E region coupling effects on the Perkins spread F instability

Klevans, E.H.; Imel, G.

doi:10.1029/ja083ia01p00199

Cited by 20 publications

(13 citation statements)

References 5 publications

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“…Observations also indicate that the averaged value for Σ P 0 E can vary between 0.03 and 0.2 mho, regardless of solar activity [ Harper and Walker , 1977; Klevans and Imel , 1978; Burnside et al , 1983b], while the averaged value for Σ P 0 F can vary between 0.02 and 0.9 mho during solar minimum and between 0.4 and 1.9 mhos during solar maximum. Thus a thick E s layer with Σ H Es ≈ 1 mho should activate the E s L instability under solar minimum conditions but not so easily under solar maximum conditions.…”

Section: Simplified Es Layer Instabilitymentioning

confidence: 99%

On the coupling of layer instabilities in the nighttime midlatitude ionosphere

Tsunoda

2006

J. Geophys. Res.

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[1] There are two plasma-structuring mechanisms that are known to operate at night in the midlatitude ionosphere, the Perkins instability (Perkins, 1973) in the F region, and the more recently discovered sporadic-E layer (E s L) instability (Cosgrove and Tsunoda, 2002) in the E region. Both are layer processes, whose coupled response has been shown to be more unstable than either by itself . Derived growth rates, however, were given only in terms of the most unstable mode; exactly how the individual growth rates in the E s and F layers are affected by coupling remains to be shown. To do so, simplified descriptions of the instabilities are derived in this paper to show that the growth rates of both layer instabilities are enhanced by additional vertical drifts produced by polarization electric fields that map between regions along geomagnetic field lines. Key findings are (1) largest enhancement is in the growth rate of F region structure (g P c ), (2) g P c is controlled by the E s L instability, and (3) additional positive feedback to the E s L instability occurs because of its dependence on the field-line-integrated Pedersen conductivity of the F layer. An important byproduct of this study is the finding that a more consistent interpretation of existing data is possible, if we assume that the coupled system involves a large-scale, but finite-sized, E s patch. These new findings seem to explain several puzzling observations that are associated with midlatitude spread F.

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Section: Simplified Es Layer Instabilitymentioning

confidence: 99%

On the coupling of layer instabilities in the nighttime midlatitude ionosphere

Tsunoda

2006

J. Geophys. Res.

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“…Define the Pedersen conductivity, Hall conductivity, current perpendicular to the magnetic field line and total electron density in one layer as [8] ,…”

Section: Deductionsmentioning

confidence: 99%

“…where ϕ E /ϕ F is the transfer efficiency of the magnetic field line and can be get from the Ohm law of the resistive layer [8,10] . It is a quantity greater than zero.…”

Section: The Coupling Of the Constant E Region Conductivity To F Regionmentioning

confidence: 99%

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Effect of the Coupling of Different Ionospheric Regions on the Nighttime F Region Irregularities in Mid‐Latitude

Zhang¹,

Xiao²

2000

Chinese J of Geophysics

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The formation and evolution of ionospheric irregularities are closely connected with the instabilities of ionospheric plasma. However, no much consideration of the coupling between upper and lower parts of the ionosphere has ever been taken so far in the study of such instabilities in mid‐ and low‐latitudes. In this paper, a full discussion was presented on the roles played by the existence of both E region Pedersen and Hall conductivity and F region Pedersen conductivity. A complete, common expression of ionospheric plasma gradient‐drift instability under such a coupling was deduced for mid‐ and low‐latitudes based on a three‐layer model developed earlier only for high latitude area. With this model, the observed phenomenon that in some places, the instability occurrence rate is higher in top F region than in the bottom‐side can be explained well. Besides, the model also shows that the evolution of nighttime F region gradient‐drift instability will be slowed down due to the coupling between E and F regions and make the instability growth rate vary with directions in mid‐latitude. It is concluded that the development of gradient‐drift instability in nighttime F region not only depends on the local conditions, but also affected by state of E region that is connected to F region with the same geomagnetic field lines.

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“…The only F-region sources that have been identified, however, are the Perkins and gradient-drift instabilities [Perkins, 1973]. Their growth rates (y) are discouragingly small and susceptible to further reduction (e.g., factor of three) if an underlying E layer is present [Klevans and Imel, 1978]. Both instabilities have a ythat depends on a variation in the field-line-integrated Pedersen conductivity (or conduc-F tance) of the F layer, Zp, which must be produced by a change in the ion-neutral collision frequency (Vin Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Coupled electrodynamics in the nighttime midlatitude ionosphere

Tsunoda¹,

Cosgrove²

2001

Geophysical Research Letters

125

133

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Abstract. We describe a new, self-consistent scenario in which sporadic-E doublets, height bands of upward-displaced F-layer profiles, F-region plasma depletions, and radar backscatter plumes, are all manifestations of a coupled electrodynamical response by the nighttime midlatitude ionosphere to the presence of a traveling ionospheric disturbance (TID). We show that the response consists of (1) formation of image plasma structure in the E region, (2) initiation of a Hall-current-driven polarization process by the E-region plasma structure, and (3) mapping of the polarization electric field to the F region, where it strengthens the electrical properties of the TID that initiated the E-region processes. This scenario provides ready answers for several, hitherto puzzling, questions and a basis for new directions on this research topic.

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E region coupling effects on the Perkins spread F instability

Cited by 20 publications

References 5 publications

On the coupling of layer instabilities in the nighttime midlatitude ionosphere

On the coupling of layer instabilities in the nighttime midlatitude ionosphere

Effect of the Coupling of Different Ionospheric Regions on the Nighttime F Region Irregularities in Mid‐Latitude

Coupled electrodynamics in the nighttime midlatitude ionosphere

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