GIM-TEC adaptive ionospheric weather assessment and forecast system

Gulyaeva, T.L.; Arıkan, Feza; Hernández‐Pajares, M.; Stanisławska, I.

doi:10.1016/j.jastp.2013.06.011

Cited by 99 publications

(67 citation statements)

References 31 publications

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“…Hence, GPS TEC can be considered the combined contribution of the ionosphere and the overlying plasmasphere. The international standard plasmasphereionosphere model (SPIM) (Gulyaeva and Bilitza, 2012;Gulyaeva et al, 2013) combines the International Reference Ionosphere (IRI) with the Russian standard model of the ionosphere and plasmasphere (SMI). One of the advantages of this model is that it can provide TEC at altitudes of 80 to 35 000 km for any location on Earth.…”

Section: Discussionmentioning

confidence: 99%

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

Huang

Yuan

2015

Ann. Geophys.

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Abstract. The ionospheric slab thickness is defined as the ratio of the total electron content (TEC) to the ionospheric F2 layer peak electron density (NmF2). In this study, the slab thickness is determined by measuring the ionospheric TEC from dual-frequency Global Positioning System (GPS) data and the NmF2 from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC). A statistical analysis of the diurnal, seasonal and spatial variation in the ionospheric slab thickness is presented along the longitude of 120 • E in China and its adjacent region during the recent solar minimum phase (2007)(2008)(2009). The diurnal ratio, defined as the maximum slab thickness to the minimum slab thickness, and the night-to-day ratio, defined as the slab thickness during daytime to the slab thickness during night-time, are both analysed. The results show that the TEC of the northern crest is greater in winter than in summer, whereas NmF2 is greater in summer than in winter. A pronounced peak of slab thickness occurs during the postmidnight (00:00-04:00 LT) period, when the peak electron density is at the lowest level. A large diurnal ratio exists at the equatorial ionization anomaly, and a large night-to-day ratio occurs near the equatorial latitudes and mid-to high latitudes. It is found that the behaviours of the slab thickness and the F2 peak altitude are well correlated at the latitudes of 30-50 • N and during the period of 10:00-16:00 LT. This current study is useful for improvement of the regional model and accurate calculation of the signal delay of radio waves propagating through the ionosphere.

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Section: Discussionmentioning

confidence: 99%

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

Huang

Yuan

2015

Ann. Geophys.

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“…W index as a measure of the ionosphere-plasmasphere state is generated at each grid point of geomagnetic coordinates map with relevant thresholds for logarithmic deviation of TEC from 7 days running median of the type: DTEC = log(TECobs/TECmed) (Gulyaeva et al, 2013). The positive sign of DTEC refers to TEC enhancement, the negative sign to depletion.…”

Section: Data Processingmentioning

confidence: 99%

“…The 7 days backwards median is particularly suitable for the present study by selecting the events for which the pre-storm 7 days median is not affected by the magnetically disturbed conditions. With a system of adopted thresholds for DTEC (Gulyaeva et al, 2013) the magnitude of W index varies from W = 0 or ±1 for the quiet state to W = ±2 for the moderate disturbance, W = ±3 for the moderate ionospheric storm, and W = ±4 for the intense ionospheric storm. In the present study the map cells under positive storm conditions (W = 3 and 4) and negative storm conditions (W = −3 and −4) are identified for each hourly UT map, each day and month during 1999-2012 from W index maps in magnetic coordinates.…”

Section: Data Processingmentioning

confidence: 99%

“…Global Ionospheric Maps of Total Electron Content (GIM-TEC) are cost-effective and user friendly means in observation of global distribution of TEC. A recently developed ionospheric W index proved itself a versatile tool in distinguishing the ionospheric and plasmaspheric variability state, and thus identifying the stages and intensity of ionosphere storms Stanislawska, 2008, 2010;Gulyaeva et al, 2011Gulyaeva et al, , 2013. The computation of W index is based on GIM-TEC and its value can range from quiet state (−1 ≤ W ≤ + 1) to moderate storm (W = ±3) and intense storm (W = ±4).…”

