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, our analysis will show that split and displacement SSWs indeed have very distinct prewarming evolutions. However, in contrast to Charlton and Polvani (2007) and Bancala et al. (2012) , who focused on planetary waves in the region below 30 km (10 hPa), we extend our analysis upward to 55 km (0.5 hPa) and analyze the combined effects of both planetary waves and gravity waves on vortex preconditioning and the resonant excitation theory of SSWs. In doing so, we focus particular attention on split
, our analysis will show that split and displacement SSWs indeed have very distinct prewarming evolutions. However, in contrast to Charlton and Polvani (2007) and Bancala et al. (2012) , who focused on planetary waves in the region below 30 km (10 hPa), we extend our analysis upward to 55 km (0.5 hPa) and analyze the combined effects of both planetary waves and gravity waves on vortex preconditioning and the resonant excitation theory of SSWs. In doing so, we focus particular attention on split
climate, including the surface westerlies and the horizontal distribution of temperature. In the tropics, baroclinic instability is inhibited by weak rotation and small horizontal temperature gradients. Here, quasi-stationary equatorial planetary waves forced by the latent heat release from deep convection play a key role in the large-scale atmospheric circulation. Equatorial planetary waves are readily observed in the climatological-mean tropical circulation and are dominated by 1) an equatorially
climate, including the surface westerlies and the horizontal distribution of temperature. In the tropics, baroclinic instability is inhibited by weak rotation and small horizontal temperature gradients. Here, quasi-stationary equatorial planetary waves forced by the latent heat release from deep convection play a key role in the large-scale atmospheric circulation. Equatorial planetary waves are readily observed in the climatological-mean tropical circulation and are dominated by 1) an equatorially
1. Introduction Occurring in ∼50% of boreal winters, an enhancement of quasi-stationary planetary waves of zonal wavenumbers 1 and 2 can result in sudden stratospheric warmings (SSWs) (e.g., Butler et al. 2015 ). Upon dissipation, these waves strongly decelerate the stratospheric flow, inducing an overturning mean meridional circulation that adiabatically warms the polar region. The anomalous polar warming causes the stratopause to descend below its climatological altitude ( Matsuno 1971
1. Introduction Occurring in ∼50% of boreal winters, an enhancement of quasi-stationary planetary waves of zonal wavenumbers 1 and 2 can result in sudden stratospheric warmings (SSWs) (e.g., Butler et al. 2015 ). Upon dissipation, these waves strongly decelerate the stratospheric flow, inducing an overturning mean meridional circulation that adiabatically warms the polar region. The anomalous polar warming causes the stratopause to descend below its climatological altitude ( Matsuno 1971
possible cause of the instability is planetary wave (PW) forcing (PWF) (e.g., Baldwin and Holton 1988 ; Geer et al. 2013 ). More recently, the role of gravity wave (GW) forcing (GWF) 1 in the formation of the unstable condition is also a subject of focus (e.g., McLandress and McFarlane 1993 ; Norton and Thuburn 1996 ; Watanabe et al. 2009 ; Ern et al. 2011 ). It is well known that GWF in the upper mesosphere is important as a driving force of the residual mean circulation from the summer
possible cause of the instability is planetary wave (PW) forcing (PWF) (e.g., Baldwin and Holton 1988 ; Geer et al. 2013 ). More recently, the role of gravity wave (GW) forcing (GWF) 1 in the formation of the unstable condition is also a subject of focus (e.g., McLandress and McFarlane 1993 ; Norton and Thuburn 1996 ; Watanabe et al. 2009 ; Ern et al. 2011 ). It is well known that GWF in the upper mesosphere is important as a driving force of the residual mean circulation from the summer
, including a detailed comparison with previous approaches and an overview of the climatological wavenumber–frequency spectra in the extratropics. To investigate planetary wave interference effects, we will compare the structure of the standing waves and the climatological wave field. Last, we will compute the vertical and time-lagged coherences of the standing and traveling waves at selected Northern Hemisphere extratropical locations using correlation-coherence analysis ( Randel 1987 ). Section 4 will
, including a detailed comparison with previous approaches and an overview of the climatological wavenumber–frequency spectra in the extratropics. To investigate planetary wave interference effects, we will compare the structure of the standing waves and the climatological wave field. Last, we will compute the vertical and time-lagged coherences of the standing and traveling waves at selected Northern Hemisphere extratropical locations using correlation-coherence analysis ( Randel 1987 ). Section 4 will
