Extensive studies of large‐amplitude Kelvin–Helmholtz billows in the lower atmosphere with VHF middle and upper atmosphere radar

Fukao, S.; Luce, Hubert; Mega, Tomoaki; Yamamoto, Masayuki

doi:10.1002/qj.807

Cited by 38 publications

(50 citation statements)

References 102 publications

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“…Among the experimental IGSW studies, radar observations of the waves in the upper troposphere, lower stratosphere, and ionosphere have a major place [14][15][16]. This is related to the widespread networks of continuous atmospheric sensing by pulsed very high frequency (VHF) and high frequency (HF) radars, which often record ISGWs at heights of 2-20 and 50-100 km.…”

Section: Introductionmentioning

confidence: 98%

Internal gravity-shear waves in the atmospheric boundary layer from acoustic remote sensing data

Lyulyukin

Kallistratova

Kouznetsov

et al. 2015

Izv. Atmos. Ocean. Phys.

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The year round continuous remote sounding of the atmospheric boundary layer (ABL) by means of the Doppler acoustic radar (sodar) LATAN 3 has been performed at the Zvenigorod Scientific Station of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, since 2008. A visual analysis of sodar echograms for four years revealed a large number of wavelike patterns in the intensity field of a scat tered sound signal. Similar patterns were occasionally identified before in sodar, radar, and lidar sounding data. These patterns in the form of quasi periodic inclined stripes, or cat's eyes, arise under stable stratifica tion and significant vertical wind shears and result from the loss of the dynamic stability of the flow. In the foreign literature, these patterns, which we call internal gravity shear waves, are often associated with Kelvin-Helmholtz waves. In the present paper, sodar echograms are classified according to the presence or absence of wavelike patterns, and a statistical analysis of the frequency of their occurrence by the year and season was performed. A relationship between the occurrence of the patterns and wind shear and between the wave length and amplitude was investigated. The criteria for the identification of gravity shear waves, mete orological conditions of their excitation, and issues related to their observations were discussed.

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Section: Introductionmentioning

confidence: 98%

Internal gravity-shear waves in the atmospheric boundary layer from acoustic remote sensing data

Lyulyukin

Kallistratova

Kouznetsov

et al. 2015

Izv. Atmos. Ocean. Phys.

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“…KH instability has been widely studied (Thorpe 1973;Koop & Browand 1979;Caulfield et al 1996;Smyth et al 2001) due to the integral role it plays in the transition of a shear flow to turbulence, a classical area of investigation in theoretical fluid mechanics. Applications of KH studies include understanding mixing and transport in (i) the deep ocean (van Haren & Gostiaux 2010) (ii) the oceanic thermocline (Thorpe 2004) (iii) estuarine shear zones (Geyer et al 2010) (iv) density current overflows in the ocean (Legg 2009) and (v) the atmosphere (Luce et al 2010;Fukao et al 2011). Traditionally, the structure and dynamics of KH instability have been studied at relatively low Reynolds number (Re = uδ/ν, where u is one half the velocity difference across the shear layer, δ is the half-width of the shear zone, and ν is the kinematic viscosity of the fluid).…”

Section: Introductionmentioning

confidence: 99%

The characteristics of billows generated by internal solitary waves

et al. 2017

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The spatial and temporal development of shear-induced, overturning billows associated with breaking internal solitary waves is studied by means of a combined laboratory and numerical investigation. The waves are generated in the laboratory by a lock exchange mechanism and they are simulated numerically via a contour-advective, semi-Lagrangian method. The properties of individual billows (maximum height attained, time of collapse, growth rate, speed, wave length, Thorpe scale) are determined in each case and the billow interaction processes are studied and classified. For broad, flat waves, similar characteristics are seen to those in parallel shear flow but, for waves not at the conjugate flow limit, billow characteristics are affected by the spatially-varying, wave-induced shear flow. Wave steepness and wave amplitude are shown to have a crucial influence on determining the type of interaction that occurs between billows and whether billow overturning can be arrested. Examples are given in which billows (i) evolve independently of one another (ii) pair with one another, (iii) engulf/entrain one another and (iv) fail to completely overturn. It is shown that the vertical extent a billow can attain (and the associated Thorpe scales of the billows) are dependent on wave amplitude but that their values saturate once a given amplitude is reached. It is interesting to note that this amplitude is less than the conjugate flow limit amplitude. The number of billows that form on a wave are shown to be dependent on wavelength; shorter waves support fewer but bigger billows than their long wave counterparts for a given stratification.Key words: Authors should not enter keywords on the manuscript, as these must be chosen by the author during the online submission process and will then be added during the typesetting process (see http://journals.cambridge.org/data/relatedlink/jfmkeywords.pdf for the full list)

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“…RIM measurements have revealed a fine structure of KH billows in the jet stream in the mid-latitudes and upper-tropospheric easterly jet in the tropical region (Mega et al, 2010). Fukao et al (2011) carried out a statistical analysis of KH billows in order to quantify their occurrence frequency, spatial scales, energy dissipation rate, and vertical eddy diffusivity.…”

Section: Measurement Resultsmentioning

confidence: 99%

“…Using numerical simulation, Palmer et al (1999) showed that using 3 or more frequencies are required for RIM measurements. For field measurements, four or five frequencies are used typically (e.g., Fukao et al, 2011;Yu & Brown, 2004). The optimal weight vector is given as a solution that minimizes the resulting average power r B .…”

Section: Signal Processingmentioning

confidence: 99%

New Observations by Wind Profiling Radars

Yamamoto¹

2012

Doppler Radar Observations - Weather Radar, Wind Profiler, Ionospheric Radar, and Other Advanced Applications

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Extensive studies of large‐amplitude Kelvin–Helmholtz billows in the lower atmosphere with VHF middle and upper atmosphere radar

Cited by 38 publications

References 102 publications

Internal gravity-shear waves in the atmospheric boundary layer from acoustic remote sensing data

Internal gravity-shear waves in the atmospheric boundary layer from acoustic remote sensing data

The characteristics of billows generated by internal solitary waves

New Observations by Wind Profiling Radars

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