Lower‐stratospheric Rossby wave trains in the southern hemisphere: A case‐study for late winter of 1997

Nishii, Kazuaki; Nakamura, Hisashi

doi:10.1256/qj.02.156

Cited by 23 publications

(15 citation statements)

References 35 publications

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“…This important point, which can easily be seen from the extended CD, could not be gleaned from the case-studies of either Canziani and Legnani (2003) or Nishii and Nakamura (2004), both of whom confirmed the existence of preferred longitudes for the local vertical propagation of wave activity in zonally non-uniform flow.…”

Section: Ray Tracingmentioning

confidence: 93%

“…A more complete picture requires consideration of both the zonal and meridional wind components of the background flow. Nishii and Nakamura (2004) applied a (local) threedimensional refractive index and a wave activity flux vector, both of which hinge on a local coordinate rotation and the assumption of a weakly forced, slowly varying background flow, to examine the vertical propagation of sub-monthly wave anomalies during the 1997 Southern Hemisphere winter. They found that the localized, vertically propagating wave activity that originated in the troposphere and penetrated into the lower stratosphere was sensitive to the three-dimensional structure of the local vertical waveguide and the location of the wave source within the waveguide.…”

Section: Introductionmentioning

confidence: 99%

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Troposphere–stratosphere communication through local vertical waveguides

Nathan

Hodyss

2010

Quart J Royal Meteoro Soc

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The effects of zonally non-uniform background flow on the three-dimensional propagation of extratropical Rossby waves are examined using the WKB (Wentzel-Kramers-Brillouin) formalism. Emphasis is placed on the vertical propagation of wave activity. An extended Charney-Drazin (CD) condition that is valid for zonally non-uniform background flow is derived. The extended CD condition shows that local vertical propagation (trapping) is possible for wave scales for which the traditional CD condition predicts trapping (propagation). Local vertical propagation is shown to be strongly dependent on the phasing of the wave source relative to the background flow. Specifically, in zonally non-uniform background flow, vertical propagation is confined to local vertical waveguides whose formation is controlled by the orientation of the background wind relative to the wave fronts. Within the waveguide, vertical propagation is optimized when the disturbance wind field is parallel to the background potential vorticity gradient. As the wave packets move from the tropospheric source into the stratosphere they expand in zonal scale. The implications of these results to stratospheric sudden warmings are discussed.

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Section: Ray Tracingmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Troposphere–stratosphere communication through local vertical waveguides

Nathan

Hodyss

2010

Quart J Royal Meteoro Soc

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“…While wave-mean flow interaction is usually small in the SH winter (Thompson and Wallace 2000), there are a few notable exceptions. In 1997, the stratospheric polar vortex was repeatedly disturbed by waves propagating upward from tropospheric quasi-stationary anomalies including blocking highs (Nishii and Nakamura 2004). In 2002, several wave events originating from the midlatitude troposphere disturbed the winter polar vortex (Newman and Nash 2005), which finally resulted in the prominent split of the Antarctic ozone hole (Varotsos 2002).…”

Section: Introductionmentioning

confidence: 99%

Missing Stratospheric Ozone Decrease at Southern Hemisphere Middle Latitudes after Mt. Pinatubo: A Dynamical Perspective

Poberaj

Staehelin

Brunner

2011

Journal of the Atmospheric Sciences

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Although large total ozone decreases occurred in the Northern Hemisphere extratropics in the years after the volcanic eruption of Mt. Pinatubo that are generally attributed to the eruption, comparable decreases did not emerge in the Southern Hemisphere. To study this missing decrease, a multiple linear regression was applied to the Chemical and Dynamical Influences on Decadal Ozone Change (CANDIDOZ) Assimilated Three-Dimensional Ozone (CATO) dataset including the solar cycle, the quasi-biennial oscillation (QBO), the effect of volcanic eruptions, the lower stratospheric (LS) Eliassen-Palm (EP) flux to describe the Brewer-Dobson circulation, and stratospheric chlorine increase as explanatory variables. Volcanically induced chemical ozone depletion was overcompensated by the QBO and by a pronounced EP flux anomaly. Using NCEP-NCAR reanalysis data, it is found that the anomalous EP flux was caused by several significant stratospheric wave events (SWEs) from September-November 1991 through 1992 that, together with aerosol heating, led to a significantly enhanced Brewer-Dobson circulation and more ozone transport from the tropics to the extratropics. The onset of the volcanic ozone loss was shifted into 1992 and the strength of the signal was reduced. Most SWEs can be traced back to the troposphere and a significant fraction was associated with atmospheric blocking patterns preceding the SWEs. In 1991/92, the southern annular mode was in a negative phase and El Niñ o-Southern Oscillation in a warm phase. It is suggested that this constellation favored a flow preconditioning toward quasi-stationary features including blocking, which was significantly enhanced in 1991/92. During June-August 1992, blocking occurred preferably over the southeastern Pacific, pointing to a major ENSO influence on LS wave activity.

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“…Nishii and Nakamura (2004b) found that a Rossby wave train propagating upwards from a blocking flow configuration over the South Atlantic contributed to the breakdown of the SH polar vortex in late September 2002 that led to the collapse of the ozone hole. Nishii and Nakamura (2004a; hereafter referred to as NN04) analysed dynamical characteristics of submonthly geopotential height fluctuations observed in the SH lower stratosphere during late winter and early spring of 1997. They showed that those fluctuations were often associated with zonally confined Rossby wave trains that had originated from quasi-stationary tropospheric anomalies.…”

Section: Introductionmentioning

confidence: 99%

Upward and downward injection of Rossby wave activity across the tropopause: A new aspect of the troposphere–stratosphere dynamical linkage

Nishii

Nakamura

2005

Quart J Royal Meteoro Soc

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SUMMARYPropagation of zonally confined Rossby wave activity between the troposphere and lower stratosphere of the southern hemisphere during austral winter and spring of 1997 is studied, by using a wave-activity flux and refractive index, both defined for stationary Rossby waves on a zonally asymmetric time-mean flow. A particular event of large-scale quasi-stationary cyclogenesis in the troposphere is discussed, to which downward waveactivity injection from anticyclonic anomalies upstream that had developed in the exit region of the lowerstratospheric polar-night jet (PNJ) contributed substantially. Consistent with that downward injection, phase lines of observed stream-function anomalies exhibited a distinct eastward tilt with height. The development of the anticyclonic anomalies occurred at the leading edge of a quasi-stationary Rossby wave train propagating along the PNJ, that had originated from a tropospheric blocking ridge farther upstream. Though less common than upward wave-activity injection across the tropopause, similar events of downward wave-activity injection occurred several times during that season, primarily in the regions south of Australia and over the central South Pacific, over each of which the PNJ exit overlapped with a tropospheric subpolar jet to form a vertical waveguide locally. It is argued that the downward wave-activity propagation is essentially due to refraction in the vertically sheared westerlies, and the zonal asymmetries in the time-mean flow are a likely factor for the observed geographical preference of the downward wave-activity injection.

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Lower‐stratospheric Rossby wave trains in the southern hemisphere: A case‐study for late winter of 1997

Cited by 23 publications

References 35 publications

Troposphere–stratosphere communication through local vertical waveguides

Troposphere–stratosphere communication through local vertical waveguides

Missing Stratospheric Ozone Decrease at Southern Hemisphere Middle Latitudes after Mt. Pinatubo: A Dynamical Perspective

Upward and downward injection of Rossby wave activity across the tropopause: A new aspect of the troposphere–stratosphere dynamical linkage

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