Section: Introductionmentioning

confidence: 99%

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Probability of occurrence of planetary ionosphere storms associated with the magnetosphere disturbance storm time events

2014

Self Cite

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Abstract. The ionospheric W index allows to distinguish state of the ionosphere and plasmasphere from quiet conditions (W = 0 or ±1) to intense storm (W = ±4) ranging the plasma density enhancements (positive phase) or plasma density depletions (negative phase) regarding the quiet ionosphere. The global W index maps are produced for a period 1999-2014 from Global Ionospheric Maps of Total Electron Content, GIM-TEC, designed by Jet Propulson Laboratory, converted from geographic frame (−87.5:2.5:87.5 • in latitude, −180:5:180 • in longitude) to geomagnetic frame (−85:5:85 • in magnetic latitude, −180:5:180 • in magnetic longitude). The probability of occurrence of planetary ionosphere storm during the magnetic disturbance storm time, Dst, event is evaluated with the superposed epoch analysis for 77 intense storms (Dst ≤ −100 nT) and 230 moderate storms (−100 < Dst ≤ −50 nT) with start time, t 0 , defined at Dst storm main phase onset. It is found that the intensity of negative storm, iW − , exceeds the intensity of positive storm, iW + , by 1.5-2 times. An empirical formula of iW + and iW − in terms of peak Dst is deduced exhibiting an opposite trends of relation of intensity of ionosphere-plasmasphere storm with regard to intensity of Dst storm.

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“…Even the rapid product is delayed by two days, and the mean accuracy is 2-8 TECu worldwide [16,17]. Alternatively, some IGS analysis centers can provide a two-day ahead prediction product [18]. However, this product cannot satisfy the requirement of high-accuracy positioning if the area is lacking an IGS station [19].…”

Section: Introductionmentioning

confidence: 99%

Applicability Analysis of VTEC Derived from the Sophisticated Klobuchar Model in China

Huang

Liu

et al. 2017

IJGI

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Abstract:Although the Klobuchar model is widely used in single-frequency GPS receivers, it cannot effectively correct the ionospheric delay. The Klobuchar model sets the night ionospheric delay as a constant, i.e., it cannot reflect temporal changes at night. The observation data of seventeen International Global Navigation Satellite System Service (IGS) stations within and around China from 2011 provided by the IGS center are used in this study to calculate the Total Electron Content (TEC) values using the Klobuchar model and the dual-frequency model. The Holt-Winters exponential smoothing model is used to forecast the error of the 7th day between the Klobuchar model and the dual-frequency model by using the error of the former six days. The forecast results are used to develop the sophisticated Klobuchar model when no epochs are missing, considering that certain reasons may result in some of the observation data being missing and weaken the relationship between each epoch in practical applications. We study the applicability of the sophisticated Klobuchar model when observation data are missing. This study deletes observation data of some epochs randomly and then calculates TEC values using the Klobuchar model. A cubic spline curve is used to restore the missing TEC values calculated in the Klobuchar mode. Finally, we develop the sophisticated Klobuchar model when N epochs are missing in China. The sophisticated Klobuchar model is compared with the dual-frequency model. The experimental results reveal the following: (1) the sophisticated Klobuchar model can correct the ionospheric delay more significantly than the Klobuchar model; (2) the sophisticated Klobuchar model can reflect the ionosphere temporal evolution, particularly at night, with the correct results increasing with increasing latitude; and (3) the sophisticated Klobuchar model can achieve remarkable correction results when N epochs are missing, with the correct results being nearly as good as that of the dual-frequency model when no epochs are missing.

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GIM-TEC adaptive ionospheric weather assessment and forecast system

Cited by 99 publications

References 31 publications

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

Probability of occurrence of planetary ionosphere storms associated with the magnetosphere disturbance storm time events

Applicability Analysis of VTEC Derived from the Sophisticated Klobuchar Model in China

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