A Theoretical Study of Sporadic-E Structure in the Light of Radio Measurements

Tao, Kazuhiko

doi:10.1016/b978-0-08-009744-2.50024-2

Cited by 8 publications

(7 citation statements)

References 10 publications

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“…Tao et al [1960] started investigations of 50-Mttz forward-scatter signals at various distances. Tao [1961Tao [ , 1962a and Tao and Wait [1962] deduced that, when foE8 = 12 Mttz, reflection was specular from a layer 300 meters to I km thick, and when foE8 = 6 Mttz, scattering occurred from blobs having a scale size 175 meters horizontal and 50 meters vertical. It is far from obvious where these values came from, or the error in the estimate.…”

Section: Harwood [1961] and Egan And Petersen [1962] Pointed Ou• Tha•mentioning

confidence: 99%

Production and prediction of sporadic E

Whitehead¹

1970

Reviews of Geophysics

227

118

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This is a survey of the experimental observations and theories of formation of all types of sporadic E. The wind‐shear theory is most likely to explain temperate‐zone sporadic E. In the equatorial zone, VHF reflections are most probably due to the two‐stream plasma instability, though gradient instabilities may play a part in producing the irregularities that cause HF vertical‐incidence reflection. In the auroral zone, energetic particles dumped by any one of a variety of mechanisms cause ionization. This ionization has to be moved into thin layers of irregularities to cause auroral sporadic E and radio aurora reflections. Many recommendations are made to further the understanding of and the prediction of sporadic E for communication purposes.

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Section: Harwood [1961] and Egan And Petersen [1962] Pointed Ou• Tha•mentioning

confidence: 99%

Production and prediction of sporadic E

Whitehead¹

1970

Reviews of Geophysics

227

118

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“…It is well known that reflections from mid-Curves in Figure 6 latitude sporadic E are n. ot always specular. Very sophisticated theoretical approaches to the scattering problem are now available [see Bowles, 1964;Tao, 1962;Tatarski, 1961;Chernov, 1960]. An application of these theories to the problem of scattering from midiarttude E• is beyond the scope of this paper.…”

Section: Table 1 Blanketing and 'Cutoff' Frequencies Scattering Frommentioning

confidence: 99%

Physical significance of theE_sparameters ƒ_bE_s, ƒE_s, and ƒ_oE_s: 2. Causes of partial reflections fromE_s

Reddy¹

1968

J. Geophys. Res.

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Adoption of the light-limitation method for preventing reservoir eutrophication requires an efficient destratification system. Here, bubble plume system was discussed. The stratification is destroyed with the evolution of the intermediate layer, which is bounded from the upper and the lower layers by fronts. Most efficient destratification is achieved with the equivalent plume number of 1300. The upper front density gap is parameterized with the bubbling rate, the depth and intensity of the initial ther-mocline. For the light limitation method, the bubbling rate should be large enough to make it small. For the hypolimnetic aeration, on the other hand, the bubbling is to be weak as to keep it large.

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“…I)ecameter wave!ength radar backscatter from sporadic E indicates that field-aligned irregularities are common [Goodwin, 1965], and a theory of sporadic E scattering by turbulent irregularities, developed by Booker [1956Booker [ , 1959 before the advent Of the wind-shear theory, is consistent with these data if the scattering irregularities are considered to have a characteristic scale of 80 to 570 meters. A similar theory was developed by Tao [1962], in which the turbulence m;•ght be a result of high shearing winds; it was found that irregularities of 50 meters vertical scale should be common. Thus far, then, the rocket and radio wave measurements of charge density fine structure are consistent with a theory of scattering from turbulent irregularities.…”

Section: Rao and Russell [1971] Perform A Linear Instability Analysismentioning

confidence: 69%

Decameter and meter wavelength radar studies of artificial plasma clouds in the lower ionosphere, 2. Unstable evolution in the lowerElayer and some implications, regarding sporadicE

Davis¹

1971

J. Geophys. Res.

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Radio frequency scattering experiments have indicated that irregular fluid motions of tens of meters spatial scale and tenths of seconds temporal scale occur in the E region. It has been suggested that there can also occur in this region a dissipative plasma instability (similar to what has been termed the gradient‐drift or E×B instability in previous work) that displays these spatial and temporal scales and that may be of importance in the evolution of sporadic E. This paper describes an attempt to study the circumstances under which such an instability might appear by injecting alkali plasma clouds into the lower E region and observing them with decameter and meter wavelength, coherent‐pulse‐Doppler radar. After an initial blast‐wave‐driven expansion phase, an alkali plasma cloud undergoes a period of irregular behavior, in which a number of discrete echoes from seemingly coherent, large, short‐lived reflectors appear superimposed on the generally diffuse plasma cloud radar echo. Their large apparent size and spectral discreteness indicate that they may arise from an ordered, possibly wavelike structure, which must involve the entire plasma cloud. Comparison of the observed growth rates and probable spatial scales of the instabilities in the alkali plasma clouds with order‐of‐magnitude calculations of these quantities based on linear instability analysis confirms that the postulated plasma instability can indeed explain the observed behavior. In one phase of plasma cloud evolution a reflecting layer similar to sporadic E is formed, which permits decameter wavelength radiation, incident obliquely on the cloud, to be reflected back to earth in much the same manner as sky‐wave transmission is achieved via sporadic E. The similarity in behavior of an artificial sporadic E patch to the natural variety is evident. Also, a nonlinear, two‐dimensional plasma instability analysis is capable of explaining the spectral appearance and temporal variation of the decameter radar data from the alkali plasma cloud. An association is suggested between these results and the mechanism by which temperate latitude sporadic E is formed.

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A Theoretical Study of Sporadic-E Structure in the Light of Radio Measurements

Cited by 8 publications

References 10 publications

Production and prediction of sporadic E

Production and prediction of sporadic E

Physical significance of theE_sparameters ƒ_bE_s, ƒE_s, and ƒ_oE_s: 2. Causes of partial reflections fromE_s

Decameter and meter wavelength radar studies of artificial plasma clouds in the lower ionosphere, 2. Unstable evolution in the lowerElayer and some implications, regarding sporadicE

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A Theoretical Study of Sporadic-E Structure in the Light of Radio Measurements

Cited by 8 publications

References 10 publications

Production and prediction of sporadic E

Production and prediction of sporadic E

Physical significance of theEsparameters ƒbEs, ƒEs, and ƒoEs: 2. Causes of partial reflections fromEs

Decameter and meter wavelength radar studies of artificial plasma clouds in the lower ionosphere, 2. Unstable evolution in the lowerElayer and some implications, regarding sporadicE

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Product

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Physical significance of theE_sparameters ƒ_bE_s, ƒE_s, and ƒ_oE_s: 2. Causes of partial reflections fromE_s