Comparison of two IRI electron-density plasmasphere extensions with GPS-TEC observations

Gulyaeva, T.L.; Gallagher, D. L.

doi:10.1016/j.asr.2007.01.064

Cited by 14 publications

(5 citation statements)

References 15 publications

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“…The EOF TEC models have been developed by extracting the EOF basis modes and then fitting the associated amplitude coefficients. To validate the EOF TEC models, two ionospheric and plasmaspheric empirical models, GCPM (Gallagher et al, 2000) and IRI-PLAS (Gulyaeva & Gallagher, 2007), have been used for comparison. These two empirical models are based on the IRI model (Bilitza & Reinisch, 2008) and include plasmaspheric extensions.…”

Section: Discussionmentioning

confidence: 99%

“…The Global Core Plasma Model (GCPM) is smoothly coupled to the International Reference Ionosphere (IRI) 2007 model at transition altitudes of 400–600 km and provides empirically derived plasma density in the plasmasphere (Gallagher et al, ). The IRI‐PLAS model represents empirical global vertical profiles of electron density, gradually fitted to the IRI model at 1,000 km altitude and extends toward the plasmapause up to 36,000 km (Gulyaeva & Gallagher, ). However, the plasma density profile above the F 2 peak is often reconstructed based on the assumption of O + ‐H + diffusive equilibrium with constant scale heights, which could lead to an artificial exponential‐like shape (e.g., Bilitza et al, ; Stankov et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Empirical Orthogonal Function Analysis and Modeling of the Topside Ionospheric and Plasmaspheric TECs

et al. 2019

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The topside total electron contents (TECs) observed by the MetOp‐A (above 832 km) and TerraSAR‐X (above 520 km) satellites for multiple local times during 2008–2018 have been used to develop global topside ionospheric and plasmaspheric TEC models, based on empirical orthogonal function (EOF) analysis. Gridded TEC maps are first obtained from the original quiet time TECs, and then, they are decomposed into EOF basis modes and associated amplitude coefficients. The EOF analysis well captures the latitudinal, longitudinal, and seasonal variations of the topside ionosphere and plasmasphere, and the associated dependence on solar EUV forcing. The first five EOFs, which can account for more than 98.8% of the total variance, are applied in model construction. The comparison with two empirical models indicates that the EOF TEC models can reproduce the observations well, including TEC magnitudes and longitudinal variations. Moreover, the annual anomaly is obviously seen in the topside TECs. The global averaged TECs are greatest in December and smallest in June. With increasing solar EUV forcing, the global averaged TECs always increase, but the winter hemisphere TECs do not change much and even decrease, especially at night and in the Southern Hemisphere. The overall increasing rate with solar EUV forcing is larger under higher solar activity conditions. The direct plasma diffusion through ionosphere‐plasmasphere coupling may not be able to explain some of the features seen in the topside TECs.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Empirical Orthogonal Function Analysis and Modeling of the Topside Ionospheric and Plasmaspheric TECs

et al. 2019

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“…At the same time, the IRI‐Plas model includes the plasmasphere specifications, but currently, it overestimates the plasmaspheric TEC values derived from spaceborne GPS measurements, as well as TEC results retrieved by the NeQuick 2 model. It was also reported that that the IRI‐Plas overestimates the plasmaspheric TEC simulated by the Global Core Plasma Model‐2000 by an order of magnitude at 6370 km altitude, becoming 2 to 3 orders of magnitude larger at the GPS satellite orbital altitude of 20,200 km [ Gulyaeva and Gallagher , ].…”

Section: Discussionmentioning

confidence: 99%

NeQuick and IRI‐Plas model performance on topside electron content representation: Spaceborne GPS measurements

Cherniak¹,

Zakharenkova

2016

Radio Science

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The correct representation of the topside ionosphere is still an open question for the empirical ionospheric models. We presents new results of the concurrent analysis of the topside electron content values derived from the GPS measurements on board the GOCE and TerraSAR-X satellites with two empirical ionospheric models: NeQuick 2 and IRI-Plas. Two periods of low (2009/2010) and moderate (2012) solar activities were analyzed. It is found that the IRI-Plas model overestimates the electron content in the 250-500 km altitude interval for low solar activity and the topside total electron content (TEC) for the 500-20,000 km altitude range during daytime local time at low and moderate solar activities. The NeQuick 2 model demonstrates very similar to the IRI-Plas results for the 250-500 km region and the opposite behavior for the region above 500 km with underestimated values for all considered seasons and local time. The most important region for the model/model differences was found to be within the altitude range of 500-2000 km. The observed understatement in the NeQuick 2 topside TEC results can be related to the simplified extension of the electron density profile toward the GPS orbit altitude without adjustment of the specific plasmasphere model. However, the plasmasphere model included into the IRI-Plas leads to the noticeable overestimation of the TEC values derived from the spaceborne GPS measurements.

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“…The contribution of the plasmaspheric electron density to TEC cannot be neglected (Gulyaeva and Titheridge, 2006;Gulyaeva and Gallagher 2007;Cueto et al, 2007;Reinisch et al, 2007). However, observations of the electron density to construct a reliable model are limited in the topside ionosphere and plasmasphere compared with the bottomside and the F-layer peak (Bilitza and Williamson, 2000).…”

Section: Introductionmentioning

confidence: 99%

Regional reference total electron content model over Japan based on neural network mapping techniques

Maruyama

2007

Ann. Geophys.

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Abstract.A regional reference model of total electron content (TEC) was constructed using data from the GPS Earth Observation Network (GEONET), which consists of more than 1000 Global Positioning System (GPS) satellite receivers distributed over Japan. The data covered almost one solar activity period from April 1997 to June 2007. First, TECs were determined for 32 grid points, expanding from 27 to 45 • N in latitude and from 127 to 145 • E in longitude at 15-min intervals. Secondly, the time-latitude variation averaged over three days was determined by using the surface harmonic functional expansion. The coefficients of the expansion were then modeled by using a neural network technique with input parameters of the season (day of the year) and solar activity (F10.7 index and sunspot number). Thus, two-dimensional TEC maps (time vs. latitude) can be obtained for any given set of solar activity and day of the year.

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Comparison of two IRI electron-density plasmasphere extensions with GPS-TEC observations

Cited by 14 publications

References 15 publications

Empirical Orthogonal Function Analysis and Modeling of the Topside Ionospheric and Plasmaspheric TECs

Empirical Orthogonal Function Analysis and Modeling of the Topside Ionospheric and Plasmaspheric TECs

NeQuick and IRI‐Plas model performance on topside electron content representation: Spaceborne GPS measurements

Regional reference total electron content model over Japan based on neural network mapping techniques

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