GPS-based TEC observations in comparison with IRI95 and the European TEC model NTCM2

Jakowski, N.; Sardón, E.; Schlüter, Stefan

doi:10.1016/s0273-1177(98)00101-x

Cited by 40 publications

(32 citation statements)

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“…8d) This lag (of about 2 days) of the 27-day GEC variations, as compared with the corresponding changes in the EUV and radio 10.7-cm solar emissions (Figs. 7 and 8), is in agreement with the data presented by Jakowski et al (1991Jakowski et al ( , 1998Jakowski et al ( , 2002. Figure 7d shows the envelopes EdG(t), EdF(t) and EdU(t) of the maximal values of the 27-day variations of the dG(t), dF(t) and dU(t) presented in Figs.…”

Section: -Day Variations Of Gec -Comparison With Variations Of Solasupporting

confidence: 89%

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Global electron content: a new conception to track solar activity

et al. 2008

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Abstract. We developed a method and programs for estimation of the global electron content (GEC) from GPS measurements, using the ionosphere models IRI-2001 and NeQuick. During the 23rd cycle of solar activity, the value of GEC varied from 0.8 to 3.2×10 32 electrons, following changes in the solar extreme ultra violet (EUV) radiation and solar radio emission at 10.7-cm wavelength. We found a strong resemblance of these variations, with discernible 11-year and 27-day periodicities. A saturation effect of GEC is found when F10.7 increases. We found that GEC is characterized by strong seasonal (semiannual) variations with maximum relative amplitude at about 10% during the rising and falling parts of the solar activity and up to 30% during the period of maximum. It was found that the relative difference between model and experimental GEC series increase as the smoothing time window decreases. We found that GEC-IRI seasonal variations are out-of-phase with experimental GEC values. The lag between model and experimental maximum of GEC values can reach several tens of days. The variations of GEC lag, on average, 2 days after those of F10.7 and UV. GEC completely reflects the dynamics of the active regions on the solar surface. The amplitude of the 27-day GEC variations decreases from 8% at the rising and falling solar activity to 2% at the maximum and at the minimum. We also found that the lifetime of contrast long-living active formations on the Sun's surface in EUV range for more than 1 month exceeds the one in radio range (10.7 cm).

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Section: -Day Variations Of Gec -Comparison With Variations Of Solasupporting

confidence: 89%

“…Many works have been devoted to researching of this factor (Akasofu and Chapmen, 1972;Ivanov-Kholodny and Nikolsky, 1969;Vitinsky et al, 1986;Jakowski et al, 1991Jakowski et al, , 1998Jakowski et al, , 2002. However, quasi 27-day modulation of local ionosphere parameters can be masked by many other factors.…”

Section: Introductionmentioning

confidence: 99%

Global electron content: a new conception to track solar activity

et al. 2008

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“…Consequently, a family of regional empirical TEC models, the Neustrelitz TEC Model (NTCM), has been developed in DLR which provides climatological information on TEC behavior: the NTCM-EU for Europe, and the NTCM-NP and NTCM-SP for North and South Pole areas, respectively (e.g., Jakowski 1996; Jakowski et al 1998;Jakowski et al 2011b). To ensure a high quality of the TEC maps also in case of only a few measurements or at greater distances from the measuring points, the measured data are combined with the empirical TEC model which has been developed specifically for the region in view.…”

Section: Tec Modeling Activities At German Aerospace Center (Dlr) In mentioning

confidence: 99%

Progress in space weather modeling in an operational environment

Tsagouri

Belehaki

Bergeot

et al. 2013

J. Space Weather Space Clim.

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This paper aims at providing an overview of latest advances in space weather modeling in an operational environment in Europe, including both the introduction of new models and improvements to existing codes and algorithms that address the broad range of space weather's prediction requirements from the Sun to the Earth. For each case, we consider the model's input data, the output parameters, products or services, its operational status, and whether it is supported by validation results, in order to build a solid basis for future developments. This work is the output of the Sub Group 1.3 ''Improvement of operational models'' of the European Cooperation in Science and Technology (COST) Action ES0803 ''Developing Space Weather Products and services in Europe'' and therefore this review focuses on the progress achieved by European research teams involved in the action.

