Multiple “Gust Layers” Observed in the Middle Stratosphere

Yamanaka, Manabu D.; Tanaka, Hiroshi

doi:10.1007/978-94-009-6390-0_7

Cited by 15 publications

(4 citation statements)

References 32 publications

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“…When the wave source is remote from the Jones' critical level, conventional mechanism based on non-inertial gravity wave is likely to work since the major part of wave would have damped out till the wave reaches the Jones' critical level. Some preliminary prospects on these problems in the actual stratosphere are presented elsewhere (Yamanaka and Tanaka, 1984).…”

Section: Formation Of Turbulence Layersmentioning

confidence: 99%

Propagation and Breakdown of Internal Inertio-Gravity Waves Near Critical Levels in the Middle Atmosphere

Yamanaka

Tanaka

1984

Journal of the Meteorological Society of Japan

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Behaviors of internal inertio-gravity waves (IIGW) near Jones' critical levels are studied theoretically in view of a possible origin of turbulence layers in the middle atmosphere. The inertial effect associated with the earth's rotation cannot be neglected when time constant of the wave is large. Assuming that the vertical shear and Coriolis factor are constant, exact solutions of IIGW are obtained from inviscid and linear equations. The asymptotic expressions are derived by means of the Liouville-Green method developed by Olver (1974) which leads to an exact dispersion relation near the critical levels. Two important features about critical level problem of IIGW are found from the dispersion relation: valve effect across the Jones' critical levels in somewhat different sense from Grimshaw (1975, 1980), and presence of a pair of turning levels between both Jones' critical levels. Coupling these features, we predict that IIGW is absorbed or reflected by the Jones' critical levels depending on the direction of wave-front. The absorption rate and the thickness of turbulence layer produced by critical level breakdown increase as the wave-fronts tend to direct to the zonal direction, on the other hand IIGW is substantially reflected when they direct to the meridional direction. With increase of basic Richardson number the turning levels approach asymptotically the critical levels, so that turbulence layers inside the critical levels become thinner than those outside them. These features vanish in the case of non-inertial gravity waves. The relation between IIGW and turbulence layers is calculated to compare with the turbulence layers observed in the stratosphere and to have information on IIGW's propagating upwards to the mesosphere and the thermosphere. In general, thickness of the turbulence layers associated with IIGW's is thinner than that associated with non-inertial gravity waves for common mesoscale wavelength domain. * Graduate student of Nagoya University.

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Section: Formation Of Turbulence Layersmentioning

confidence: 99%

Propagation and Breakdown of Internal Inertio-Gravity Waves Near Critical Levels in the Middle Atmosphere

Yamanaka

Tanaka

1984

Journal of the Meteorological Society of Japan

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“…On the other hand the ageostrophic component introduced in the flow by a hypothetical nocturnal jet mechanism may not be higher than the geostrophic wind variation over a turbulent layer width. As this width is, at most, a few hundred meters [Barat, 1982b;Yamanaka and Tanaka, 1984] in the middle stratosphere, we may not expect resulting inertial components as important as those observed.…”

Section: Discussionmentioning

confidence: 87%

Observational evidence of an inertial wind structure in the stratosphere

Sidi¹,

Barat²

1986

J. Geophys. Res.

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A nearly inertial evolution of the relative velocities measured by differential sounding (Barat, 1982a) has been observed along a balloon flight in the 26–30 km altitude range. The vertical structure of the flow appears to be a stack of layers a few hundred meters wide undergoing independent, nearly inertial oscillations added to the mean flow, the transitions between adjacent layers being characterized by abrupt rotations of the horizontal wind. We show that the stability of such a structure, despite the very high wind shears encountered within transitions, is consistent with the very weak turbulent viscosity coefficient independently estimated. As a tentative interpretation of our observations we suggest that they are related to the dissipation of an internal gravity wave near a critical level.

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“…Concerning only the upward decrease in the tropopause-lower stratosphere region, we may imagine a situation similar to the monochromatic gravity wave critical level problem (see, e.g., Fritts, 1984;Yamanaka and Tanaka, 1984). Namely, for waves with zero phase velocity (such as mountain waves) propagating upward, the (local) vertical wavelength must decrease toward the critical level, which is located at where u = 0.…”

Section: Discussion In Comparison With Mean Wind Profilementioning

confidence: 99%

Application of Two-Dimensional Wavelet Analysis to Wind Disturbances Observed with MU Radar in the Lower Stratosphere and Troposphere

Shimomai

Yamanaka

Fukao

1997

J. geomagn. geoelec

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Orthonormal wavelet analysis is applied for the first time to two-dimensional (time and height) data obtained from three-week continuous MU radar observations in June-July, 1991. It is confirmed that monochromatic wave structures are generally localized both in time and in altitude. We find the dominant temporal scale of wave activity in this case study is 2-4 days. The dominant vertical wavelength seems to decrease from -4 km to -1 km, upwards through the tropopause-lower stratosphere region, which is almost independent of temporal scales in the 1-4 day range.

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Multiple “Gust Layers” Observed in the Middle Stratosphere

Cited by 15 publications

References 32 publications

Propagation and Breakdown of Internal Inertio-Gravity Waves Near Critical Levels in the Middle Atmosphere

Propagation and Breakdown of Internal Inertio-Gravity Waves Near Critical Levels in the Middle Atmosphere

Observational evidence of an inertial wind structure in the stratosphere

Application of Two-Dimensional Wavelet Analysis to Wind Disturbances Observed with MU Radar in the Lower Stratosphere and Troposphere

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