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1156JOURNAL OF THE ATMOSPHERIC SCIENCESVOL. 53, No. 8Longitudinal Variations in Mesospheric Winds: Evidence for Gravity Wave Filtering by Planetary WavesAtmospheric Chemistry Division, National Center for Atmospheric Research, * Boulder, Colorado (Manuscript received 23 June 1995, in final form 16 October 1995)ABSTRACT Mesospheric horizontal wind data from the High Resolution Doppler Imager (HRDI) satellite instrument areused to investigate the longitudinal variation of nontidal
1156JOURNAL OF THE ATMOSPHERIC SCIENCESVOL. 53, No. 8Longitudinal Variations in Mesospheric Winds: Evidence for Gravity Wave Filtering by Planetary WavesAtmospheric Chemistry Division, National Center for Atmospheric Research, * Boulder, Colorado (Manuscript received 23 June 1995, in final form 16 October 1995)ABSTRACT Mesospheric horizontal wind data from the High Resolution Doppler Imager (HRDI) satellite instrument areused to investigate the longitudinal variation of nontidal
VOL. 44, NO. 19 JOURNAL OF THE ATMOSPHERIC SCIENCES I OCTOBER 1987Vacillations Induced by Interference of Stationary and Traveling Planetary Waves MURRY L. SALBY*Department of Astrophysical, Planetary, and Atmospheric Sciences, University of Colorado, Boulder, CO 80309 ROLANDO R. GARCIA*National Center for Atmospheric Research,** Boulder, CO 80307(Manuscript received 6 October 1986, in final
VOL. 44, NO. 19 JOURNAL OF THE ATMOSPHERIC SCIENCES I OCTOBER 1987Vacillations Induced by Interference of Stationary and Traveling Planetary Waves MURRY L. SALBY*Department of Astrophysical, Planetary, and Atmospheric Sciences, University of Colorado, Boulder, CO 80309 ROLANDO R. GARCIA*National Center for Atmospheric Research,** Boulder, CO 80307(Manuscript received 6 October 1986, in final
1966 JOURNAL OF THE ATMOSPHERIC SCIENCES VOL. 50, No. 13Interactions between Orographic Gravity Wave Drag and Forced Stationary Planetary Waves in the Winter Northern Hemisphere Middle Atmosphere C. Mc LANDRESSInstitute for Space and Terrestrial Science, North York, Ontario, Canada N. A. MCFARLANECanadian Climate Centre, Downsview, Ontario, Canada(Manuscript received 2 December
1966 JOURNAL OF THE ATMOSPHERIC SCIENCES VOL. 50, No. 13Interactions between Orographic Gravity Wave Drag and Forced Stationary Planetary Waves in the Winter Northern Hemisphere Middle Atmosphere C. Mc LANDRESSInstitute for Space and Terrestrial Science, North York, Ontario, Canada N. A. MCFARLANECanadian Climate Centre, Downsview, Ontario, Canada(Manuscript received 2 December
1. Introduction An outstanding question about the Madden–Julian Oscillation (MJO; Madden and Julian 1971 , 1972 ) is why the oscillation prefers a planetary zonal scale. There have been a number of theoretical studies aimed at addressing this scale selection issue. Chang (1977) proposed that the MJO can be represented by convectively driven equatorial Kelvin waves. However, the wave–conditional instability of second kind (CISK) mechanism prefers the most unstable growth at a shorter zonal
1. Introduction An outstanding question about the Madden–Julian Oscillation (MJO; Madden and Julian 1971 , 1972 ) is why the oscillation prefers a planetary zonal scale. There have been a number of theoretical studies aimed at addressing this scale selection issue. Chang (1977) proposed that the MJO can be represented by convectively driven equatorial Kelvin waves. However, the wave–conditional instability of second kind (CISK) mechanism prefers the most unstable growth at a shorter zonal
1. Introduction A regime in which jets, planetary-scale waves, and vortices coexist is commonly observed in the turbulence of planetary atmospheres, with the banded winds and embedded vortices of Jupiter and the Saturn North Polar vortex constituting familiar examples ( Vasavada and Showman 2005 ; Sánchez-Lavega et al. 2014 ). Planetary-scale waves in the jet stream and vortices, such as cutoff lows, are also commonly observed in Earth’s atmosphere. Conservation of energy and enstrophy in
1. Introduction A regime in which jets, planetary-scale waves, and vortices coexist is commonly observed in the turbulence of planetary atmospheres, with the banded winds and embedded vortices of Jupiter and the Saturn North Polar vortex constituting familiar examples ( Vasavada and Showman 2005 ; Sánchez-Lavega et al. 2014 ). Planetary-scale waves in the jet stream and vortices, such as cutoff lows, are also commonly observed in Earth’s atmosphere. Conservation of energy and enstrophy in
