Solar flux effects on the equatorial evening vertical drift and meridional winds over Brazil: A comparison between observational data and the IRI model and the HWM representations

Abdu, M. A.; Batista, I. S.; Brum, C. G.; MacDougall, J. W.; Santos, A. M.; Souza, J. R.; Sobral, J. H. A.

doi:10.1016/j.asr.2010.06.009

Cited by 27 publications

(37 citation statements)

References 38 publications

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“…These conditions are satisfied in the quiet-time ionosphere during very high solar flux. For example, during summer and very high solar flux period in the Brazilian longitude sector, the PRVD over equator often meets these conditions [Abdu et al, 2010]. Very large PRVD, up to about v p =80 m/s, are often observed over Jicamarca during very high solar flux equinoctial season [Fejer et al, 1989].…”

Section: Discussionmentioning

confidence: 99%

“…For example, using incoherent scatter radar, Fejer et al [1991] have observed very large PRVDs, up to about 80 m/s, during equinoctial periods when the solar flux was very high (F10.7 > 200). During very high solar flux summer season over São Luís, the PRVD turns out to present a quasi-Gaussian variation with the peak value of v p >60 m/s and minimum value v m >20 m/s [Abdu et al, 2010] that satisfy the threshold conditions. It may be thus said that the longitudinally varying PRVD is capable of seeding the CII and give rise to the EPB during very high solar flux summer (over São Luís) and equinoctial (over Jicamarca) season.…”

Section: Simulation With Realistic Ionospheric Dynamics Obtained mentioning

confidence: 99%

“…It is evident from this figure that within the zonal region covering the sunset terminator, the PRVD varies from the minimum value (v m ) of 20 m/s to the peak value (v p ) of 50-55 m/s within 1500 km zonal distance. Here, we can characterize the PRVD with the peak value (v p ), the minimum value (v m ), and the amplitude Figure 1 as reported by Fejer et al [1991] and Abdu et al [2010].…”

Section: Nature Of U Ytmentioning

confidence: 99%

“…According to Huang and Kelley [1996b], this longitudinal feature can be modeled as a quasiGaussian electric field or vertical drift with pulse width about a 2000 km full width at half maximum which also travels westward with the terminator. For example, during very high (high) solar flux period, F10.7 > 200 (F10.7 200), the PRVD typically varies as a quasi-Gaussian shape with minimum 20 m/s to maximum 60 m/s within 1 h (1.5 h) effectively corresponds to approximately 1500 km (2000 km) longitudinal scale across the terminator [Fejer et al, 1991;Abdu et al, 2010].…”

Section: Introductionmentioning

confidence: 99%

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A numerical simulation study of the collisional‐interchange instability seeded by the pre‐reversal vertical drift

2013

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[1] The collisional interchange instability (CII) is known to lead to the equatorial plasma bubble (EPB) development when the ionosphere is raised to higher altitudes by the prereversal electric field or vertical drift (PRVD). The PRVD presents considerable longitudinal variation (with scale size 15 ı ) across the sunset terminator and this variation may act as a seeding perturbation as proposed by Woodman (1994) and Huang and Kelley (1996b). In the present work, we examine the efficiency of this longitudinal variation of the PRVD to act as a seeding for the CII and to give rise to EPB in the absence of any other kind of initial perturbation. To do so, we carried out the CII simulation at the equator in a plane perpendicular to the magnetic field. We consider a few simplified cases choosing a Gaussian-shaped longitudinal variation of PRVD with various possible minimum and peak values and finally consider a realistic case with a spatial-temporal configuration of PRVD obtained using SAMI2 model. Simulations with simplified cases show that the EPB develops only for minimum value greater than 20 m/s and amplitude (difference between the peak-to-minimum value) greater than 40 m/s. Simulation with a realistic case shows that the PRVD during high solar flux summer satisfies these threshold conditions and with the seeding scale 15 ı , the EPB of longitudinal size 2 ı is developed toward east of the PRVD peak.Citation: Sousasantos, J., E. A. Kherani, and J. H. A. Sobral (2013), A numerical simulation study of the collisional-interchange instability seeded by the pre-reversal vertical drift,

