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1. Introduction The stationary wave field, which is the zonally asymmetric part of the time mean flow, is a principal field to explain in the atmospheric general circulation. It plays a significant role in the eddy-driven zonal mean circulation and is key to understanding climate variability and change on regional scales (e.g., Held et al. 2002 , and references therein). Stationary wave theory has progressed from a focus on the simple linear response to thermal and orographic forcing (e
1. Introduction The stationary wave field, which is the zonally asymmetric part of the time mean flow, is a principal field to explain in the atmospheric general circulation. It plays a significant role in the eddy-driven zonal mean circulation and is key to understanding climate variability and change on regional scales (e.g., Held et al. 2002 , and references therein). Stationary wave theory has progressed from a focus on the simple linear response to thermal and orographic forcing (e
friction was included to balance streamfunction tendencies induced by vorticity advection and vortex stretching. More recently, depicting these monsoon circulations with summer stationary waves, the maintenance mechanisms of these monsoon highs were illustrated with differential heating through the east–west circulation and the interaction between the east–west circulation and these highs through the Sverdrup relationship ( Chen 2003 , 2005a ). In the lower troposphere, continental thermal lows of
friction was included to balance streamfunction tendencies induced by vorticity advection and vortex stretching. More recently, depicting these monsoon circulations with summer stationary waves, the maintenance mechanisms of these monsoon highs were illustrated with differential heating through the east–west circulation and the interaction between the east–west circulation and these highs through the Sverdrup relationship ( Chen 2003 , 2005a ). In the lower troposphere, continental thermal lows of
1. Introduction Although the solar forcing at the top of the atmosphere is zonally symmetric when averaged over a day or longer, the climate of Earth is decidedly not zonally symmetric. These zonal asymmetries, or stationary waves, are forced by asymmetries in the lower boundary, such as the land–ocean distribution and orography. The land–ocean distribution directly impacts the distribution of surface temperature and moisture, while mountains directly impact the atmospheric flow (e.g., Held et
1. Introduction Although the solar forcing at the top of the atmosphere is zonally symmetric when averaged over a day or longer, the climate of Earth is decidedly not zonally symmetric. These zonal asymmetries, or stationary waves, are forced by asymmetries in the lower boundary, such as the land–ocean distribution and orography. The land–ocean distribution directly impacts the distribution of surface temperature and moisture, while mountains directly impact the atmospheric flow (e.g., Held et
1. Introduction The Northern Hemispheric climatological stationary wave is a primarily low zonal wavenumber feature in the flow that is likely the result of a complex interplay between thermal and orographic forcing in both the tropics and extratropics (e.g., Held et al. 2002 ). Recent studies have shown that important insights about the dynamics of the Northern Hemispheric circulation can be gleaned by investigating the role of transient eddy interference with the climatological stationary
1. Introduction The Northern Hemispheric climatological stationary wave is a primarily low zonal wavenumber feature in the flow that is likely the result of a complex interplay between thermal and orographic forcing in both the tropics and extratropics (e.g., Held et al. 2002 ). Recent studies have shown that important insights about the dynamics of the Northern Hemispheric circulation can be gleaned by investigating the role of transient eddy interference with the climatological stationary
1. Introduction The conventional linear theory of trapped lee waves assumes that mountains excite free modes of oscillations ( Scorer 1949 ). These modes are composed of stationary gravity waves that are entirely reflected downward at a turning altitude located in the midtroposphere and entirely reflected upward at the ground. Although this theory is largely supported by observations, there are situations where the atmospheric conditions aloft are favorable for the low-level trapping of gravity
1. Introduction The conventional linear theory of trapped lee waves assumes that mountains excite free modes of oscillations ( Scorer 1949 ). These modes are composed of stationary gravity waves that are entirely reflected downward at a turning altitude located in the midtroposphere and entirely reflected upward at the ground. Although this theory is largely supported by observations, there are situations where the atmospheric conditions aloft are favorable for the low-level trapping of gravity
