Development of intermediate scale structure near the peak of the <i>F</i> region within an equatorial plasma bubble

Bhattacharyya, A.; Kakad, Bharati; Sripathi, S.; Jeeva, K.; Nair, K. U.

doi:10.1002/2013ja019619

Cited by 23 publications

(33 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the same time above the F peak at the equatorial station the irregularity spectrum is shallower as small‐scale irregularity develops there before midnight [ Bhattacharyya et al , ]. These irregularities map down to off equatorial stations.…”

Section: Resultsmentioning

confidence: 99%

Structuring of intermediate scale equatorial spread F irregularities during intense geomagnetic storm of solar cycle 24

et al. 2016

Self Cite

View full text Add to dashboard Cite

Here we examine the structuring of equatorial plasma bubble (EPB) during intense geomagnetic storm of solar cycle (SC) 24 that occurred on 17 March 2015 using spaced receiver scintillation observations on a 251 MHz radio signal, recorded by a network of stations in Indian region. As yet, this is the strongest geomagnetic storm (Dstmin∼−223nT) that occurred in present SC. Present study reveals that the structuring of equatorial spread F (ESF) irregularities was significantly different on 17 March as compared to quiet days of corresponding month. ESF irregularities of intermediate scale (100 m to few kilometers) are observed at unusually higher altitudes (≥ 800 km) covering wider longitudinal‐latitudinal belt over Indian region. A presence of large‐scale irregularity structures with stronger ΔN at raised F peak with small‐scale irregularities at even higher altitudes is observed. It caused strong focusing effect (S4>1) that prevails throughout premidnight hours at dip equatorial station Tirunelveli. Other observational aspect is that zonal irregularity drifts over low‐latitude station Kolhapur exhibited a large deviation of ∼230 m/s from their average quiet time pattern. During this geomagnetic storm, two southward turnings of significant strength (BZ≤−15 nT) occurred at 11.4 IST (Indian standard time) and 17.9 IST. The later southward turning of interplanetary magnetic field (IMF)BZ resulted in a large eastward prompt penetration electric field (PPEF) close to sunset hours in Indian longitude. Estimates of PPEF obtained from real‐time ionospheric model are too low to explain the observed large upliftment of F region in the post sunset hours. Possible reason for observed enhanced PPEF‐linked effects is discussed.

show abstract

Section: Resultsmentioning

confidence: 99%

Structuring of intermediate scale equatorial spread F irregularities during intense geomagnetic storm of solar cycle 24

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition, as the large-scale bubbles map down along geomagnetic field lines to off-equatorial latitudes, the spectrum of the intermediate-scale irregularities within the bubbles tends to become shallower near the F-region peak. This factor, based on the recent study of Bhattacharyya et al (2017), also contributes to the strong L-band scintillations observed near the crest of the EIA, particularly in years of high solar activity and during the December solstice months in the longitude of Cachoeira Paulista. Figure 1 also shows that the occurrence of scintillation started to subside with the decline in solar activity.…”

Section: Ionospheric Scintillation Climatologymentioning

confidence: 92%

“…Once the spatial distribution and strength of the scintillations are dominated by the background electron density, the most intense scintillations are expected to occur around 15-20 • from the magnetic equator at latitudes of the crests of the EIA. Moreover, the latitudinal variation in the intermediate-scale length (from hundreds of meters to a few kilometers) irregularity spectrum within a plasma bubble may also contribute to strong scintillations near the crests of the EIA (Bhattacharyya et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…The work of Aarons (1982) clearly depicts how the scintillation intensities, produced by the smaller-scale irregularity structures coexisting with the plasma bubbles, are maximized in the regions of the Appleton anomaly. More recently, relevant features of ionospheric radio-wave scintillations at the equatorial anomaly region have been extensively investigated for different longitudinal sectors (Spogli et al, 2013;Chatterjee and Chakraborty, 2013;Bhattacharyya et al, 2014;Akala et al, 2015;Cesaroni et al, 2015;Zhang et al, 2015;Srinivasu et al, 2016;Moraes et al, 2017). In the South American sector, particularly for the L-band frequencies, the occurrence characteristics of scintillation-producing irregularities have been demonstrated using ground-based global navigation satellite system (GNSS) receiver networks (e.g., de Akala et al, 2011;Muella et al, 2013Muella et al, , 2014.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Climatology and modeling of ionospheric scintillations and irregularity zonal drifts at the equatorial anomaly crest region

