Solitary Waves in the Atmosphere

Rottman, James W.; Einaudi, Franco

doi:10.1175/1520-0469(1993)050<2116:swita>2.0.co;2

Cited by 54 publications

(48 citation statements)

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“…This type of pressure change cannot determine the type of solitary wave because it does not depend on the type of solitary wave but rather on the depth of the wave duct in which the wave propagates, although the BDO type usually exhibits a pressure peak. The difference between the two types of the solitary waves appears in the profile of vertical velocity (Rottman and Einaudi, 1993). For the BDO type, the largest vertical displacement (an up-down motion) occurs at the top of the waveguide, whereas for the KdV type it occurs in the middle of the waveguide.…”

Section: The Solitary Wave and Its Ducting Mechanismmentioning

confidence: 99%

“…This figure shows that the atmosphere is nearly neutrally stratified from 150 m to 2000 m in altitude. Rottman and Einaudi (1993) indicated that the solitary wave can propagate in a nearly neutrally stratified atmosphere if there is a deep enough region of negative K 2 (or even small positive values of K 2 , where K is the Scorer parameter) above the wave. They also proposed that a layer of low N 2 , where N is the Brunt-Väisälä frequency, can also act as a reflector of the wave.…”

Section: The Solitary Wave and Its Ducting Mechanismmentioning

confidence: 99%

“…In the Boussinesq approximation, since the variation of the background density is negligible, only the first two terms in the equation are kept (Rottman and Einaudi, 1993). For the solution of (4), the Brunt-Väisälä frequency N can be derived from the profile of the virtual potential temperature (Fig.…”

Section: The Solitary Wave and Its Ducting Mechanismmentioning

confidence: 99%

“…In recent years, much progress has been made in the observation and understanding of atmospheric internal solitary waves generated from the gravity currents. Internal atmospheric solitary waves fall into two categories (Rottman and Einaudi, 1993;Rottman and Grimshaw, 2001). The first category is confined to the lower troposphere and is generated locally, while the second category fills the troposphere and is generated by large-scale processes such as geostrophic adjustment.…”

Section: Introductionmentioning

confidence: 99%

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An observational study of a shallow gravity current triggered by katabatic flow

Adachi

Clark²,

Hartten³

et al. 2004

Ann. Geophys.

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Abstract.Observations from a wind profiler and a meteorological tower are utilized to study the evolution of a gravity current that passed over the Meteorological Research Institute's (MRI) field site in Tsukuba, Japan. The gravity current was created by katabatic flow originating on the mountainous slopes west of the field site. The passage of the shallow current was marked by a pronounced pressure disturbance and was accompanied by vertical circulations seen in the tower and profiler data. Direct vertical-beam measurements are difficult, especially at low heights during highgradient events like density currents. In this study vertical velocities from the profiler are derived from the four oblique beams by use of the Minimizing the Variance of the Differences (MVD) method. The vertical velocities derived from the MVD method agree well with in situ vertical velocities measured by a sonic anemometer on the tower.The gravity current is analyzed with surface observations, the wind profiler/RASS and tower-mounted instruments. Observations from the profiler/RASS and the tower-mounted instruments illustrate the structure of the gravity current in both wind and temperature fields. The profiler data reveal that there were three regions of waves in the vertical velocity field: lee-type waves, a solitary wave and Kelvin-Helmholtz waves. The lee-type waves in the head region of the gravity current seem to have been generated by the gravity current acting as an obstacle to prefrontal flow. The solitary wave was formed from the elevated head of the gravity current that separated from the feeder flow. Profiler vertical-motion observations resolve this wave and enable us to classify it as a Benjamin-Davis-Ono (BDO) type solitary wave. The ducting mechanism that enabled the solitary wave to propagate is also revealed from the wind profiler/RASS measurements. The combination of high-resolution instruments at the MRI site allow us to develop a uniquely detailed picture of a shallow gravity current structure.

