Linear theory and modeling of the Rayleigh‐Taylor instability leading to the occurrence of equatorial spread <i>F</i>

Sultan, P. J.

doi:10.1029/96ja00682

Cited by 505 publications

(586 citation statements)

References 45 publications

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“…The plasma bubbles with shorter lifetimes in the present study were observed in October 2011 when solar activity approached maximum. Sultan [1996] derived the flux tube integrated growth rate of the generalized Rayleigh-Taylor instability:…”

Section: Discussionmentioning

confidence: 99%

Generation and characteristics of equatorial plasma bubbles detected by the C/NOFS satellite near the sunset terminator

et al. 2012

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We present the observations of equatorial plasma bubbles in the evening sector by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite during 2011. We illustrate with a few examples the overall properties of the equatorial ionosphere as the solar activity approached maximum. C/NOFS was often below the F peak and this allowed us to examine the early phases of irregularity formation. We show examples when C/NOFS detected a continuous generation of plasma bubbles near the sunset terminator over eight successive orbits (∼12 h). A clear prereversal enhancement of upward plasma drift occurred between 18:00 and 19:00 LT when plasma bubbles were detected by C/NOFS, and the peak value of the upward ion drift at or near the magnetic equator was 40–70 m s−1. In some cases, C/NOFS was well below the Fpeak and detected wide regions with very low plasma density over ∼3000 km in longitude in the evening sector, and plasma bubbles were generated within the low‐density region. C/NOFS also detected simultaneous existence of plasma bubbles between 19:00 and 03:00 LT, corresponding to a longitudinal coverage of ∼12,000 km. Significant differences in the characteristics of plasma bubbles between periods of low and high solar activity are identified. Large plasma bubbles occur in the midnight‐dawn sector at low solar activity but in the evening sector at high solar activity. The lifetime of plasma bubbles is long (7 h or longer) at low solar activity but is short (∼3 h) at high solar activity. Broad plasma depletions occur near dawn at low solar activity, but wide low‐density regions with multiple plasma bubbles occur in the evening sector at high solar activity.

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Section: Discussionmentioning

confidence: 99%

Generation and characteristics of equatorial plasma bubbles detected by the C/NOFS satellite near the sunset terminator

et al. 2012

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“…The results for magnetically disturbed periods are discussed below. The role of the vertical plasma drifts on the generation and evolution of these irregularities can be determined from their effects on the time integrated growth rate of the RayleighTaylor instability [e.g., Maruyanta, 1988; Sultan, 1996]. We can estimate these effects by examining the evening and nighttime Jicamarca average quiet time vertical drifts presented in Figure 7.…”

Section: Spread F During Premidnight Hoursmentioning

confidence: 99%

Effects of the vertical plasma drift velocity on the generation and evolution of equatorial spread F

Fejer¹,

Scherliess²,

Paula³

1999

J. Geophys. Res.

644

754

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Abstract. We use radar observations from the Jicamarca Observatory from 1968 to 1992 to study the effects of the F region vertical plasma drift velocity on the generation and evolution of equatorial spread F. The dependence of these irregularities on season, solar cycle, and magnetic activity can be explained as resulting from the corresponding effects on the evening and nighttime vertical drifts. In the early night sector, the bottomside of the F layer is almost always unstable. The evolution of the unstable layer is controlled by the history of the vertical drift velocity. When the drift velocities are large enough, the necessary seeding mechanisms for the generation of strong spread F always appear to be present. The threshold drift velocity for the generation of strong early night irregularities increases linearly with solar flux. The geomagnetic control on the generation of spread F is season, solar cycle, and longitude dependent. These effects can be explained by the response of the equatorial vertical drift velocities to magnetospheric and ionospheric disturbance dynamo electric fields. The occurrence of early night spread F decreases significantly during equinox solar maximum magnetically disturbed conditions due to disturbance dynamo electric fields which decrease the upward drift velocities near sunset. The generation of late night spread F requires the reversal of the vertical velocity from downward to upward for periods longer than about half an hour. These irregularities occur most often at -0400 local time when the prompt penetration and disturbance dynamo vertical drifts have largest amplitudes. The occurrence of late night spread F is highest near solar minimum and decreases with increasing solar activity probably due to the large increase of the nighttime downward drifts with increasing solar flux.

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“…[21] Following Sultan [1996], a simplified expression for the Rayleigh-Taylor instability growth rate can be written as…”

Section: Modeling Investigation Of the Rayleigh-taylor Instability Grmentioning

confidence: 99%

“…Also, the nonzero field line integrated Pedersen conductivity of the E region was regarded as capable of affecting the growth rate. Subsequent modeling investigations evaluated the role of transequatorial neutral winds, zonal electric fields, density gradients, presence of an E region and chemical recombination on the flux tube integrated RT instability growth rate [Sultan, 1996].…”

Section: Introductionmentioning

confidence: 99%

On the nature of low‐latitude E_s influencing the genesis of equatorial plasma bubble

et al. 2013

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[1] The potential influence of the postsunset low-latitude sporadic E (E s ) on the genesis of equatorial plasma bubble (EPB) has been investigated using observations made with the Gadanki radar and two ionosondes, one located at the magnetic equator providing the F layer characteristics and another at magnetically low-latitude providing the E s parameters. Observations revealed that the occurrence of EPB was associated with either the disruption of E s or presence of nonblanketing-type E s or intermittently occurring blanketing E s at low-latitude. In contrast, when blanketing E s occurred for a relatively long duration in the sunset hours, EPB did not occur. Model computation clearly reveals that the growth of the Rayleigh-Taylor instability depends very much on the thickness, height, and shape of electron density profile of the E s layer. The above findings thus suggest that low-latitude E s variability plays decisive role on the day-to-day variability of EPB through the growth rate of the Rayleigh-Taylor instability.

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Linear theory and modeling of the Rayleigh‐Taylor instability leading to the occurrence of equatorial spread F

Cited by 505 publications

References 45 publications

Generation and characteristics of equatorial plasma bubbles detected by the C/NOFS satellite near the sunset terminator

Generation and characteristics of equatorial plasma bubbles detected by the C/NOFS satellite near the sunset terminator

Effects of the vertical plasma drift velocity on the generation and evolution of equatorial spread F

On the nature of low‐latitude E_s influencing the genesis of equatorial plasma bubble

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Linear theory and modeling of the Rayleigh‐Taylor instability leading to the occurrence of equatorial spread F

Cited by 505 publications

References 45 publications

Generation and characteristics of equatorial plasma bubbles detected by the C/NOFS satellite near the sunset terminator

Generation and characteristics of equatorial plasma bubbles detected by the C/NOFS satellite near the sunset terminator

Effects of the vertical plasma drift velocity on the generation and evolution of equatorial spread F

On the nature of low‐latitude Es influencing the genesis of equatorial plasma bubble

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On the nature of low‐latitude E_s influencing the genesis of equatorial plasma bubble