et al. 2017

View full text Add to dashboard Cite

Abstract. In this study the climatology of ionospheric scintillations and the zonal drift velocities of scintillationproducing irregularities are depicted for a station located under the southern crest of the equatorial ionization anomaly. Then, the α−µ ionospheric fading model is used for the firstand second-order statistical characterization of amplitude scintillations. In the statistical analyzes, data are used from single-frequency GPS receivers acquired during ∼ 17 years (September 1997-November 2014 at Cachoeira Paulista (22.4 • S; 45.0 • W), Brazil. The results reveal that the nocturnal occurrence of scintillations follows the seasonal distribution of plasma bubble irregularities observed in the longitudinal sector of eastern South America. In addition to the solar cycle dependence, the results suggest that the occurrence climatology of scintillations is also modulated by the secular variation in the dip latitude of Cachoeira Paulista, since the maximum occurrence of scintillations during the peak of solar cycle 24 was ∼ 20 % lower than that observed during the maximum of solar cycle 23. The dynamics of the irregularities throughout a solar cycle, as investigated from the estimates of the mean zonal drift velocities, presented a good correlation with the EUV and F10.7 cm solar fluxes. Meanwhile, the seasonal behavior showed that the magnitude of the zonal drift velocities is larger during the December solstice months than during the equinoxes. In terms of modeling, the results for the α − µ distribution fit quite well with the experimental data and with the temporal characteristics of fading events independently of the solar activity level.

show abstract

“…As discussed in Bhattacharyya et al . [], these results of Retterer [] indicate that prior to 22 h local time (LT), the power spectrum of VTEC fluctuations is shallowest in the EIA crest region at a geomagnetic latitude of ~16°. Since the maximum contribution to VTEC at any location comes from the F layer peak region, it could be concluded that for magnetic east‐west scale sizes down to 10 km, the equatorial F layer peak was less structured than that in the EIA crest region prior to 22 LT.…”

Section: Introductionmentioning

confidence: 99%

Development of intermediate‐scale structure at different altitudes within an equatorial plasma bubble: Implications for L‐band scintillations

et al. 2017

Self Cite

View full text Add to dashboard Cite

An important aspect of the development of intermediate‐scale length (approximately hundred meters to few kilometers) irregularities in an equatorial plasma bubble (EPB) that has not been considered in the schemes to predict the occurrence pattern of L‐band scintillations in low‐latitude regions is how these structures develop at different heights within an EPB as it rises in the postsunset equatorial ionosphere due to the growth of the Rayleigh‐Taylor instability. Irregularities at different heights over the dip equator map to different latitudes, and their spectrum as well as the background electron density determine the strength of L‐band scintillations at different latitudes. In this paper, VHF and L‐band scintillations recorded at different latitudes together with theoretical modeling of the scintillations are used to study the implications of this structuring of EPBs on the occurrence and strength of L‐band scintillations at different latitudes. Theoretical modeling shows that while S4 index for scintillations on a VHF signal recorded at an equatorial station may be >1, S4 index for scintillations on a VHF signal recorded near the crest of the equatorial ionization anomaly (EIA) generally does not exceed the value of 1 because the intermediate‐scale irregularity spectrum at F layer peak near the EIA crest is shallower than that found in the equatorial F layer peak. This also explains the latitudinal distribution of L‐band scintillations. Thus, it is concluded that there is greater structuring of an EPB on the topside of the equatorial F region than near the equatorial F layer peak.

show abstract

Development of intermediate scale structure near the peak of the F region within an equatorial plasma bubble

Cited by 23 publications

References 31 publications

Structuring of intermediate scale equatorial spread F irregularities during intense geomagnetic storm of solar cycle 24

Structuring of intermediate scale equatorial spread F irregularities during intense geomagnetic storm of solar cycle 24

Climatology and modeling of ionospheric scintillations and irregularity zonal drifts at the equatorial anomaly crest region

Development of intermediate‐scale structure at different altitudes within an equatorial plasma bubble: Implications for L‐band scintillations

Contact Info

Product

Resources

About