A comparative study of GPS ionospheric scintillations and ionogram spread F over Sanya

Zhang, Y.; Wan, Weixing; Li, G.; Liu, Libo; Hu, Li-Peng; Ning, Baiqi

doi:10.5194/angeo-33-1421-2015

Cited by 12 publications

(11 citation statements)

References 50 publications

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“…In addition, the spread F occurrence and its global distribution are studied from F3/C satellite data, particularly from the occultation measurements of the GPS signal scintillation. This investigation is similar to a local study of spread F and scintillations over Sanya by Zhang et al (2015), who showed that spread F and large scintillations occur simultaneously. As the second objective, we verify that the new method of spread F velocity measurements based on continuous Doppler sounding gives values consistent with previously published results based on different methods of measurement and that these values properly describe the reported longitudinal differences.…”

Section: Introductionsupporting

confidence: 88%

Spread F occurrence and drift under the crest of the equatorial ionization anomaly from continuous Doppler sounding and FORMOSAT-3/COSMIC scintillation data

et al. 2016

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A relatively new method based on measurements by multipoint continuous Doppler sounding is applied to study the occurrence rate, propagation velocities, and directions of spread F structures over Tucumán, Northern Argentina, and Taiwan, both of which were under the crest of the equatorial ionization anomaly in 2014. In addition, spread F is studied globally over the same time period from the S4 scintillation index measured onboard FORMOSAT-3/COSMIC (F3/C) satellite. It is shown that the continuous Doppler sounding gives results that are consistent with S4 data and with previous optical, global positioning system (GPS), and satellite measurements. Most of the spread F events were observed from September to March, i.e., during the local summer half of the year in Tucumán, whereas in Taiwan, the highest occurrence rate was observed around equinoxes. The occurrence rate in Tucumán was about four times higher than that in Taiwan. The propagation velocities and directions were estimated from the Doppler shift spectrograms. The spread structures related to spread F propagated roughly eastward at velocities from ~70 to ~200 m s −1 during nighttime hours. The mean observed horizontal velocity was 140 m s −1 over Tucumán and 107 m s −1 over Taiwan. The local times at which the highest velocities were observed roughly correspond to local times with highest values of scintillation index S4, at ~20 to 23 LT. In addition, a comparison of measured drift velocities with neutral wind velocities predicted by models is provided. The observed velocities usually exceeded the horizontal neutral wind velocities predicted by the HWM14 model for the locations and times of observations.

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Section: Introductionsupporting

confidence: 88%

Spread F occurrence and drift under the crest of the equatorial ionization anomaly from continuous Doppler sounding and FORMOSAT-3/COSMIC scintillation data

et al. 2016

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“…Also, the FSF occurrences observed at different sites exhibited distinct local time distribution patterns. Previous studies have also observed this trend (Zhang et al 2015;de Jesus et al 2010de Jesus et al , 2016 Figure 6 shows variations in the average RSF occurrence rates at the four sites. The RSF occurrence rate was much larger than the FSF occurrence rate at GZ; however, the rates were smaller than the FSF occurrence rates at BJ and CC.…”

Section: Nocturnal Seasonal and Solar Activity Variations On Spreadsupporting

confidence: 72%

Spread-F occurrences and relationships with foF2 and h′F at low- and mid-latitudes in China

Wang

Guo

Zhao

et al. 2018

Earth Planets Space

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Ionospheric irregularities are an important phenomenon in scientific studies and applications of radio-wave propagation. Spread-F echoes in ionograms are a type of high-frequency band irregularities that include frequency spread-F (FSF), range spread-F (RSF), and mixed spread-F (MSF) events. In this study, we obtained spread-F data from four ionosondes at low-and mid-latitudes near the 120°E chain in China during the 23rd solar cycle. We used these data to investigate spread-F occurrence percentages and variations with local time, season, latitude, and solar activity. The four ionosondes were located at Haikou (HK) (20°N, 110.34°E), Guangzhou (GZ) (23.14°N, 113.36°E), Beijing (BJ) (40.11°N, 116.28°E), and Changchun (CC) (43.84°N, 125.28°E). We also present possible correlations between spread-Fs and other ionospheric parameters, such as the critical frequency of the F2-layer (foF2) and the virtual height of the bottom-side F-layer (h′F). In particular, we investigated the possible threshold of the foF2 affecting the FSF and the relationship between the h′F and the RSF. The main conclusions are as follows: (a) the FSF occurrence percentages were anti-correlated with solar activity at all four sites; meanwhile, RSF occurrence rates increased with the increase in solar activity at HK, but not at the other three sites; (b) FSF occurrence rates were larger at the mid-latitudes than expected, while FSFs occurred more often after midnight; (c) the highest FSF occurrence rates mostly appeared during the summer months, while RSFs occurred mostly in the equinoctial months of 2000-2002 at HK and GZ; (d) a lower foF2 was suitable for FSF events; nevertheless, h′F and RSF occurrences satisfied the parabolic relationship; (e) the foF2 thresholds for FSFs were 15, 14, 7.6, and 7.8 MHz at HK, GZ, BJ, and CC, respectively. The h′Fs occurring between 240 and 290 km were more favorable for RSF occurrences. These results are important for understanding ionospheric irregularity variations in eastern Asia and for improving space weather modeling and forecasting capabilities .

