Some aspects of linear lee wave theory for the stratosphere

Berkshire, Frank; Warren, F. W. G.

doi:10.1002/qj.49709640707

Cited by 11 publications

(4 citation statements)

References 6 publications

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“…As it has been already mentioned, for sufficiently low velocities (U 0 ≤30 ms −1 ), the major differences between the hydrostatic and non-hydrostatic solutions take place in the vicinity of the quasi-resonant peaks, where, along with the hydrostatic component of the solution, the amplification of the short, partially trapped waves takes place (Berkshire and Warren, 1970). One can see from Figs.…”

Section: Three-layer Solutionmentioning

confidence: 51%

“…It was found that partial reflection of wave energy by individual layers with different static stability and/or wind velocity can produce a strong influence on the flow field in the free atmosphere (Scorer, 1949;Blumen, 1965;Eliassen and Palm, 1961;Berkshire and Warren, 1970). Some aspects of this problem were considered in many of investigations (see reviews by Queney et al, 1960;Kozhevnikov, 1970;Smith, 1979;Röttger, 2000), principally in the framework of linear models permitting one to account for actual really observed vertical distributions of atmospheric characteristics, including those at large altitudes (Palm and Foldvik, 1960;Berkshire, 1975).…”

Section: Introductionmentioning

confidence: 99%

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On the role of the stratosphere in the process of overflow of mesoscale mountains

Moiseenko

2005

Ann. Geophys.

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Abstract.A 2-D, two-and three-layer stratified airflow over a mountain of arbitrary shape is considered on the assumptions that upstream wind velocity and static stability within each layer are constant (Long's model). The stratosphere is simulated by an infinitely deep upper layer with enhanced static stability.The analytical solution for the stream function, as well as first (linear) and second order approximations to the wave drag, are obtained in hydrostatic limit N 1 L/U 0 →∞, where N 1 is the Brunt-Väsälä frequency in the troposphere, L is a characteristic length of the obstacle, and U 0 is upstream velocity. The results of numerical computations show the principal role of long waves in the process of interaction between the model layers for a typical mesoscale mountains for which the hydrostatic approximation proves valid in a wide range of flow parameters, in accordance with the earlier conclusions of Klemp and Lilly (1975). Partial reflection of wave energy from the tropopause produces strong influence on the value of wave drag for typical middle and upper tropospheric lapse rates, leading to a quasi-periodic dependance of wave drag on a reduced frequency k=N 1H /πU 0 (H is tropopause height) in the troposphere. The flow seems to be statically unstable for k≥2 for sufficiently large obstacles (whose height exceeds 1 km). In this case, vast regions of rotor motions and strong turbulence are predicted from model calculations in the middle troposphere and the lower stratosphere. The model calculations also point to a testify for possible important role of nonlinear effects associated with finite height of the mountain on the conditions of wave drag amplification in the process of overflow of real mountains.

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Section: Three-layer Solutionmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

On the role of the stratosphere in the process of overflow of mesoscale mountains

Moiseenko

2005

Ann. Geophys.

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“…The tropopause acting as a ''leaky'' lid can be important for lee waves in sheared flow (e.g., Keller 1994) and for propagating gravity waves generated by convection (Lane and Zhang 2011). As the troposphere 2 stratosphere stability difference becomes greater, less energy leaks through and the tropopause begins to act more like a rigid lid (e.g., Berkshire and Warren 1970). Stable layers functioning as reflective surfaces similar to rigid lids have also been noted in density current simulations (Xue 2002) and for elevated inversions in downslope windstorm simulations (e.g., Smith and Skyllingstad 2011).…”

Section: Introductionmentioning

confidence: 98%

Upstream-Propagating Wave Modes in Moist and Dry Flow over Topography

Keller

Rotunno

Steiner

et al. 2012

Journal of the Atmospheric Sciences

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Previous studies have observed upstream-propagating modes in two-dimensional numerical simulations of idealized flow over topography with moist, nearly neutral conditions in the troposphere, topped by a stable stratosphere. The generation and propagation mechanisms for these modes were attributed to localized and dramatic changes in stability induced by the desaturation of the flow impinging on the mountain. In the present paper it is shown that these modes are transient upstream-propagating gravity waves, which are a fundamental feature of both moist and dry flow over topography of a two-layer troposphere-stratosphere atmospheric profile impulsively started from rest. The mode selection and propagation speeds of these transient waves are highly dependent on the tropospheric stability, as well as the wind speed and tropopause depth. In the moist case these modes appear to propagate according to an effective static stability that is intermediate to the normal dry stability and the lower moist stability. Comparisons with the linear, timedependent, hydrostatic analytic solution show that these modes are similar to the transients observed in flow of a constant wind and stability layer over topography with a rigid upper boundary.

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“…In the last decade, interest has been shown in these evanescent modes produced by a long terrestrial mountain ridge, and attention has been directed toward a stratosphere-troposphere model in which the troposphere is divided into an upper and lower region with differing stabilities in each. This theory has been discussed by Berkshire and Warren [1970] and Berkshire [1975], while in Berkshire and Pickersgill [1978] this model is adapted to consider a troposphere with increasing or decreasing stability with height and a stably stratified stratosphere. Pirraglia [1976] has investigated the theory of trapped Martian lee waves produced by an isolated crater of diameter 100 km in the northern winter.…”

Section: Introductionmentioning

confidence: 99%

The formation of Martian lee waves generated by a crater

Pickersgill¹,

Hunt²

1979

J. Geophys. Res.

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The vertical wave displacement, generated by a Martian crater, propagating upward from a lower atmospheric layer into an upper layer is investigated in this paper. An examination is made of the leakage of this displacement into the upper Martian atmosphere (•20 km) for conditions where the atmospheric interface between the two layers is the level at which a discontinuity occurs, either in the stability profile or in the velocity profile. A comparison is made with the atmospheric conditions which exist when the stability and velocity profiles are continuous at all levels. Observed lee wave phenomena are compared with those predicted by this model. It is found that airflow in the upper layer depends critically on the atmospheric stability in the lower layer, the 'ship-wake' pattern predominates for a decrease in stability with height.

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Some aspects of linear lee wave theory for the stratosphere

Cited by 11 publications

References 6 publications

On the role of the stratosphere in the process of overflow of mesoscale mountains

On the role of the stratosphere in the process of overflow of mesoscale mountains

Upstream-Propagating Wave Modes in Moist and Dry Flow over Topography

The formation of Martian lee waves generated by a crater

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