A comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations

Lanyi, G. E.; Roth, Titus

doi:10.1029/rs023i004p00483

Cited by 295 publications

(203 citation statements)

References 5 publications

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“…Because elevation is mainly a geometrical effect, it should be possible to analytically "remove" its effects on the data. We do this with the commonly used "thin-shell" model of the ionosphere in which the ionosphere is approximated as very thin layer encircling the Earth at a constant height above the Earth's surface (Lanyi & Roth 1988;Ma & Maruyama 2003). In this model, the entire ionospheric phase delay of incoming radiation occurs at the "pierce-point" where the observing path to the celestial source intersects the ionospheric shell.…”

Section: Dependence On Elevationmentioning

confidence: 99%

Probing Fine-Scale Ionospheric Structure With the Very Large Array Radio Telescope

Cohen

Röttgering

2009

The Astronomical Journal

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High-resolution (∼1 arcmin) astronomical imaging at low frequency ( 150 MHz) has only recently become practical with the development of new calibration algorithms for removing ionospheric distortions. In addition to opening a new window in observational astronomy, the process of calibrating the ionospheric distortions also probes ionospheric structure in an unprecedented way. Here we explore one aspect of this new type of ionospheric measurement: the differential refraction of celestial source pairs as a function of their angular separation. This measurement probes variations in the spatial gradient of the line-of-sight total electron content (TEC) to ∼10 −3 TECU km −1 (1 TECU = 10 12 cm −2 ) accuracy over spatial scales of under 10 km to over 100 km. We use data from the VLA Low-frequency Sky Survey (VLSS), a nearly complete 74 MHz survey of the entire sky visible to the VLA telescope in Socorro, New Mexico. These data comprise over 500 hr of observations, all calibrated in a standard way. While ionospheric spatial structure varies greatly from one observation to the next, when analyzed over hundreds of hours, statistical patterns become apparent. We present a detailed characterization of how the median differential refraction depends on source pair separation, elevation, and time of day. We find that elevation effects are large, but geometrically predictable and can be "removed" analytically using a "thinshell" model of the ionosphere. We find significantly greater ionospheric spatial variations during the day than at night. These diurnal variations appear to affect the larger angular scales to a greater degree indicating that they come from disturbances on relatively larger spatial scales (hundreds of kilometers, rather than tens of kilometers).

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Section: Dependence On Elevationmentioning

confidence: 99%

Probing Fine-Scale Ionospheric Structure With the Very Large Array Radio Telescope

Cohen

Röttgering

2009

The Astronomical Journal

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“…Observations, using data transmitted by other satellites, show that the sinusoidal-like TEC difference changes independently for each satellite, indicating environmental independent errors (temperature, humidity, etc. ), Lanyi and Roth (1988) explained this distinction as P-code offsets and multipath effects. High frequency deviations appear at low elevation angle, at the beginning and the end of observation session, when the satellite rises and sets.…”

Section: Sensitivity Of Ionospheric Measurements Using Gps Observationsmentioning

confidence: 99%

Comparison of simultaneous variations of the ionospheric total electron content and geomagnetic field associated with strong earthquakes

Naaman

Alperovich

Wdowinski

et al. 2001

Nat. Hazards Earth Syst. Sci.

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Abstract. In this paper, perturbations of the ionospheric Total Electron Content (TEC) are compared with geomagnetic oscillations. Comparison is made for a few selected periods, some during earthquakes in California and Japan and others at quiet periods in Israel and California. Anomalies in TEC were extracted using Global Positioning System (GPS) observations collected by GIL (GPS in Israel) and the California permanent GPS networks. Geomagnetic data were collected in some regions where geomagnetic observatories and the GPS network overlaps. Sensitivity of the GPS method and basic wave characteristics of the ionospheric TEC perturbations are discussed. We study temporal variations of ionospheric TEC structures with highest reasonable spatial resolution around 50 km. Our results show no detectable TEC disturbances caused by right-lateral strike-slip earthquakes with minor vertical displacement. However, geomagnetic observations obtained at two observatories located in the epicenter zone of a strong dip-slip earthquake (Kyuchu, M = 6.2, 26 March 1997) revealed geomagnetic disturbances occurred 6-7 h before the earthquake.

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“…The morphological features of TEC such as the diurnal, seasonal, latitudinal, and solar activity variations have been investigated by several workers using various techniques over different parts of the globe [Lanyi and Roth, 1988;Goodwin et al, 1995;Abdu et al, 1996;Davies and Hartman, 1997;Mannucci et al, 1998;Afraimovich et al, 2001;Brunini et al, 2003;Jee et al, 2005;Rama Rao et al, 2006;Bagiya Mala et al, 2009;Prasad et al, 2012]. One of the most important electrodynamical features of the equatorial ionosphere is the double-humped latitudinal distribution of ionization centered at the dip equator, which is popularly known as the equatorial ionization anomaly (EIA) [Appleton, 1946].…”

Section: Introductionmentioning

confidence: 99%

On the performance of the IRI‐2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low‐latitude sectors

Venkatesh

Fagundes

Seemala³

et al. 2014

JGR Space Physics

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It is known that the equatorial and low-latitude ionosphere is characterized with typical dynamical phenomena namely, the equatorial ionization anomaly (EIA). Accurate modeling of the characteristic variations of the EIA is more important to arrive at the correct estimation of range delays required for the communication and navigation applications. The total electron content (TEC) data from a chain of Global Positioning System (GPS) receivers at seven identified locations from equator to the anomaly crest and beyond along 315°E geographic longitude in the Brazilian sector are considered. The performances of the latest available IRI-2012 and NeQuick2 models have been investigated during 2010-2013 in the increasing phase of the 24th solar cycle. A comparative study on the morphological variations of the GPS measured and modeled TEC revealed that the performances of the models are improved during low solar activity periods compared to that during the increased solar activity years. The strength and the locations of the EIA crest are nearly well represented by both the models during the low solar activity while the models underestimate the peak TEC at the EIA during the increased solar activity conditions. The deviations between the GPS-measured and model-derived TEC are more during equinoctial and summer months at and around the anomaly crest locations. Significant differences have also been observed in between the TEC values derived from both the models. The causes for the discrepancies in the modeled TEC values are discussed based on the model-derived and ionosonde-measured vertical electron density profiles variations.

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A comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations

Cited by 295 publications

References 5 publications

Probing Fine-Scale Ionospheric Structure With the Very Large Array Radio Telescope

Probing Fine-Scale Ionospheric Structure With the Very Large Array Radio Telescope

Comparison of simultaneous variations of the ionospheric total electron content and geomagnetic field associated with strong earthquakes

On the performance of the IRI‐2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low‐latitude sectors

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