On the spectrum of atmospheric velocity fluctuations seen by MST/ST radar and their interpretation

Gage, K. S.; Nastrom, G. D.

doi:10.1029/rs020i006p01339

Cited by 63 publications

(25 citation statements)

References 25 publications

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“…This scaling, theoretically obtained for all dimensions, has been reported in early experiments of 3D turbulence, such as in a jet of air under laboratory conditions [18], and in effectively-2D turbulence, such as in planetary atmospheres [19], electromagnetic-layer experiments where a thin layer of electrolyte is externally forced by magnetic fields [20], etc. Numerical experiments have also shown such behavior in, e.g.…”

Section: Jhep12(2015)067mentioning

confidence: 90%

Scaling relations in two-dimensional relativistic hydrodynamic turbulence

Westernacher-Schneider

Lehner

2015

J. High Energ. Phys.

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We derive exact scaling relations for two-dimensional relativistic hydrodynamic turbulence in the inertial range of scales. We consider both the energy cascade towards large scales and the enstrophy cascade towards small scales. We illustrate these relations by numerical simulations of turbulent weakly compressible flows. Intriguingly, the fluid-gravity correspondence implies that the gravitational field in black hole/black brane spacetimes with anti-de Sitter asymptotics should exhibit similar scaling relations.

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Section: Jhep12(2015)067mentioning

confidence: 90%

Scaling relations in two-dimensional relativistic hydrodynamic turbulence

Westernacher-Schneider

Lehner

2015

J. High Energ. Phys.

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“…VanZandt (22) showed that the mesoscale spectra of horizontal wind fluctuations as a function of horizontal wavenumber, vertical wavenumber, and frequency are related through the dispersion and polarization relations of inertia-gravity waves. The dominance of inertia-gravity waves at the mesoscale, however, seemed inconsistent with vertical velocity frequency spectra measured from radar in light-wind conditions (25). More recently, Vincent and Eckerman (26) showed that the signature of inertia-gravity waves is recovered after correcting for Dopplershift effects in radar observations.…”

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confidence: 96%

Transition from geostrophic turbulence to inertia–gravity waves in the atmospheric energy spectrum

Callies

Ferrari

Bühler

2014

Proc. Natl. Acad. Sci. U.S.A.

107

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Midlatitude fluctuations of the atmospheric winds on scales of thousands of kilometers, the most energetic of such fluctuations, are strongly constrained by the Earth's rotation and the atmosphere's stratification. As a result of these constraints, the flow is quasi-2D and energy is trapped at large scales-nonlinear turbulent interactions transfer energy to larger scales, but not to smaller scales. Aircraft observations of wind and temperature near the tropopause indicate that fluctuations at horizontal scales smaller than about 500 km are more energetic than expected from these quasi-2D dynamics. We present an analysis of the observations that indicates that these smaller-scale motions are due to approximately linear inertia-gravity waves, contrary to recent claims that these scales are strongly turbulent. Specifically, the aircraft velocity and temperature measurements are separated into two components: one due to the quasi-2D dynamics and one due to linear inertia-gravity waves. Quasi-2D dynamics dominate at scales larger than 500 km; inertia-gravity waves dominate at scales smaller than 500 km. meteorology | atmospheric dynamics | geostrophic turbulence | inertia-gravity waves T he midlatitude high-and low-pressure systems visible in weather maps are associated with winds and temperature fluctuations that we experience as weather. These fluctuations arise from a baroclinic instability of the mean zonal winds at horizontal scales of a few thousand kilometers, commonly referred to as the synoptic scales (1-3). The combined effects of rotation and stratification constrain the synoptic-scale winds to be nearly horizontal and to satisfy geostrophic balance, a balance between the force exerted by the changes in pressure and the Coriolis force resulting from Earth's rotation. It is an open question whether the same constraints dominate in the mesoscale range (i.e., at scales of 10-500 km), or whether qualitatively different dynamics govern flows at these scales.The synoptic-scale flows are turbulent in the sense that nonlinear scale interactions, which lie at the core of the difficulty to predict the weather, exchange energy between different scales of motion (4-7). Under the constraints of rotation and stratification, the synoptic-scale winds are approximately 2D and nondivergent (8, 9). In 2D flows, nonlinear scale interactions tend to transfer energy to larger scales, that is, the synoptic-scale pressure anomalies often merge and form larger ones, contrary to nonlinear scale interactions in 3D flows, which tend to transfer energy to smaller scales (10). Little energy is thus transferred to scales smaller than those at which the synoptic-scale fluctuations are generated through instabilities. Theory and numerical simulations predict that the energy per unit horizontal wavenumber k decays as rapidly as k −3 at wavenumbers larger than the wavenumber corresponding to the instability scale (9, 11). This predicted kinetic energy spectrum is roughly consistent with synoptic-scale observations (9, 12).Long-range passeng...

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“…The frequency spectra of horizontal-wind fluctuations typically show an f −5/3 dependence, where f is the frequency (e.g. Gage and Nastrom, 1985). Therefore a greater degree of natural variability is expected between the 30 min averaged radar-derived horizontal wind components than between the single cycle components.…”

Section: Radarmentioning

confidence: 99%

Validation of a new signal processing scheme for the MST radar at Aberystwyth

et al. 2008

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Abstract. This paper describes a new signal processing scheme for the 46.5 MHz Doppler Beam Swinging windprofiling radar at Aberystwyth, in the UK. Although the techniques used are similar to those already described in literature -i.e. the identification of multiple signal components within each spectrum and the use of radial-and time-continuity algorithms for quality-control purposes -it is shown that they must be adapted for the specific meteorological environment above Aberystwyth. In particular they need to take into account the three primary causes of unwanted signals: ground clutter, interference, and Rayleigh scatter from hydrometeors under stratiform precipitation conditions. Attention is also paid to the fact that short-period gravitywave activity can lead to an invalidation of the fundamental assumption of the wind field remaining stationary over the temporal and spatial scales encompassed by a cycle of observation. Methods of identifying and accounting for such conditions are described. The random measurement error associated with horizontal wind components is estimated to be 3.0-4.0 m s −1 for single cycle data. This reduces to 2.0-3.0 m s −1 for data averaged over 30 min. The random measurement error associated with vertical wind components is estimated to be 0.2-0.3 m s −1 . This cannot be reduced by time-averaging as significant natural variability is expected over intervals of just a few minutes under conditions of short-period gravitywave activity.

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On the spectrum of atmospheric velocity fluctuations seen by MST/ST radar and their interpretation

Cited by 63 publications

References 25 publications

Scaling relations in two-dimensional relativistic hydrodynamic turbulence

Scaling relations in two-dimensional relativistic hydrodynamic turbulence

Transition from geostrophic turbulence to inertia–gravity waves in the atmospheric energy spectrum

Validation of a new signal processing scheme for the MST radar at Aberystwyth

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