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Section: The Solitary Wave and Its Ducting Mechanismmentioning

confidence: 99%

Section: The Solitary Wave and Its Ducting Mechanismmentioning

confidence: 99%

Section: The Solitary Wave and Its Ducting Mechanismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An observational study of a shallow gravity current triggered by katabatic flow

Adachi

Clark²,

Hartten³

et al. 2004

Ann. Geophys.

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“…Scale analysis reveals that transcritical flow is likely to be ubiquitious in the ocean and atmosphere (e.g. Rottman & Einaudi 1993), and characteristic transcritical flow patterns have been distinguished in cloud photographs (Stevenson 1980;Burk & Haack 1999), and by synthetic aperture radar (Li et al 2004). …”

Section: Introductionmentioning

confidence: 99%

Transcritical rotating flow over topography

Esler¹,

Rump²,

Johnson³

2007

J. Fluid Mech.

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The flow of a one-and-a-half layer fluid over a three-dimensional obstacle of nondimensional height M, relative to the lower layer depth, is investigated in the presence of rotation, the magnitude of which is measured by a non-dimensional parameter B (inverse Burger number). The transcritical regime in which the Froude number F , the ratio of the flow speed to the interfacial gravity wave speed, is close to unity is considered in the shallow-water (small-aspect-ratio) limit. For weakly rotating flow over a small isolated obstacle (M → 0) a similarity theory is developed in which the behaviour is shown to depend on the parameters Γ = (F −1)M −2/3 and ν = B 1/2 M −1/3 . The flow pattern in this regime is determined by a nonlinear equation in which Γ and ν appear explicitly, termed here the 'rotating transcritical small-disturbance equation' (rTSD equation, following the analogy with compressible gasdynamics). The rTSD equation is forced by 'equivalent aerofoil' boundary conditions specific to each obstacle. Several qualitatively new flow behaviours are exhibited, and the parameter reduction afforded by the theory allows a (Γ, ν) regime diagram describing these behaviours to be constructed numerically. One important result is that, in a supercritical oncoming flow in the presence of sufficient rotation (ν & 2), hydraulic jumps can appear downstream of the obstacle even in the absence of an upstream jump. Rotation is found to have the general effect of increasing the amplitude of any existing downstream hydraulic jumps and reducing the lateral extent and amplitude of upstream jumps. Numerical results are compared with results from a shock-capturing shallow-water model, and the (Γ, ν) regime diagram is found to give good qualitative and quantitative predictions of flow patterns at finite obstacle height (at least for M . 0.4). Results are compared and contrasted with those for a two-dimensional obstacle or ridge, for which rotation also causes hydraulic jumps to form downstream of the obstacle and acts to attenuate upstream jumps.

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First common volume ground‐based and space measurements of the mesospheric front in noctilucent clouds

Dalin

Connors

Schofield

et al. 2013

Geophysical Research Letters

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We report on the first common volume ground‐based and space measurements of the mesospheric front in noctilucent clouds (NLCs). The detailed ground‐based observations were performed with automated digital cameras located at the Athabasca University Geophysical Observatory (Canada) on the night of 29–30 June 2012, while simultaneous space measurements were conducted onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite using the Sounding of the Atmosphere using Broadband Emission Radiometry instrument. The large temperature difference of 20–25 K between two different air masses at about 85 km altitude was responsible for the front jump separating the area filled with NLCs from the area with no NLCs. The front jump (soliton) had a pronounced elevation of 12 km up to the altitude of 96 km relative to the undisturbed NLC layer located between 84.5 and 86.3 km. Considering present and previous ground‐based measurements of the NLC height, we conclude that altitude of 96–97 km is the upper limit of possible heights of NLCs.

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Solitary Waves in the Atmosphere

Cited by 54 publications

References 0 publications

An observational study of a shallow gravity current triggered by katabatic flow

An observational study of a shallow gravity current triggered by katabatic flow

Transcritical rotating flow over topography

First common volume ground‐based and space measurements of the mesospheric front in noctilucent clouds

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