Solar activity variations of equatorial spread F occurrence and sustenance during different seasons over Indian longitudes: Empirical model and causative mechanisms

Haridas, M.; Manju, G.; Arunamani, T.

doi:10.1016/j.asr.2018.02.040

Cited by 10 publications

(3 citation statements)

References 22 publications

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“…These irregularities are a major space weather issue because they can degrade navigational signals, disrupt satellite to ground communications and cause large positioning errors. Ionospheric irregularities depend on local time, season, latitude, longitude, solar, and geomagnetic activity (Abdu, 2012;Madhav Haridas et al, 2018;Tsunoda, 2006). At equatorial and low latitudes, the gravitational Rayleigh-Taylor instability mechanism generates the ionospheric irregularities (Balsley et al, 1972;Dungey, 1956).…”

Section: Introductionmentioning

confidence: 99%

Ionospheric irregularities during disturbed geomagnetic conditions over Argentinian EIA region

González

2022

Acta Geod Geophys

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Ionospheric irregularities can severely degrade radio communication and navigation systems.Geomagnetic storms may affect the generation of these irregularities in a way that is not yet fully understood. To improve the forecasting of this phenomenon, we need to study the ionosphere in different regions of the world, and in particular in the equatorial ionization anomaly (EIA) where irregularities are usually more intense. This study analyses the effect of geomagnetic storms on ionospheric irregularities. We examined the occurrence of irregularities at the southern crest of the EIA in Argentina (Tucumán, 26.9°S, 294.6°E, dip latitude 15.5° S) during three intense and one moderate geomagnetic storm of different solar sources, between 2015 and 2018. We used data from an ionosonde, a Global Positioning System (GPS) receiver and magnetometers. Ionogram spread-F, the F-layer bottom side (h'F), the critical frequency of the F2-layer (foF2), the rate of TEC index (ROTI) and the S4 scintillation index were analysed. The data show irregularities were present as range spread-F and moderate TEC uctuations in one storm: 27 May 2017 (a coronal mass ejection CME-driven storm occurred on local winter), and were absent in the other events. We suggest that eastward disturbance dynamo electric eld and over-shielding prompt penetration electric elds may create favourable conditions for developing these irregularities. Whereas, westward storm time electric elds might inhibit the growth of irregularities during the other storms considered. During co-rotating interaction region CIR-driven storms, the westward disturbance dynamo electric eld may be associated with the non-occurrence of irregularities.

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Section: Introductionmentioning

confidence: 99%

Ionospheric irregularities during disturbed geomagnetic conditions over Argentinian EIA region

González

2022

Acta Geod Geophys

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“…The appreciable scatter observed in the correlation analysis (Figures 8 and 10) shows that in addition to the PW activity, there are still other factors that affect the ESF characteristic parameters. Madhav Haridas et al (2018) showed that ESF duration is linked to the growth rate of R‐T instability.…”

Section: Discussionmentioning

confidence: 99%

“…The lifetime of ESF irregularities depends on their original strength and the recombination rate. The irregularity strength increases with altitude, and correspondingly the recombination rate decreases (Madhav Haridas et al, 2018). On a day when postsunset base height increase associated with PW activity occurs, the recombination rates prevalent at those heights are lower, thereby facilitating the sustenance of the irregularities for longer duration.…”

Section: Discussionmentioning

confidence: 99%

Ionospheric Planetary Wave Activity and Its Role in Equatorial Spread F Day‐to‐Day Variability

Manju

Aswathy

2020

JGR Space Physics

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A comprehensive analysis on the ionospheric planetary wave activity is undertaken using 8 years of ionosonde data at Trivandrum (8.5°N, 77°E), a dip equatorial station. The study reveals that the dominant planetary wave is of 16-day type and its strength is maximum in winter solstice/autumnal equinox and minimum in summer solstice in high solar activity conditions. In low solar activity years planetary wave activity strength is more or less comparable in vernal equinox, autumnal equinox, and winter solstice, while it is observed to be least in summer solstice. Further, the planetary wave activity shows direct correlation with solar activity for the different seasons. Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite observations of off-equatorial E-region zonal winds confirm the fact that they are strong westward in high solar activity years compared to low solar activity years. The strong westward winds aid the upward propagation of westward propagating planetary waves in high solar activity years. Planetary waves reaching the off-equatorial E-region modulate the equatorial F-region via the coupling along the magnetic field lines. The role of planetary waves in modulating the pre-reversal enhancement, equatorial spread F duration, and its spread range on a day-today basis is brought out quantitatively for both high and low solar activity conditions. The study emphasizes the importance of ionospheric planetary wave studies for the prediction of equatorial spread F characteristics.

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A method for automatic detection of equatorial spread-F in ionograms

Scotto

Ippolito

Sabbagh

2019

Advances in Space Research

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Solar activity variations of equatorial spread F occurrence and sustenance during different seasons over Indian longitudes: Empirical model and causative mechanisms

Cited by 10 publications

References 22 publications

Ionospheric irregularities during disturbed geomagnetic conditions over Argentinian EIA region

Ionospheric irregularities during disturbed geomagnetic conditions over Argentinian EIA region

Ionospheric Planetary Wave Activity and Its Role in Equatorial Spread F Day‐to‐Day Variability

A method for automatic detection of equatorial spread-F in ionograms

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