Topside Ionosphere and Plasmasphere Modelling Using GNSS Radio Occultation and POD Data

Prol, Fabricio dos Santos; Hoque, Mohammed Mainul

doi:10.3390/rs13081559

Cited by 8 publications

(7 citation statements)

References 32 publications

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“…For instance, Cherniak and Zakharenkova 33 points out that IRI-Plas 34 and NeQuick 11 needs to be essentially improved above the F2 layer peak (hmF2) for better characterization of the topside Total Electron Content (TEC). Additionally, Kashcheyev and Nava 35 and Prol et al 36 show that NeQuick is systematically predicting lower TEC values in comparison to satellite-based TEC measurements.…”

Section: Introductionmentioning

confidence: 93%

Combined model of topside ionosphere and plasmasphere derived from radio-occultation and Van Allen Probes data

Prol

Smirnov

Hoque

et al. 2022

Sci Rep

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In the last years, electron density profile functions characterized by a linear dependence on the scale height showed good results when approximating the topside ionosphere. The performance above 800 km, however, is not yet well investigated. This study investigates the capability of the semi-Epstein functions to represent electron density profiles from the peak height up to 20,000 km. Electron density observations recorded by the Van Allen Probes were used to resolve the scale height dependence in the plasmasphere. It was found that the linear dependence of the scale height in the topside ionosphere cannot be directly used to extrapolate profiles above 800 km. We find that the dependence of scale heights on altitude is quadratic in the plasmasphere. A statistical model of the scale heights is therefore proposed. After combining the topside ionosphere and plasmasphere by a unified model, we have obtained good estimations not only in the profile shapes, but also in the Total Electron Content magnitude and distributions when compared to actual measurements from 2013, 2014, 2016 and 2017. Our investigation shows that Van Allen Probes can be merged to radio-occultation data to properly represent the upper ionosphere and plasmasphere by means of a semi-Epstein function.

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Section: Introductionmentioning

confidence: 93%

Combined model of topside ionosphere and plasmasphere derived from radio-occultation and Van Allen Probes data

Prol

Smirnov

Hoque

et al. 2022

Sci Rep

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“…It comprises six identical micro-satellites running on the circular low-Earth orbit with an orbital period of 100 min and an orbital inclination of 72°. Each satellite carries a GPS RO receiver and a POD receiver, which can be used not only to obtain continuous TEC observations between COSMIC and GPS satellite pair during an occultation event and retrieve the ionospheric electron densities via Abel inversion [2,15,35] but also to receive signals from GPS satellites running on its line of sight directly and retrieve the topside TEC observations [7,9,22,31]. Various observation data from COSMIC/FORMAT-3 have provided great convenience for the study of the ionosphere and plasmasphere, and they are now available for free from the COSMIC Data Analysis and Archive Center (CDAAC).…”

Section: Podtec Datasetmentioning

confidence: 99%

“…The ionosphere, including the F-layer, contributes the majority of the total electron content (TEC) [1][2][3][4][5][6]. In the plasmasphere, however, the electron density is generally several orders of magnitude less than that in the ionosphere, but it can extend from the topside of the F-layer to an altitude of 3∼5 times the Earth's radius [7][8][9]. In ground-based GNSS applications, the length of the GNSS signals' propagation path in the plasmasphere usually accounts for more than 95% of the satellite-receiver distance, and in this case, the integral plasmaspheric electron content (PEC) along the ray path is still considerable, although with the quite low electron densities.…”

Section: Introductionmentioning

confidence: 99%

“…However, a lot of assumptions are usually needed for the 3-D elec-tron density models in dealing with the EDP of the plasmasphere because of the limited achievable data [27][28][29][30]. For example, the EDP of the plasmasphere is usually considered to be an extension of the ionospheric F-layer, and an artificially specified exponential function is used to extend the EDP to an altitude of thousands of kilometers [7,30]. On this condition, the EDP of the plasmasphere strongly relies on the shape of the EDP in the ionosphere, and some artificial mistakes may be introduced, such as the two-peak structure of the Equatorial Ionization Anomaly (EIA) that rarely occurs in plasmasphere [2,9].…”

Section: Introductionmentioning

confidence: 99%

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An EOF-Based Global Plasmaspheric Electron Content Model and Its Potential Role in Vertical-Slant TEC Conversion

