-scale Rossby waves (planetary waves hereafter) and the background westerly flow in the winter stratosphere. When a critical layer in a

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Damien Irving and Ian Simmonds

1. Introduction The relationship between mid- to upper-tropospheric planetary wave activity and regional climate variability in the Northern Hemisphere (NH) has received a great deal of attention in recent times, as researchers try to better understand the links between the Arctic amplification and midlatitude weather (e.g., Cohen et al. 2014 ; Screen and Simmonds 2014 ). While the meridional temperature gradient has not undergone such dramatic changes in the Southern Hemisphere (SH), this

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Christopher C. Chapman, Bernadette M. Sloyan, Terence J. O’Kane, and Matthew A. Chamberlain

). Since the time scales are considerably longer in the ocean than in the atmosphere, oceanic teleconnections can provide a mechanism for interseasonal and interannual predictions. Of particular interest are long baroclinic planetary waves (LPWs), which have the following characteristics ( Killworth et al. 1997 ; Killworth and Blundell 1999 ; Maharaj et al. 2007 ): wavelengths that are long relative to the local deformation radius R D ; periods that are long relative to the inertial period f −1 of

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Sukyoung Lee, Steven Feldstein, David Pollard, and Tim White

reflectivity due to a reduction in the number of cloud condensation nuclei ( Kump and Pollard 2008 ). In this study, we propose and then test the mechanism that enhanced and localized tropical convection can also trigger high-latitude warming through the excitation of poleward-propagating planetary-scale Rossby waves, which transport heat poleward and induce sinking motions. Our proposed mechanism is based on the premise that under the high CO 2 loading conditions, tropical convection was more intense and

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