Occurrence of equatorial F region irregularities: Evidence for tropospheric seeding

McClure, J. P.; Singh, Sardul; Bamgboye, D. K.; Johnson, Francis S.; Kil, H.

doi:10.1029/98ja02749

Cited by 181 publications

(253 citation statements)

References 39 publications

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“…Providing a full explanation of these deviations from model predictions greatly exceeds the scope of this observational report. However, the role of interhemispheric winds in suppressing EPB activity has been discussed in the literature (Mendillo et al, 1992;Kil and Heelis, 1998) and can easily be compared with data shown in Fig. 3.…”

Section: Discussionmentioning

confidence: 99%

“…The Tsunoda model addresses effects of systematic variations in Pedersen conductance and Sq-generated electric fields in the dusk sector. Random events, such as sporadic E layers (Whitehead, 1970;Stephan et al, 2002) and gravity waves (McClure et al, 1998;Singh et al, 1997), act to suppress and stimulate EPB formation, respectively. The magnetic storm of 6 November 2001 illustrates two related random aspects of EPB formation.…”

Section: Discussionmentioning

confidence: 99%

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Seasonal-longitudinal variability of equatorial plasma bubbles

et al. 2004

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Abstract. We compare seasonal and longitudinal distributions of more than 8300 equatorial plasma bubbles (EPBs) observed during a full solar cycle from 1989-2000 with predictions of two simple models. Both models are based on considerations of parameters that influence the linear growth rate, γ RT , of the generalized Rayleigh-Taylor instability in the context of finite windows of opportunity available during the prereversal enhancement near sunset. These parameters are the strength of the equatorial magnetic field, B eq , and the angle, α, it makes with the dusk terminator line. The independence of α and B eq from the solar cycle phase justifies our comparisons.We have sorted data acquired during more than 75 000 equatorial evening-sector passes of polar-orbiting Defense Meteorological Satellite Program (DMSP) satellites into 24 longitude and 12 one-month bins, each containing ∼250 samples. We show that: (1) in 44 out of 48 month-longitude bins EPB rates are largest within 30 days of when α=0 • ; (2) unpredicted phase shifts and asymmetries appear in occurrence rates at the two times per year when α≈0 • ; (3) While EPB occurrence rates vary inversely with B eq , the relationships are very different in regions where B eq is increasing and decreasing with longitude. Results (2) and (3) indicate that systematic forces not considered by the two models can become important. Damping by interhemispheric winds appears to be responsible for phase shifts in maximum rates of EPB occurrence from days when α=0 • . Low EPB occurrence rates found at eastern Pacific longitudes suggest that radiation belt electrons in the drift loss cone reduce γ RT by enhancing E-layer Pedersen conductances. Finally, we analyze an EPB event observed during a magnetic storm at a time and place where α≈ −27 • , to illustrate how electric-field penetration from high latitudes can overwhelm the damping effects of weak gradients in Pedersen conductance near dusk.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Seasonal-longitudinal variability of equatorial plasma bubbles

et al. 2004

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“…Kil and Heelis, 1998). McClure et al (1998) proposed the importance of gravity waves to initiate the R-T instability process.…”

Section: Fe Pmentioning

confidence: 99%

Relation between the occurrence rate of ESF and the equatorial vertical plasma drift velocity at sunset derived from global observations

2008

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Abstract. In this study, we investigate two global climatological data sets; the occurrence rate of Equatorial Spread-F (ESF), associated with equatorial plasma irregularities, at ∼400 km altitude obtained from CHAMP observations, and the evening equatorial vertical plasma drift, v z , from ROCSAT-1 measurements. First, as retrieved for a solar flux level of F10.7=150, the longitudinal variation of the two independently derived quantities correlates between 84% and 93% in the seasons December solstice, equinox and June solstice. The highest correlation is found for the solstice seasons when v z is integrated over local time around the prereversal enhancement (PRE) and displaced 6 • towards east. The integrated v z is a suitable estimate of the ionospheric height at the time just after the PRE and the 6 • displacement is consistent with ESF eastward drift during 2 h which is assumed between creation and detection at satellite altitudes. Second, our analyses reveal a global threshold v z which is required to observe ESF at satellite altitudes. This threshold depends linearly on solar flux with correlations of 97%. Both results bring global evidence on the linear relations between ESF and the vertical plasma drift which have been proven only by local observations so far. This paper includes the first global map of the seasonal/longitudinal variation of the ESF occurrence rate over local time being valid for high solar flux years [2001][2002][2003][2004]. The map reveals, e.g. a longitudinal dependence of the persistence of the plasma irregularities indicating that longitude dependent mechanisms other than the PRE determine the ESF lifetime.

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“…Several investigators (e.g. Rottger, 1977Rottger, , 1981McClure et al, 1998) have studied the initiation of ESF related to the tropospheric disturbance sources. Also, several investigators (e.g.…”

Section: Observations Of Plasma Bubbles During Low Spread-f Seasonmentioning

confidence: 99%

Generation of large-scale equatorial F-region plasma depletions during lowrange spread-F season

Sahai

Fagundes²,

Abalde³

et al. 2004

Ann. Geophys.

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Occurrence of equatorial F region irregularities: Evidence for tropospheric seeding

Cited by 181 publications

References 39 publications

Seasonal-longitudinal variability of equatorial plasma bubbles

Seasonal-longitudinal variability of equatorial plasma bubbles

Relation between the occurrence rate of ESF and the equatorial vertical plasma drift velocity at sunset derived from global observations

Generation of large-scale equatorial F-region plasma depletions during lowrange spread-F season

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