1. Introduction Atmospheric waves play a central role in the middle atmospheric circulation. Planetary-scale Rossby waves (PWs) arising from large-scale topography and the land–sea thermal contrast predominate stratospheric phenomena, whereas in the upper stratosphere and mesosphere, smaller-scale gravity waves (GWs) forced by small-scale topography, convection, and jet/front systems play a key role ( Achatz et al. 2024 ; Andrews et al. 1987 ; Kim et al. 2003 ). While the relative
1. Introduction Atmospheric waves play a central role in the middle atmospheric circulation. Planetary-scale Rossby waves (PWs) arising from large-scale topography and the land–sea thermal contrast predominate stratospheric phenomena, whereas in the upper stratosphere and mesosphere, smaller-scale gravity waves (GWs) forced by small-scale topography, convection, and jet/front systems play a key role ( Achatz et al. 2024 ; Andrews et al. 1987 ; Kim et al. 2003 ). While the relative
1. Introduction A stratospheric sudden warming (SSW) is a typical manifestation of troposphere–stratosphere interaction in winter (e.g., Charney and Drazin 1961 ; Charlton and Polvani 2007 ). Since the first dynamical model of SSW was established by Matsuno (1971) , subsequent studies have suggested that the process of SSW is closely related to the upward propagation of planetary waves (PWs), especially waves 1 and 2, from the troposphere to the stratosphere (e.g., Nishii et al. 2011
1. Introduction A stratospheric sudden warming (SSW) is a typical manifestation of troposphere–stratosphere interaction in winter (e.g., Charney and Drazin 1961 ; Charlton and Polvani 2007 ). Since the first dynamical model of SSW was established by Matsuno (1971) , subsequent studies have suggested that the process of SSW is closely related to the upward propagation of planetary waves (PWs), especially waves 1 and 2, from the troposphere to the stratosphere (e.g., Nishii et al. 2011
is eddy dominated, whereas during winter the flow is closer to angular momentum conserving. In a zonal-mean framework, the monsoon–anticyclone system can be considered as a planetary-scale Rossby wave driven by land–ocean (east–west) heating asymmetries [following Gill (1980) ] with associated planetary-scale wave transport. Lorenz (1969, 1984) made a clear distinction between the “ideal Hadley circulation,” which is zonally symmetric and the “modified Hadley circulation,” which includes east
is eddy dominated, whereas during winter the flow is closer to angular momentum conserving. In a zonal-mean framework, the monsoon–anticyclone system can be considered as a planetary-scale Rossby wave driven by land–ocean (east–west) heating asymmetries [following Gill (1980) ] with associated planetary-scale wave transport. Lorenz (1969, 1984) made a clear distinction between the “ideal Hadley circulation,” which is zonally symmetric and the “modified Hadley circulation,” which includes east
upper levels ( Rivière 2009 ). On the contrary, the planetary, low-frequency waves act to hasten the short-term decay of the zonal wind anomalies during the first week following their peak ( Feldstein and Lee 1998 ; Watterson 2002 ). By analyzing observational datasets, Lorenz and Hartmann (2003) showed that the jet acts as a waveguide for these waves; so they propagate into the jet and remove momentum from it. This general behavior of planetary waves is well reproduced in simple models ( O
upper levels ( Rivière 2009 ). On the contrary, the planetary, low-frequency waves act to hasten the short-term decay of the zonal wind anomalies during the first week following their peak ( Feldstein and Lee 1998 ; Watterson 2002 ). By analyzing observational datasets, Lorenz and Hartmann (2003) showed that the jet acts as a waveguide for these waves; so they propagate into the jet and remove momentum from it. This general behavior of planetary waves is well reproduced in simple models ( O
their ability to transport heat poleward. We find that the poleward sensible heat transport is 1.17 PW throughout the entire column—a value in good agreement with previous studies ( Peixoto and Oort 1992 ; Trenberth and Stepaniak 2003 ). Partitioning the transport between tropospheric (below 300 hPa) and stratospheric contributions, we find transports of 0.46 and 0.71 PW, respectively. Insomuch as there are mechanisms that excite transient planetary-scale waves that act to amplify through
their ability to transport heat poleward. We find that the poleward sensible heat transport is 1.17 PW throughout the entire column—a value in good agreement with previous studies ( Peixoto and Oort 1992 ; Trenberth and Stepaniak 2003 ). Partitioning the transport between tropospheric (below 300 hPa) and stratospheric contributions, we find transports of 0.46 and 0.71 PW, respectively. Insomuch as there are mechanisms that excite transient planetary-scale waves that act to amplify through
