Solar flare induced ionospheric D-region perturbation as observed at a low latitude station Agra, India

Pandey, Uma; Singh, Birbal; Singh, O. P.; Saraswat, Vibhav K.

doi:10.1007/s10509-015-2279-6

Cited by 9 publications

(19 citation statements)

References 22 publications

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“…They found that VLF phase and reflection height changes do not have a linear proportion to the logarithm of the solar X-ray flux, in agreement with some studies [e.g., Selvakumaran et al, 2015], in contradiction to others [e.g., Pacini and Raulin, 2006;Pandey et al, 2015]. By using the LWPC model they determined that such a strong flare can be explained by 13 km and 0.13 km -1 reflection height and electron density slope changes, respectively.…”

Section: Space Weather Phenomena and Eclipsessupporting

confidence: 70%

“…That flare's magnitude was approximated to be X45 [Thomson et al, 2004], based on the conclusions of McRae and . Other studies have also examined the reflection height, electron density slope, and vertical profile modifications, due to various classes of solar flares, and obtained different parameter values, possibly due to different latitude range and lengths of the TRGCPs [e.g., Kaufmann and Mendes, 1968;Kamada, 1985;Žigman et al, 2007;Grubor et al, 2008;Schmitter, 2013;Grubor, 2014, 2015;Pandey et al, 2015;Šulić et al, 2016]. These calculated values had a large variance, and a few of them [e.g., Kamada, 1985;Grubor et al, 2008] reached magnitudes which were comparable to those deduced by Thomson et al [2005].…”

Section: Space Weather Phenomena and Eclipsesmentioning

confidence: 99%

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On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

Silber

Price

2016

Surv Geophys

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The ionospheric D-region (~60 km up to ~95 km) and the corresponding neutral atmosphere, often refered to as the mesosphere-lower-thermosphere (MLT) are challenging and costly to probe in-situ. Therefore, remote sensing techniques have been developed over the years. One of these is based on VLF (Very low frequency, 3-30 kHz) electromagnetic waves generated by various natural and manmade sources. VLF waves propagate within the Earth-ionosphere waveguide, and are extremely sensitive to perturbations occurring in the D-region along their propagation path. Therefore, measurements of these signals serve as an inexpensive remote sensing technique for probing the lower ionosphere and the MLT region. This paper reviews the use of VLF narrowband (NB) signals (generated by man-made transmitters) in the study of the D-region and the MLT for over 90 years. The fields of research span time scales from microseconds to decadal variability, and incorporate lightning-induced short term perturbations; extraterrestrial radiation bursts; energetic particle precipitation events; solar eclipses; lower atmospheric waves penetrating into the D-region; sudden stratospheric warming events; the annual oscillation; the solar cycle; and finally, the potential use of VLF NB measurements as an anthropogenic climate change monitoring technique.

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Section: Space Weather Phenomena and Eclipsessupporting

confidence: 70%

Section: Space Weather Phenomena and Eclipsesmentioning

confidence: 99%

On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

Silber

Price

2016

Surv Geophys

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“…Figure 13 gives the simple dependence for H' with the well-defined slope Looking at the Figure 13, one can see a totally different situation for the results of It can be noticed that, when the intense solar flux increases during SF, values of the reflection height H' decrease. Looking at Figure 12, generally speaking, there is a good agreement in the values of the reflection height from the literature [41][42][43][44]. When the intensity of radiation increases from 10 −6 to 10 −3 Wm −2 (i.e., when we go from normal conditions of the ionosphere to the perturbed ionosphere due to strong X-class SF), the reflections go down from 74 km to 50 km.…”

Section: Comparison Of Obtained Ionospheric Parameterssupporting

confidence: 58%

“…The sharpness parameter β and reflection height H' (red squares) calculated in present work are plotted in Figures 12 and 13 together with results of other authors [41][42][43][44]. In Table S3, one can find the data of amplitude and phase perturbations of the VLF signal and the ionospheric parameters induced by different SF events which were also analyzed in this study.…”

Section: Comparison Of Obtained Ionospheric Parameterssupporting

confidence: 56%

Low Ionosphere under Influence of Strong Solar Radiation: Diagnostics and Modeling

et al. 2021

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Solar flares (SFs) and intense radiation can generate additional ionization in the Earth’s atmosphere and affect its structure. These types of solar radiation and activity create sudden ionospheric disturbances (SIDs), affect electronic equipment on the ground along with signals from space, and potentially induce various natural disasters. Focus of this work is on the study of SIDs induced by X-ray SFs using very low frequency (VLF) radio signals in order to predict the impact of SFs on Earth and analyze ionosphere plasmas and its parameters. All data are recorded by VLF BEL stations and the model computation is used to obtain the daytime atmosphere parameters induced by this extreme radiation. The obtained ionospheric parameters are compared with results of other authors. For the first time we analyzed physics of the D-region—during consecutive huge SFs which continuously perturbed this layer for a few hours—in detail. We have developed an empirical model of the D-region plasma density and gave a simple approximative formula for electron density.

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“…In Figure 14, we present the results from this investigation, i.e., paper (using three methods from Sections 2.2.1-2.2.3), which are either simulated, calculated, approximated or the data obtained from literature [16,37,[40][41][42], for electron density N e at reference height as a function of X-ray flux. The area of importance is between the two red lines.…”

Section: Comparison Of Resultsmentioning

confidence: 99%

Novel Modelling Approach for Obtaining the Parameters of Low Ionosphere under Extreme Radiation in X-Spectral Range

et al. 2021

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Strong radiation from solar X-ray flares can produce increased ionization in the terrestrial D-region and change its structure. Moreover, extreme solar radiation in X-spectral range can create sudden ionospheric disturbances and can consequently affect devices on the terrain as well as signals from satellites and presumably cause numerous uncontrollable catastrophic events. One of the techniques for detection and analysis of solar flares is studying the variations in time of specific spectral lines. The aim of this work is to present our study of solar X-ray flare effects on D-region using very low-frequency radio signal measurements over a long path in parallel with the analysis of X-spectral radiation, and to obtain the atmospheric parameters (sharpness, reflection height, time delay). We introduce a novel modelling approach and give D-region coefficients needed for modelling this medium, as well as a simple expression for electron density of lower ionosphere plasmas. We provide the analysis and software on GitHub.

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Solar flare induced ionospheric D-region perturbation as observed at a low latitude station Agra, India

Cited by 9 publications

References 22 publications

On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

Low Ionosphere under Influence of Strong Solar Radiation: Diagnostics and Modeling

Novel Modelling Approach for Obtaining the Parameters of Low Ionosphere under Extreme Radiation in X-Spectral Range

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