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“…The estimation of the ionospheric effect is significant for all kinds of earth observation applications and space weather studies. There are many currently available ionosphere models in order to define the TEC under various space weather conditions [12,13,14,15,16,17,18,19]. The dispersive and heterogeneous nature of the ionosphere provides the opportunity to determine the TEC distribution by using dual frequency GPS observables.…”

Section: Introductionmentioning

confidence: 99%

A new approach to outlying data in estimation of vertical total electron content

Erenoǧlu

2015

Teh. vjesn.

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Original scientific paper For all scientific studies, for processing analytical data the subject of outliers is of critical importance. The accuracy of Total Electron Content (TEC) models obtained from ground based Global Positioning Systems (GPS) data is strongly affected by some factors such as satellite geometry, cut-off angle, ionospheric shell height, quantity of GPS data etc. Probable outliers within the observables have a significant effect on the quality of the estimated TEC modelling. These should be removed from the TEC time series in order to get more reliable results for further process. Although some analytical methods have been developed for the code-outliers, phase-slips and ionosphere disturbances, significant reduction in the number of measurement could adversely affect the quality of the generated TEC values using geometry-free combinations of those. In this study, we proposed a novel approach for outlier detection to be used at geometry-free combinations in estimation of vertical TEC without reducing the number of code observables. Here the GPS data obtained from 22 permanent stations are used to estimate the VTEC on May 14-15, 2005. The research results from the detailed processing clearly show the efficiency of the method. Our research shows that the proposed approach appears to be a fast, effective and objective method to detect outlying effects which cause improper modelling. Moreover the resulting VTEC maps from the new approach differ reliably with respect to the data including outlying observables. Consequently, the proposed method could provide an alternative to outlier rejection in estimation of VTEC, in which outlying observations are retained in geometry-free combinations. Keywords: discordant data; GPS; median; outlier; total electron content Novi pristup vanjskim (outlying) podacima u procjeni vertikalnog ukupnog sadržaja elektronaIzvorni znanstveni članak U svim vrstama znanstvenih studija, za obradu analitičkih podataka pitanje outliera je od bitne važnosti. Na točnost Total Electron Content (TEC) modela koja se postiže na temelju podataka Sustava za Globalno Pozicioniranje (GPS) sa zemlje uvelike djeluju čimbenici kao što su geometrija satelita, kut prekida, visina ionosferske ljuske, količina GPS podataka i sl. Vjerojatni outlieri među promatranima imaju značajan učinak na kvalitetu procijenjenog TEC modeliranja. Njih je potrebno ukloniti iz TEC vremenskih serija kako bi se dobili pouzdaniji rezultati za daljnji postupak. Iako su neke analitičke metode razvijene za code-outliers, phase-slips i poremećaje u ionosferi, značajno smanjenje broja mjerenja negativno bi moglo utjecati na kvalitetu nastalih TEC vrijednosti primjenom njihovih kombinacija bez geometrije. U ovom istraživanju, predložili smo novi pristup za otkrivanje outliera koji će se koristiti u kombinacijama bez geometrije u procjeni vertikalnog TEC-a bez smanjenja broja promatrača koda. Ovdje se GPS podaci dobiveni iz 22 stalnih postaja koriste za procjenu VTEC-a na dan 14-15 svibnja 2005. Rezultati istraživanja dob...

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GPS-based TEC observations in comparison with IRI95 and the European TEC model NTCM2

Cited by 40 publications

References 5 publications

Global electron content: a new conception to track solar activity

Global electron content: a new conception to track solar activity

Progress in space weather modeling in an operational environment

A new approach to outlying data in estimation of vertical total electron content

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