Nighttime lower ionosphere height estimation from the VLF modal interference distance

Samanes, Jorge; Raulin, J. P.; Cao, Jinbin; Magalhães, Antonio

doi:10.1016/j.jastp.2017.10.009

Cited by 9 publications

(8 citation statements)

References 52 publications

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“…The ionosphere height arose to about 100 km, 5-10 km higher than its surrounding areas from June to August, at latitudes of about ±30 • and longitudes between 90 • and 150 • . Samanes [38] studied its nighttime features at the equatorial region for the western longitudes by using data from the DEMETER satellite and ground VLF receivers, and they found typical seasonal characteristics with lower values in winter time compared to summer time. The effective height in the Indonesia seismic area, as derived in our study, should increase or maintain a relatively high value during July and August, according to [37] and [38].…”

Section: Discussionmentioning

confidence: 99%

Multi-Experiment Observations of Ionospheric Disturbances as Precursory Effects of the Indonesian Ms6.9 Earthquake on August 05, 2018

et al. 2020

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Taking the 2018 Ms6.9 Indonesia earthquake as a case study, the ionospheric perturbations in very low frequency (VLF) transmitters recorded by China Seismo-Electromagnetic Satellite (CSES) were mainly investigated, as well as the multi parameters of the plasma and electromagnetic field. The characteristics of electron density (Ne), GPS TEC, ULF electric field, ion drift velocity, and ionosphere height were extracted and compared with the features of the signal-noise ratio (SNR) from VLF transmitters of NWC at the southern hemisphere and JJI at the northern hemisphere. Most disturbances in VLF radio waves occurred along the orbits near the epicenter within 10 days before the earthquake. Along these orbits, we observed simultaneous modulations in the Ne and ULF electric field, as well as the changed ion drifting directions. There was also high spatial correspondence between both SNR and ionospheric height anomalies over the epicentral and its magnetic conjugate regions. Combined with the multi observations, these results suggest that the genesis of perturbations in signals emitted by VLF transmitters on satellite was more likely related to the overlapped electric field in the preparation area of the earthquake.

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Section: Discussionmentioning

confidence: 99%

Multi-Experiment Observations of Ionospheric Disturbances as Precursory Effects of the Indonesian Ms6.9 Earthquake on August 05, 2018

et al. 2020

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“…However, the findings of Sharma et al () did agree with Silber et al () that the SAO is the strongest oscillation detected in midlatitude nighttime VLF measurements. Using the Lomb‐Scargle method, periodicities related to the AO, SAO, and quasi biennial oscillation were reported by Samanes et al (). They analyzed the derived nighttime reflection height using signals that propagated in low‐latitude regions.…”

Section: Introductionmentioning

confidence: 96%

“…Periodic variations of solar (Demirkol et al, ; Thomson & Clilverd, ) and terrestrial (Samanes et al, ) origin affect recorded VLF signals over long‐ or short‐time scales. Many studies show long‐term periodic variations of solar origin, such as the 11‐year solar cycle, in the lower ionosphere (e.g., Macotela et al, ; Thomson & Clilverd, ).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have reported the influence of the annual oscillation (AO) and semiannual oscillation (SAO) using ground‐based VLF narrowband measurements (Samanes et al, ; Sharma et al, ; Silber et al, ). Silber et al () applied the Lomb‐Scargle method to recorded VLF signals that had propagated in low‐latitude and midlatitude regions, to determine the dominant oscillations in the nighttime VLF measurements.…”

Section: Introductionmentioning

confidence: 99%

“…Very low frequency (VLF: 3–30 kHz) radio signals propagate inside the Earth‐ionosphere waveguide and can be used to monitor the electrical conductivity of the waveguide's upper boundary (Wait & Spies, ). This upper boundary fluctuates in the altitude range ~60–90 km from day to night and is known as the D‐region (Hargreaves, ; Samanes et al, ). The lower ionosphere can be affected by sporadic (Bracewell & Straker, ) or periodic (McWilliams & Strait, ) external forces.…”

Section: Introductionmentioning

confidence: 99%

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D‐Region High‐Latitude Forcing Factors

et al. 2019

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The subionospheric very low frequency (VLF) radio wave technique provides the possibility of investigating the response of the ionospheric D‐region to a diversity of transient and long‐term physical phenomena originating from above (e.g., energetic particle precipitation) and from below (e.g., atmospheric waves). In this study, we identify the periodicities that appear in VLF measurements and investigate how they may be related to changes in space weather and atmospheric activity. The powerful VLF signal transmitted from NAA (24 kHz) on the east coast of the United States, and received at Sodankylä, Finland, was analyzed. Wavelet transform, wavelet power spectrum, wavelet coherence, and cross‐wavelet spectrum were computed for daily averages of selected ionospheric, space weather, and atmospheric parameters from November 2008 until June 2018. Our results show that the significant VLF periods that appear during solar cycle 24 are the annual oscillation, semiannual oscillation, 121‐day, 86‐day, 61‐day, and solar rotation oscillations. We found that the annual oscillation corresponds to variability in mesospheric temperature and solar Lyman‐α (Ly‐α) flux and the semiannual oscillation to variability in space weather‐related parameters. The solar rotation oscillation observed in the VLF variability is mainly related to the Ly‐α flux variation at solar maximum and to geomagnetic activity variation during the declining phase of the solar cycle. Our results are important since they strengthen our understanding of the Earth's D‐region response to solar and atmospheric forcing.

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Periodic Oscillation of VLF Transmitter Signals Measured in Low and Middle Latitude Regions

Xu,

Feng,

et al. 2024

JGR Atmospheres

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Measurements of Very Low Frequency (VLF) signals from navy transmitters carry direct information about the D‐region ionosphere and have been widely utilized for detecting the electron density at D‐region altitudes, but not frequently for the atmospheric waves therein. Atmospheric waves have been extensively studied using the total ionospheric electron content, but if and how they are correlated with the D‐region ionosphere and VLF measurements still remains poorly investigated. In this study, we have conducted a comprehensive analysis using 7‐year measurements (2016–2022) of VLF signals from the JJI, NWC, and VTX transmitters as being recorded in Suizhou, China. These three transmitter‐receiver paths are representative and the corresponding observations constitute a valuable data set to investigate the periodicities of VLF data. Different from previous studies, we have utilized the ensemble empirical mode decomposition and Lomb‐Scargle methods to determine the periodicities of these data. By contrasting these paths, prominent periodicities ranging from 2 to 730 days have been found, with clear diurnal variation and suggestive latitudinal/longitudinal dependence. Moreover, we have found that the mesospheric temperature is closely related with the annual oscillation of VLF measurements, while this oscillation has a low correlation with solar Lyman‐α fluxes or geomagnetic activity. The oscillations with relatively shorter periods are likely atmospheric waves such as gravity waves, planetary waves, or harmonics of these waves. Our results suggest that, in addition to the electron density, the subionospheric VLF technique can be potentially utilized to remotely sense atmospheric waves that propagate up to or through the D‐region ionosphere.

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Nighttime lower ionosphere height estimation from the VLF modal interference distance

Cited by 9 publications

References 52 publications

Multi-Experiment Observations of Ionospheric Disturbances as Precursory Effects of the Indonesian Ms6.9 Earthquake on August 05, 2018

Multi-Experiment Observations of Ionospheric Disturbances as Precursory Effects of the Indonesian Ms6.9 Earthquake on August 05, 2018

D‐Region High‐Latitude Forcing Factors

Periodic Oscillation of VLF Transmitter Signals Measured in Low and Middle Latitude Regions

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