occurs sporadically, when wave packets are emitted during a finite period of time. However, in a recent numerical study of the small-amplitude spiral wave patterns caused by the IGWs spreading away from the vortical flow in the baroclinic dipole ( Viúdez 2006 ) it was noticed that there is a wave packet, of large vertical velocity, that remains stationary, trapped in the frontal part of the translating dipole. The characteristics of this wave packet, named here the frontal wave packet because it
occurs sporadically, when wave packets are emitted during a finite period of time. However, in a recent numerical study of the small-amplitude spiral wave patterns caused by the IGWs spreading away from the vortical flow in the baroclinic dipole ( Viúdez 2006 ) it was noticed that there is a wave packet, of large vertical velocity, that remains stationary, trapped in the frontal part of the translating dipole. The characteristics of this wave packet, named here the frontal wave packet because it
. 2013 ) patterns in convective activity, the “silk road” pattern in the 200-hPa meridional velocity ( Lu et al. 2002 ; Enomoto et al. 2003 ), and the circumglobal teleconnection (CGT) pattern ( Ding and Wang 2005 ; Ding et al. 2011 ). Teleconnection patterns are thought of as stationary waves emanating from a source region. These patterns, in general, are either zonally or meridionally oriented. The zonally oriented patterns, such as the Eurasian, the silk road, and the CGT patterns, develop along
. 2013 ) patterns in convective activity, the “silk road” pattern in the 200-hPa meridional velocity ( Lu et al. 2002 ; Enomoto et al. 2003 ), and the circumglobal teleconnection (CGT) pattern ( Ding and Wang 2005 ; Ding et al. 2011 ). Teleconnection patterns are thought of as stationary waves emanating from a source region. These patterns, in general, are either zonally or meridionally oriented. The zonally oriented patterns, such as the Eurasian, the silk road, and the CGT patterns, develop along
1. Introduction and objectives Stationary waves are planetary-scale, zonally asymmetric circulations that are relatively stable on seasonal time scales ( Nigam and DeWeaver 2003 ). In boreal summer, stationary waves with a baroclinic vertical structure are primarily found in the northern tropics and subtropics, with the largest amplitude between 15° and 45°N ( Wills et al. 2019 ; Fig. 1b ). Two lower-tropospheric anticyclones underneath the upper-level troughs are present in the North
1. Introduction and objectives Stationary waves are planetary-scale, zonally asymmetric circulations that are relatively stable on seasonal time scales ( Nigam and DeWeaver 2003 ). In boreal summer, stationary waves with a baroclinic vertical structure are primarily found in the northern tropics and subtropics, with the largest amplitude between 15° and 45°N ( Wills et al. 2019 ; Fig. 1b ). Two lower-tropospheric anticyclones underneath the upper-level troughs are present in the North
. Because of its considerable spatiotemporal variation, and the striking geographical differences between the Northern Hemisphere (NH) landmasses, the influence of snow on atmospheric circulation is an area of ongoing research. In particular, the nature of the large-scale stationary wave response to anomalous North American (NA) snow cover and its associated mechanisms remains largely unexplored. Physically based snow–climate teleconnections have been described more often for Eurasia than for NA. This
. Because of its considerable spatiotemporal variation, and the striking geographical differences between the Northern Hemisphere (NH) landmasses, the influence of snow on atmospheric circulation is an area of ongoing research. In particular, the nature of the large-scale stationary wave response to anomalous North American (NA) snow cover and its associated mechanisms remains largely unexplored. Physically based snow–climate teleconnections have been described more often for Eurasia than for NA. This
eddy streamfunction during 1979–2017 (shading) and the 300-hPa climatological stationary wave (contours). The contour interval is 2.5 × 10 6 m 2 s −1 ; negative values are dashed, and the zero value is omitted. (b) The 300-hPa eddy streamfunction anomaly composite for destructive SWI at lag day 0 (shading). The contours are as in (a). The green-outlined box indicates the projection domain of SWI. (c) Lagged composite of SWI against positive events of TI (blue line), and lagged composite of TI
eddy streamfunction during 1979–2017 (shading) and the 300-hPa climatological stationary wave (contours). The contour interval is 2.5 × 10 6 m 2 s −1 ; negative values are dashed, and the zero value is omitted. (b) The 300-hPa eddy streamfunction anomaly composite for destructive SWI at lag day 0 (shading). The contours are as in (a). The green-outlined box indicates the projection domain of SWI. (c) Lagged composite of SWI against positive events of TI (blue line), and lagged composite of TI
