Long‐term 1.5 GHz amplitude scintillation measurements at the magnetic equator

Basu, S.; Mullen, J. P.; Bushby, A. J.

doi:10.1029/gl007i004p00259

Cited by 40 publications

(16 citation statements)

References 11 publications

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“…These aspects suggest that the Ionospheric-Atmospheric conditions over SLZ (CXI) are most (least) favourable for the generation of ESF, among three stations. ROJ has % occurrence characteristics more similar towards SLZ except that the season of maximum occurrence of ESF with plume is during equinox, which is a known feature from earlier studies (Basu et al, 1980;Sobral et al, 2002;de Paula et al, 2011). However, it is interesting to note that the season of maximum occurrence of all ESF events (i.e.…”

Section: Seasonal and Longitudinal Occurrences Of Spread F Parametersmentioning

confidence: 53%

Statistical analysis of radar observed F region irregularities from three longitudinal sectors

2013

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Abstract. Equatorial Spread F (ESF) is a manifestation of ionospheric interchange instabilities in the nighttime equatorial F region. These instabilities generate plasma density irregularities with scale sizes ranging from centimetres to thousands of kilometres. The irregularities can be detected from a variety of instruments such as digisonde, coherent and incoherent scatter radars, in situ space probes, and airglow photometers. In the present study, occurrence statistics of the ESF, based on various parameters are presented using data obtained from the VHF radars located at three longitudinally separated equatorial stations: Christmas Island (2 • N, 202.6 • E, 2.9 • N dip latitude), São Luís (2.59 • S, 315.8 • E, 0.5 • S dip latitude) and Jicamarca (12 • S, 283.1 • E, 0.6 • N dip latitude). The ESF parameters presented here are the onset altitude, onset time (onset refers to first appearance of signal in the radar field of view) of the bottom-type and plume, and the peak altitude of the plume. Recent studies have used these parameters to classify the spread F occurrence characteristics. The present study reveals novel features namely, the dependence of ESF parameters on the seasonal, solar flux, declination angle and longitudinal dependence from the three radar sites. In addition, we also present an empirical model to determine the nature of these ESF parameters as a function of the solar flux which may enable us to forecast (with 30 min to 1 h tolerance) the plume occurrence at any longitude located in between São Luís and Christmas Island.

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Section: Seasonal and Longitudinal Occurrences Of Spread F Parametersmentioning

confidence: 53%

Statistical analysis of radar observed F region irregularities from three longitudinal sectors

2013

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“…While the first two points above are expected from the known climatology of scintillation at L-band frequencies (Aarons and Basu, 1994;Basu et al, 1980), the third point, at first impression, seems to indicate that the peak activity is biased equator-ward from the anomaly crests by 2 • -3 • in magnetic latitude. However, this is not the case as the anomaly crests move equator-ward after the passage of the sunset terminator as displayed in Fig.…”

Section: Latitudinal Position Of Irregularity Activitymentioning

confidence: 97%

Latitudinal and temporal variation of equatorial ionospheric irregularities determined from GPS scintillation observations

Cervera

Thomas²

2006

Ann. Geophys.

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Abstract. In this paper we investigate the spatial and temporal distribution of ionospheric irregularities in the South-East Asian longitude sector by analysing the scintillation of GPS signals received at ground based stations. The data used for this work were collected during 1998 to 2002 with our regional network of GPS based scintillation monitors .The aim of this analysis is to better understand the morphology and climatology of ionospheric irregularities in our region. Interesting differences between the north and south anomalies are noted when we examine the latitudinaltemporal variation of irregularity activity. We investigate the possible causes of these differences and note that variations in the irregularity seeding mechanism and in the background ionosphere at the two anomalies could be important.Phase screen diffraction theory is used to analyse our scintillation data and we note problems with this theory for raypaths with large off-zenith angles. The height of the phase screen is another important issue. We discuss the implications for models which rely on phase screen diffraction theory.

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“…Previous studies found that ionospheric structures, such as the sporadic E (Es), equatorial plasma irregularities (EPIs), equatorial ionization anomaly (EIA), polar patches, and auroral blobs, can cause additional influence on the GNSS signal (e.g., Basu et al, 1980Basu et al, , 2002Crowley et al, 2000;Kintner et al, 2004Kintner et al, , 2007Yue et al, 2016). These ionospheric structures with spatial scales from hundreds of kilometers down to meters produce rapid fluctuations of the received signal phase and amplitude termed as scintillations.…”

Section: Introductionmentioning

confidence: 99%

“…Ionospheric scintillations from ground-based measurements have been widely used to investigate the morphology of the ionosphere (e.g., Basu et al, 1980;Aarons, 1982;Spogli et al, 2009;Jin et al, 2014;Clausen et al, 2016). Some low Earth orbit (LEO) missions, such as the CHAllenging Minisatellite Payload (CHAMP) and the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), were equipped with GPS radio occultation (RO) instruments with high temporal resolution, which have also been applied for investigating the morphology of Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

Climatology of GPS signal loss observed by Swarm satellites

2018

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Abstract. By using 3-year global positioning system (GPS) measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20 • magnetic latitude (MLAT) and high latitudes above 60 • MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the highlatitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20 • , and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver.

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Long‐term 1.5 GHz amplitude scintillation measurements at the magnetic equator

Cited by 40 publications

References 11 publications

Statistical analysis of radar observed F region irregularities from three longitudinal sectors

Statistical analysis of radar observed F region irregularities from three longitudinal sectors

Latitudinal and temporal variation of equatorial ionospheric irregularities determined from GPS scintillation observations

Climatology of GPS signal loss observed by Swarm satellites

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