1989 ; Smith et al. 2003 ), and the Met Office (UKMO) Stratosphere–Mesosphere Model (SMM) ( Gray et al. 2003 ). The lower boundaries of these models are specified, either by reanalysis data or by idealized formulation, to account for planetary waves and tides. TIME-GCM extends from the stratosphere (∼30 km) to the upper thermosphere, and the vertical ranges of ROSE and SMM are 15–110 km and 16–80 km, respectively. Examples of the latter include the Middle Atmosphere Circulation Model at Kyushu
1989 ; Smith et al. 2003 ), and the Met Office (UKMO) Stratosphere–Mesosphere Model (SMM) ( Gray et al. 2003 ). The lower boundaries of these models are specified, either by reanalysis data or by idealized formulation, to account for planetary waves and tides. TIME-GCM extends from the stratosphere (∼30 km) to the upper thermosphere, and the vertical ranges of ROSE and SMM are 15–110 km and 16–80 km, respectively. Examples of the latter include the Middle Atmosphere Circulation Model at Kyushu
630 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUM-3The Secondary Flow near a Baroclinic Planetary Wave Critical Line MARK R. SCHOEBERLGeophysical and Plasma Dynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375(Manuscript received 13 March 1980, in final form 18 November 1980) ABSTRACT The wave-mean flow interaction has
630 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUM-3The Secondary Flow near a Baroclinic Planetary Wave Critical Line MARK R. SCHOEBERLGeophysical and Plasma Dynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375(Manuscript received 13 March 1980, in final form 18 November 1980) ABSTRACT The wave-mean flow interaction has
not reach as far in Fig. 15a as in Fig. 14c . If instead of Fig. 14c , we look at the same field generated from the same simulation of forcing amplitude 0.9, 6 days earlier, or on day 20 shown in Fig. 15b , the wave train looks almost the same as in Fig. 15a , for forcing amplitude 0.6 on day 26. Other forcing amplitudes were also considered and they support the conclusion that given enough forcing, planetary waves will be reflected out of the low-latitude wave-breaking region. The greater
not reach as far in Fig. 15a as in Fig. 14c . If instead of Fig. 14c , we look at the same field generated from the same simulation of forcing amplitude 0.9, 6 days earlier, or on day 20 shown in Fig. 15b , the wave train looks almost the same as in Fig. 15a , for forcing amplitude 0.6 on day 26. Other forcing amplitudes were also considered and they support the conclusion that given enough forcing, planetary waves will be reflected out of the low-latitude wave-breaking region. The greater
eastern Atlantic and Europe, anticyclonic wave breaking occurs ( Figs. 4c,d ) resulting in a blocking anticyclone through amplification of the ambient planetary ridge ( Fig. 2a ). The polar air advected equatorward and westward in the wave breaking can lead to a cutoff low to the south. Another picture of this evolution is given by Fig. 5 , which presents the evolution in terms of the anomalies in θ on the 2-PVU surface for the same set of days. Four days before onset ( Fig. 5a ) it is seen that
eastern Atlantic and Europe, anticyclonic wave breaking occurs ( Figs. 4c,d ) resulting in a blocking anticyclone through amplification of the ambient planetary ridge ( Fig. 2a ). The polar air advected equatorward and westward in the wave breaking can lead to a cutoff low to the south. Another picture of this evolution is given by Fig. 5 , which presents the evolution in terms of the anomalies in θ on the 2-PVU surface for the same set of days. Four days before onset ( Fig. 5a ) it is seen that
. (2009) , support the idea that a so-called stratospheric pathway is required to transform ENSO teleconnections from a regional phenomenon affecting mainly North America into NAM-like events with hemispheric extent. An increasing body of research has shown that seasonal variations in the NAM depend on the phasing (linear interference) of extratropical planetary waves ( Nishii et al. 2011 ; Garfinkel and Hartmann 2008 ; Smith et al. 2010 ; FK13 , FK11 ; Kim et al. 2014 ). Briefly, all of these
. (2009) , support the idea that a so-called stratospheric pathway is required to transform ENSO teleconnections from a regional phenomenon affecting mainly North America into NAM-like events with hemispheric extent. An increasing body of research has shown that seasonal variations in the NAM depend on the phasing (linear interference) of extratropical planetary waves ( Nishii et al. 2011 ; Garfinkel and Hartmann 2008 ; Smith et al. 2010 ; FK13 , FK11 ; Kim et al. 2014 ). Briefly, all of these
