Microstructure of Radar Echo Layers in the Clear Atmosphere

Metcalf, James I.

doi:10.1175/1520-0469(1975)032<0362:moreli>2.0.co;2

Cited by 13 publications

(14 citation statements)

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“…Internal gravity waves in the stable PBL Metcalf (1974) showed the time-bight chart of echo layers and the mean wind velocities, mean potential temperature and refractive index in the stable PBL. One can see the wavy thin layers which gradually grow with time.…”

Section: Introductionsupporting

confidence: 86%

“…Strong shear and stable stratification sustain the existence of the critical level. These wavy thin layers usually contain many mini-K-H billows as reported by Metcalf (1974) and do not expand over a certain limited vertical dimension. Such wavy thin layers are very frequently generating in the stable PBL and could be related to some mechanisms which we want to make clear in this paper.…”

Section: Introductionmentioning

confidence: 77%

“…The unstable regions which are formed in the vicinity of the critical level derived by the present numerical simulations have quite similar features as the observation shown by Metcalf (1974). We never want to conclude that all unstable regions are caused by existence of the critical level.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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Turbulent Layers Associated with a Critical Level in the Planetary Boundary Layer

Tanaka

1975

Journal of the Meteorological Society of Japan

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Formation of thin turbulent layers in a stably stratified fluid is discussed in combination with a critical level and internal gravity waves.A series of numerical simulations by using nonlinear model of an incompressible fluid reveal that very thin unstable layers (local Richardson number <0.25) are formed in the vicinity of the critical level. Mini-K-H billows can be expected to grow up and break into turbulence in the thin unstable layers. Long-time numerical calculations show that such thin unstable layers which contain the mini-K-H billows and turbulence roll up at their edges and form Cat's eye patterns associated with large amplitude K-H billows deformed by the critical level. This result also seems to open a new perspective to the critical level theory itself.Some observations in the planetary boundary layer provide good evidences to the results of the present numerical simulations.

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Section: Introductionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 77%

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Turbulent Layers Associated with a Critical Level in the Planetary Boundary Layer

Tanaka

1975

Journal of the Meteorological Society of Japan

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“…Effects of tilted specular scatterers are considered also by Metcalf and Atlas (1973) and Metcalf (1975), for FM-CW radar. A few studies report aspect sensitivity for wavelengths much smaller than that of VHF radar (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…A few studies report aspect sensitivity for wavelengths much smaller than that of VHF radar (e.g. Metcalf, 1975;Kallistratova and Petenko, 1993), implying that atmospheric microstructure may be slightly anisotropic on scales as small as centimetres.…”

Section: Introductionmentioning

confidence: 99%

Asymmetry of atmospheric microstructure over synoptic scales

Worthington

2001

Ann. Geophys.

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Abstract. Distortions are often seen in the angular distribution of echo-power from VHF wind-profiling radars, suggesting that thin stable layers, within the air flow, are distorted and tilted from horizontal. In vertical shear of the horizontal wind, the distribution of the layer tilt angles becomes skewed. A case study using six days of VHF radar data and synoptic charts above western Europe indicates that this asymmetry of atmospheric microstructure can exist throughout the troposphere and lower stratosphere, above and below the jet wind maximum, over horizontal scales of thousands of kilometres.

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MST radar observations of turbulent altocumulus layers

Worthington¹

2015

Atmospheric Science Letters

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Radar studies of turbulent layers have focused on Kelvin-Helmholtz instabilities caused by vertical shear of horizontal wind, also breaking gravity waves. This study examines another type of turbulent layer, common but rarely studied. Aberystwyth Meso-Strato-Troposphere (MST) radar shows layers of turbulence where there is no unusual wind shear or breaking gravity waves. In three case studies, these layers have a common characteristic of saturated air, reducing the stability to cause possible convective or shear instability. The associated cloud may be already well-known altocumulus. Another case study using the MU radar shows how three-dimensional convective structure can be revealed using a 64-beam method.

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Microstructure of Radar Echo Layers in the Clear Atmosphere

Cited by 13 publications

References 0 publications

Turbulent Layers Associated with a Critical Level in the Planetary Boundary Layer

Turbulent Layers Associated with a Critical Level in the Planetary Boundary Layer

Asymmetry of atmospheric microstructure over synoptic scales

MST radar observations of turbulent altocumulus layers

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