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Section: Discussionmentioning

confidence: 99%

Section: Simulation With Realistic Ionospheric Dynamics Obtained mentioning

confidence: 99%

Section: Nature Of U Ytmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A numerical simulation study of the collisional‐interchange instability seeded by the pre‐reversal vertical drift

2013

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“…Tsunoda (1985) shows that the ionospheric irregularity occurrence is a maximum when sunsets in the conjugate Eregion are simultaneous. Simultaneous sunset is expected to intensify the so-called PRE (Abdu et al, 1981(Abdu et al, , 1992(Abdu et al, , 2010Batista et al, 1986), a favorable and sufficient condition for the initiation of RTI. The angle between the geomagnetic meridian and the sunset terminator line was introduced as a proxy of the simultaneous sunset in the conjugate points (Burke et al, 2004).…”

Section: Discussion and Summarymentioning

confidence: 99%

A comparison of the equatorial spread F derived by the International Reference Ionosphere and the S 4 index observed by FORMOSAT-3/COSMIC during the solar minimum period of 2007–2009

et al. 2012

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The latest version of the International Reference Ionosphere (IRI-2007) model includes an option for spread-F occurrence prediction for the first-time. The IRI-2007 spread-F occurrence is a function of solar 10.7 cm radiation flux, F 10.7 . In this paper, an attempt is made to cross-examine the spread-F occurrence derived by the IRI-2007 and the ionospheric scintillations in terms of the maximum value of the S 4 index (S 4max ) between 150-350-km altitudes, calculated from fluctuations of the signal-to-noise ratio (SNR) intensity in the L1 channel of GPS radio occultation signals using FORMOSAT-3/COSMIC (F3/C) satellites during the low solar activity years [2007][2008][2009]. It is found that S 4max maintains a fairly good consistency with spread-F occurrence simulated by IRI-2007 in the Brazilian region. Thus, the global S 4 index statistics can be considered as a viable source of database to be incorporated into the global IRI spread-F prediction scheme owing to fact that the F3/C satellites can provide an unprecedented global database including the S 4 index.

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Longitudinal variation in Global Navigation Satellite Systems TEC and topside ion density over South American sector associated with the four‐peaked wave structures

et al. 2013

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[1] Recent observations of the low-latitude ionospheric electron density revealed a four-peaked longitudinal structure in the equatorial ionization anomaly when plotted at a constant-local-time frame. It was proposed that neutral wind-driven E region dynamo electric fields due to nonmigrating tidal modes are responsible for this pattern. We examine the four-peaked structure in the observed topside ion density and its manifestation as longitudinal structures in total electron content (TEC) over South America. The strong longitudinal variation in TEC characterized by larger value over Brazilian eastern longitude sector as compared to that over the Peruvian western longitude is modeled using the Sheffield University plasmasphere-ionosphere model (SUPIM) aiming to identify the control factors responsible for the longitude variation. We found that the SUPIM runs using as input the existing standard models of vertical drift, and thermospheric winds do not explain the TEC longitudinal structure. Realistic values of these control parameters were generated based on the strong vertical drift longitudinal variation as determined from magnetometer and Digisonde data and appropriately adjusted winds (horizontal wind model). These realistic vertical drifts together with the modified thermospheric wind, when used as input to the SUPIM, are found to satisfactorily explain the longitudinal differences in the TEC and topside ion density (Ni) over South America. The study shows that the TEC in the whole latitude distribution is larger over the east coast than over the west coast of South America and that the vertical drift and thermospheirc winds control the longitudinal four wave structure in the TEC and Ni.

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Solar flux effects on the equatorial evening vertical drift and meridional winds over Brazil: A comparison between observational data and the IRI model and the HWM representations

Cited by 27 publications

References 38 publications

A numerical simulation study of the collisional‐interchange instability seeded by the pre‐reversal vertical drift

A numerical simulation study of the collisional‐interchange instability seeded by the pre‐reversal vertical drift

A comparison of the equatorial spread F derived by the International Reference Ionosphere and the S 4 index observed by FORMOSAT-3/COSMIC during the solar minimum period of 2007–2009

Longitudinal variation in Global Navigation Satellite Systems TEC and topside ion density over South American sector associated with the four‐peaked wave structures

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