Simultaneous Radar, Aircraft and Meteorological Investigations of Clear Air Turbulence

Glover, Kenneth M.; Boucher, Roland J.; Óttersten, Hans; Hardy, Kenneth R.

doi:10.1175/1520-0450(1969)008<0634:sraami>2.0.co;2

Cited by 19 publications

(6 citation statements)

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“…Strong wind shears may not be a necessary requirement for clear-air layers in the stable regime, but abundant evidence is now available that these stratified echoes, particularly at higher altitudes, generally are associated with pronounced vertical wind shears [Lane, 1968;Hardy and Ottersten, 1968b;Glover et al, 1969]. Marked turbulence is also generally present in the vicinity of these layers, as evidenced by an increasing number of joint radar and aircraft studies of CAT [Hicks et al, 1967;Buehler, 1967;Hardy ahd Ottersten, 1968b;Glover et al, 1968Glover et al, , 1969Crane, 1968a;Buehler et al, 1968Buehler et al, , 1969Hardy et al, 1969). These studies were preceded by the radar detection of the tropopause [Atlas et al, 1966b, c] and the prediction that these echoes were associated with significant CAT.…”

Section: The Same Type C4 Convective Cells Is Reported Bymentioning

confidence: 99%

Atmospheric Structure and Radar Backscattering in Clear Air

Óttersten¹

1969

Radio Science

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177

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This study summarizes advances in radar backscattering from refractive index irregularities in the clear air and its relationship to atmospheric structure and turbulence. This recent discipline of radar meteorology originated from radar angel studies and the efforts to explain these mysterious echoes. The significance of specular atmospheric radar reflections now appears limited, and consequently this study is devoted entirely to radar backscattering from turbulent fluctuations in the clear‐air refractive index. Two regimes of atmospheric turbulence are distinguished: (1) in the convective domain, backscattering from water vapor fluctuations outlines regular, three‐dimensional clear‐air structures associated with buoyant, moist air parcels; (2) in the stable regime, horizontally stratified clear‐air echoes originate from water vapor and/or temperature perturbations due to wind‐shear‐generated turbulent mixing in zones of enhanced static stability. Theoretical relationships are given between the radar reflectivity and the refractive index microstructure for the general case, for the isotropic case, and for the inertial subrange. The connection between the microstructure and the atmospheric mean fields is illustrated for a simplified situation in the stable regime; this relationship provides insight to the radar backscattering from clear‐air turbulence (CAT). It is concluded that strong CAT will be associated with zones of increased refractive index variability and enhanced radar returns. A brief résumé of experimental work illustrates the application of radar methods in clear‐air research and summarizes characteristic features of clear‐air structures.

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Section: The Same Type C4 Convective Cells Is Reported Bymentioning

confidence: 99%

Atmospheric Structure and Radar Backscattering in Clear Air

Óttersten¹

1969

Radio Science

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177

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“…Atlas et a1 (196613) and Hardy et al (1966) have shown that the intensity of the turbulence can be expressed by a parameter Cn2 which should be directly proportional to the reflectivity of the clear air echoes. Measurements of radar reflectivity made in conjunction with a large number of aircraft measurements support the validity of this approach by demonstrating that CAT always existed in the vicinity of clear air echoes and that, although not all CAT gave a detectable echo, intense CAT was consistently more likely to be detected than weak CAT (Glover et al 1969, Glover andDuquette 1970). One of the problems of using radar reflectivity as a measure of CAT intensity, however, is the difficulty in objectively distinguishing clear air echoes from precipitation echoes without resorting to multi-wavelength measurements.…”

Section: Detection Of Clear Air Turbulencementioning

confidence: 87%

Meteorological applications of radar

Browning

1978

Rep. Prog. Phys.

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Radar has been used by meteorologists for 30 years or so but it is only during the latter half of this period that the full measure of its versatility has come to be recognised. Operationally important techniques have been or are being developed to identify and track severe storms, to provide warning of tornadoes, to measure and forecast rainfall quantitatively, and to measure winds, turbulence and wind shear. At the same time research meteorologists are using specialised radar techniques to investigate many poorly understood aspects of atmospheric behaviour : to identify the physics of clear air turbulence, the dynamics of fronts, the structure of the atmospheric boundary layer, the three-dimensional airflow and trajectories of hailstones in thunderstorms, and the patterns of precipitation within mid-latitude depressions. Studies such as these are giving fresh impetus to a branch of meteorology, mesoscale meteorology, which largely because of the difficulty of obtaining definitive observations has hitherto been a neglected field. This review highlights the strengths and limitations of radar as a tool for observing the atmosphere and attempts to provide a balanced view of its many applications in meteorology.

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“…Various investigators have described joint radar and aircraft studies of CAT (Hicks et al, 1967;Glover et al, 1969;Crane, 1970;Glover and Duquette, 1970). Using the radars at Wallops Island, Glover and Duquette (1970) found that all altitude intervals corresponding to clear air radar layers between 0.5 and 15 km, when probed with fighter jet-aircraft, were turbulent. The results of the 53 flights during the winters of 1969 and 1970 are given in (T14.3).…”

Section: Waves and Turbulence In A Stratified Atmospherementioning

confidence: 99%

Remote sensing of the troposphere

Zissis¹

1974

Remote Sensing of Environment

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Simultaneous Radar, Aircraft and Meteorological Investigations of Clear Air Turbulence

Cited by 19 publications

References 0 publications

Atmospheric Structure and Radar Backscattering in Clear Air

Atmospheric Structure and Radar Backscattering in Clear Air

Meteorological applications of radar

Remote sensing of the troposphere

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