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“…To display ionograms, both the raw and processed (SAO) data were loaded into the SAO Explorer software. In addition, the spread-F index QF, known as the mean spread of the diffusing F layer trace, was obtained by the ARTIST directly from the ionograms using the SAO explorer (Galkin et al, 2008;Zhang et al, 2015) and this was also used in this study to analyze the spread-F signatures. The mean range spread refers to the averaged spread range of all frequencies that detect a diffuse echo in an ionogram (Zhang et al, 2015).…”

Section: Ground-based Ionospheric Irregularity Identificationmentioning

confidence: 99%

“…In addition, the spread-F index QF, known as the mean spread of the diffusing F layer trace, was obtained by the ARTIST directly from the ionograms using the SAO explorer (Galkin et al, 2008;Zhang et al, 2015) and this was also used in this study to analyze the spread-F signatures. The mean range spread refers to the averaged spread range of all frequencies that detect a diffuse echo in an ionogram (Zhang et al, 2015). The spread range at each frequency is the virtual height difference between the top and bottom of the spread echo at a particular frequency (Abdu et al, 2012;Zhang et al, 2015).…”

Section: Ground-based Ionospheric Irregularity Identificationmentioning

confidence: 99%

“…The mean range spread refers to the averaged spread range of all frequencies that detect a diffuse echo in an ionogram (Zhang et al, 2015). The spread range at each frequency is the virtual height difference between the top and bottom of the spread echo at a particular frequency (Abdu et al, 2012;Zhang et al, 2015). The QF is assigned to NaN (not a number) if there is no spread F observed in an ionogram (Zhang et al, 2015).…”

Section: Ground-based Ionospheric Irregularity Identificationmentioning

confidence: 99%

See 1 more Smart Citation

Simultaneous Ground-based and In Situ Swarm Observations of Equatorial F-region Irregularities over Jicamarca

Aol¹,

Buchert²,

Jurua³

et al. 2019

Preprint

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Abstract. Ionospheric irregularities are a common phenomenon in the low latitude ionosphere. They can be seen in situ as depletions of plasma density, radar plasma plumes or ionogram spread F by ionosondes. In this paper, we compared simultaneous observations of plasma plumes by the Jicamarca unattended long term investigations of the ionosphere and atmosphere (JULIA) radar, ionogram spread F generated from ionosonde observations installed at the Jicamarca Radio Observatory (JRO), and irregularities observed in situ by Swarm, to determine whether Swarm in situ observations can be used as indicators of the presence of plasma plumes and spread-F on the ground. The study covered the years from 2014 to 2018 when all the data-sets were available. Overall, the results showed that Swarm's in situ density fluctuations on magnetic flux tubes passing over (or near) the JRO may be used as indicators of plasma plumes and spread-F over (or near) the observatory. For Swarm and the ground-based observations, a classification procedure was conducted based on the presence or absence of ionospheric irregularity structures. There was a strong consensus between ground-based observations of irregularity structures and Swarm's depth of disturbance of electron density for most passes. Cases, where irregularity structures were observed on the ground with no apparent variation in the in situ electron density or vice versa, suggest that irregularities may either be localized horizontally or restricted to particular height intervals. The results also showed that the Swarm and ground-based observations of ionospheric irregularities had similar local time statistical trends with the highest occurrence obtained between 20:00 and 22:00 LT. Also, similar seasonal patterns of occurrence of in situ and ground-based ionospheric irregularities were observed with the highest percentage occurrence in December Solstice and Equinoxes and low occurrence in June Solstice. The observed seasonal pattern was explained in terms of the pre-reversal enhancement (PRE) of the vertical plasma drift. Initial findings from this research indicate that fluctuations of in situ density observed meridionally along magnetic field lines passing through JRO can be used as an indication of the existence of well-developed plasma plumes.

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A comparative study of GPS ionospheric scintillations and ionogram spread F over Sanya

Cited by 12 publications

References 50 publications

Spread F occurrence and drift under the crest of the equatorial ionization anomaly from continuous Doppler sounding and FORMOSAT-3/COSMIC scintillation data

Spread F occurrence and drift under the crest of the equatorial ionization anomaly from continuous Doppler sounding and FORMOSAT-3/COSMIC scintillation data

Spread-F occurrences and relationships with foF2 and h′F at low- and mid-latitudes in China

Simultaneous Ground-based and In Situ Swarm Observations of Equatorial F-region Irregularities over Jicamarca

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