The IGS VTEC maps: a reliable source of ionospheric information since 1998

Hernández‐Pajares, Manuel; Zornoza, José Miguel Juan; Sanz, J.; Orús, R.; García-Rigo, Alberto; Feltens, J.; Komjáthy, A.; Schaer, Stefan; Krankowski, Andrzej

doi:10.1007/s00190-008-0266-1

Cited by 882 publications

(617 citation statements)

References 16 publications

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“…This may be related to different GIM modeling algorithms used for CODE and JPL, for example, the methods for CODE and JPL to remove the differential code biases are different. From statistics of the difference between T/J vTEC and GNSS vTEC for almost five years (see Table 1 of Hernández-Pajares et al [43]), we can infer that the difference between CODE GIM and JPL GIM is insufficient, no more than 2 TECu (JPL minus CODE). Moreover, the GIM-based interpolation vTEC from CODE and JPL is consistent with that of the GPS dual-frequency measurements, and the accuracy of GIM-derived vTEC in our study is at most within 2 TECu, because the T/J and GNSS overlapping areas have already been selected to minimize interpolation errors on GIMs and the determination of the GIM-derived vTEC should not be so affected by the interpolation scheme.…”

Section: Discussionmentioning

confidence: 95%

Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

et al. 2018

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Abstract:The plasmasphere, which is located above the ionosphere, is a significant component of Earth's atmosphere, and the plasmasphere electron content (PEC) distribution is determined by different physical mechanisms to those of the ionosphere electron content (IEC). However, the observation for the PEC is very limited. In this study, we introduced a methodology (called zero assumption method, which is based on the assumption that PEC can reach zero) to extract the PEC over TOPEX/JASON (T/J) and global navigation satellite system (GNSS) overlapping areas. Results show that the daily systematic bias (T/J vertical TEC > GNSS-derived vertical TEC) for both low (2009) and high (2011) solar activity condition is consistent, and the systematic bias for JASON2 and JASON1 is different. We suggest that systematic biases predominantly arise from the sea state bias (SSB), especially the tracker bias. After removing the systematic bias, we extracted reliable PEC inferred from differences between GNSS-derived vertical TEC and T/J vertical TEC data. Finally, the characteristics of the plasmaspheric component distribution for different local times, latitudes, and seasons were investigated.

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Section: Discussionmentioning

confidence: 95%

Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

et al. 2018

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“…The narrow FWHM of the functions allows the peaks associated with the pulsar (2.373±0.011 and 2.136±0.061 rad m −2 , respectively) and instrumental response (∼0 rad m −2 ) to be individually resolved, despite the very low absolute rotation measure (RM). These RMs were corrected for ionospheric Faraday rotation (0.899 ± 0.042 and 0.665 ± 0.059 rad m −2 , respectively) using the ionFR code which employs International GNSS Service vertical total electron content (VTEC) maps (Hernández-Pajares et al 2009) and data from the International Geomagnetic Reference Field (Finlay et al 2010) (see Sotomayor-Beltran et al 2013). The resulting RM of the ISM toward B0950+08 was determined to be 1.47 ± 0.04 and 1.47 ± 0.08 rad m −2 , from LBA and HBA observations respectively.…”

Section: Magnetic Fields In the Universementioning

confidence: 99%

LOFAR: The LOw-Frequency ARray

Haarlem

Wise

Gunst

et al. 2013

A&A

2,096

783

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LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10-240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of Exloo in the northeast of the Netherlands, a total of 40 LOFAR stations are nearing completion. A further five stations have been deployed throughout Germany, and one station has been built in each of France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unparalleled sensitivity and angular resolution in the low-frequency radio regime. The LOFAR facilities are jointly operated by the International LOFAR Telescope (ILT) foundation, as an observatory open to the global astronomical community. LOFAR is one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. LOFAR's new capabilities, techniques and modus operandi make it an important pathfinder for the Square Kilometre Array (SKA). We give an overview of the LOFAR instrument, its major hardware and software components, and the core science objectives that have driven its design. In addition, we present a selection of new results from the commissioning phase of this new radio observatory.

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“…The latter approach is capable of improving the retrieval algorithm with relatively low implementation effort under support of global ionosphere maps (GIMs) as shown, for instance, by Hernán-dez-Pajares et al (2000), Garcia-Fernandez et al (2003), and Aragon-Angel (2010). Therefore, the UPC approach has been applied in this work involving GIMs (Hernández-Pajares et al 2009) provided by the International GNSS Service (IGS; Dow et al 2009) in the Ionosphere Map Exchange (IONEX) format. Few potential drawbacks, however, remain.…”

Section: Introductionmentioning

confidence: 99%

Long-term comparison of the ionospheric F2 layer electron density peak derived from ionosonde data and Formosat-3/COSMIC occultations

Limberger¹,

Hernández‐Pajares

Aragón‐Àngel

et al. 2015

J. Space Weather Space Clim.

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Electron density profiles (EDPs) derived from GNSS radio occultation (RO) measurements provide valuable information on the vertical electron density structure of the ionosphere and, among others, allow the extraction of key parameters such as the maximum electron density NmF2 and the corresponding peak height hmF2 of the F2 layer. An efficient electron density retrieval method, developed at the UPC (Barcelona, Spain), has been applied in this work to assess the accuracy of NmF2and hmF2 as determined from Formosat-3/COSMIC (F-3/C) radio occultation measurements for a period of more than half a solar cycle be- ) and local times (LT) accounting for different ionospheric conditions at night (02:00 LT ± 2 h), dawn (08:00 LT ± 2 h), and day (14:00 LT ± 2 h). The mean differences of F2 layer electron density peaks observed by F-3/C and ionosondes are found to be insignificant. Relative variations of the peak differences are determined in the range of 22%-30% for NmF2 and 10%-15% for hmF2. The consistency of observations is generally high for the equatorial and mid-latitude sectors at daytime and dawn whereas degradations have been detected in the polar regions and during night. It is shown, that the global averages of NmF2 and hmF2 derived from F-3/C occultations appear as excellent indicators for the solar activity.

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The IGS VTEC maps: a reliable source of ionospheric information since 1998

Cited by 882 publications

References 16 publications

Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

LOFAR: The LOw-Frequency ARray

Long-term comparison of the ionospheric F2 layer electron density peak derived from ionosonde data and Formosat-3/COSMIC occultations

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