Long,

Gao,

Dong

et al. 2024

Remote Sensing

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Topside total electron content (TEC) data measured by COSMIC/FORMAT-3 during 2008 and 2016 were used to analyze and model the global plasmaspheric electron content (PEC) above 800 km with the help of the empirical orthogonal function (EOF) analysis method, and the potential role of the proposed PEC model in helping Global Navigation Satellite System (GNSS) users derive accurate slant TEC (STEC) from existing high-precision vertical TEC (VTEC) products was validated. A uniform gridded PEC dataset was first obtained using the spherical harmonic regression method, and then, it was decomposed into EOF basis modes. The first four major EOF modes contributed more than 99% of the total variance. They captured the pronounced latitudinal gradient, longitudinal differences, hemispherical differences, diurnal and seasonal variations, and the solar activity dependency of global PEC. A second-layer EOF decomposition was conducted for the spatial pattern and amplitude coefficients of the first-layer EOF modes, and an empirical PEC model was constructed by fitting the second-layer basis functions related to latitude, longitude, local time, season, and solar flux. The PEC model was designed to be driven by whether solar proxy or parameters derived from the Klobuchar model meet the real-time requirements. The validation of the results demonstrated that the proposed PEC model could accurately simulate the major spatiotemporal patterns of global PEC, with a root-mean-square (RMS) error of 1.53 and 2.24 TECU, improvements of 40.70% and 51.74% compared with NeQuick2 model in 2009 and 2014, respectively. Finally, the proposed PEC model was applied to conduct a vertical-slant TEC conversion experiment with high-precision Global Ionospheric Maps (GIMs) and dual-frequency carrier phase observables of more than 400 globally distributed GNSS sites. The results of the differential STEC (dSTEC) analysis demonstrated the effectiveness of the proposed PEC model in aiding precise vertical-slant TEC conversion. It improved by 18.52% in dSTEC RMS on a global scale and performed better in 90.20% of the testing days compared with the commonly used single-layer mapping function.

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“…Ionosonde stations and incoherent scatter radars, for instance, are commonly used as a reference to the validation [12][13][14][15][16][17][18][19][20][21][22] since they provide accurate observations of the electron density. In-situ measurements provided by external satellite missions are also extensively used to assess the RO measurements [23][24][25][26][27][28][29][30]. Another typical evaluation metric is to compare the RO observations against climatological models of the ionosphere [31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Study of Ionospheric Bending Angle and Scintillation Profiles Derived by GNSS Radio-Occultation with MetOp-A Satellite

et al. 2023

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In this work, a dedicated campaign by MetOp-A satellite is conducted to monitor the ionosphere based on radio-occultation (RO) measurements provided by the onboard GNSS (Global Navigation Satellite System) Receiver for Atmospheric Sounding (GRAS). The main goal is to analyze the capabilities of the collected data to represent the bending angle and scintillation profiles of the ionosphere. We compare the MetOp-A products with those generated by other RO missions and explore the spatial/temporal distributions sensed by the MetOp-A campaign. Validation of dual frequency bending angles at the RO tangent points, S4 index, and Rate of the Total electron content Index (ROTI) is performed against independent products from Fengyun-3D and FORMOSAT-7/COSMIC-2 satellites. Our main findings constitute the following: (1) bending angle profiles from MetOp-A agree well with Fengyun-3D measurements; (2) bending angle distributions show a typical S-shape variation along the altitudes; (3) signatures of the sporadic E-layer and equatorial ionization anomaly crests are observed by the bending angles; (4) sharp transitions are observed in the bending angle profiles above ~200 km due to the transition of the daytime/nighttime in addition to the transition of the bottom-side/top-side; and (5) sporadic E-layer signatures are observed in the S4 index distributions by MetOp-A and FORMOSAT-7/COSMIC-2, with expected differences in magnitudes between the GPS (Global Positioning System) L1 and L2 frequencies.

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Topside Ionosphere and Plasmasphere Modelling Using GNSS Radio Occultation and POD Data

Cited by 8 publications

References 32 publications

Combined model of topside ionosphere and plasmasphere derived from radio-occultation and Van Allen Probes data

Combined model of topside ionosphere and plasmasphere derived from radio-occultation and Van Allen Probes data

An EOF-Based Global Plasmaspheric Electron Content Model and Its Potential Role in Vertical-Slant TEC Conversion

Study of Ionospheric Bending Angle and Scintillation Profiles Derived by GNSS Radio-Occultation with MetOp-A Satellite

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