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1

Accuracy assessment of precise point positioning with multi-constellation GNSS data under strong solar burst efects

Savchuk Savchuk, Ćwiklak Janusz, Kerker Vladyslav

Aviation and Security Issues

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2023

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No. 1

239--254

EN

Solar variations modify a layer of the Earth’s upper atmosphere known as the ionosphere. This is of particular concern for the aviation sector because of the way its communications and navigation systems can be affected. At the same time, one of the most complex atmospheric effects is the response of ionospheric regions to geomagnetic storms. The ionospheric response during the same storm can vary in time in different locations, which can introduce significant errors/displacement (meters) in single-frequency relative GNSS positioning (DGNSS technology). The residual effect can be somewhat mitigated by using dual- or multi-frequency GNSS, but dual frequency is not a guarantee against degradation of relative observations results, especially during significant geomagnetic storms. In this regard, PPP absolute positioning technology can be effective. However, another atmospheric effect - ionospheric scintillation can have a significant impact on the accuracy of both GNSS positioning approaches. The main goal of this study was to analyze the effect of second-order ionospheric delay during geomagnetic storms and ionospheric scintillations on GNSS positioning using the PPP method. GNSS data corrected and uncorrected for higher-order ionospheric delay, respectively, were processed by the static PPP-AR method using the PRIDE-PPPAR ver.2.2.6 software for the selected periods of geomagnetic storms. From the analysis of the influence of second-order ionospheric errors, it follows that their values can reach almost 4 cm for first-frequency signals under different states of ionospheric disturbances for the GPS constellation and almost an order of magnitude less for the GNSS quadroconstellation. The appearance of stronger geomagnetic storms increases the second-order ionospheric errors by several millimeters.

PL

Wahania aktywności Słońca modyfikują górną warstwę atmosfery Ziemi, zwaną jonosferą. Jest to szczególnie niepokojące dla sektora lotnictwa ze względu na wpływ, jaki może to mieć na jego systemy łączności i nawigacji. Jednocześnie jednym z najbardziej złożonych efektów atmosferycznych jest reakcja obszarów jonosfery na burze geomagnetyczne. Reakcja jonosfery podczas tej samej burzy może zmieniać się w czasie w różnych lokalizacjach, co może powodować znaczne błędy/ przemieszczenia (rzędu kilku metrów) we względnym pozycjonowaniu GNSS przy jednej częstotliwości (technologia DGNSS). Efekt resztkowy można w pewnym stopniu złagodzić, stosując dwu- lub wieloczęstotliwościowy GNSS, jednak podwójna częstotliwość nie gwarantuje zapobiegania degradacji wyników względnych obserwacji, szczególnie podczas silnych burz geomagnetycznych. Pod tym względem skuteczna może być technologia pozycjonowania absolutnego PPP. Jednak inny efekt atmosferyczny - scyntylacja jonosferyczna może mieć znaczący wpływ na dokładność obu podejść do pozycjonowania GNSS. Głównym celem pracy była analiza wpływu opóźnienia jonosferycznego drugiego rzędu podczas burz geomagnetycznych i scyntylacji jonosferycznych na pozycjonowanie GNSS metodą PPP. Dane GNSS skorygowane i nieskorygowane pod kątem opóźnienia jonosferycznego wyższego rzędu przetworzono statyczną metodą PPP-AR z wykorzystaniem oprogramowania PRIDE-PPPAR wersja 2.2.6 dla wybranych okresów burz geomagnetycznych. Z analizy wpływu błędów jonosferycznych drugiego rzędu wynika, że ich wartości mogą sięgać prawie 4 cm dla sygnałów pierwszej częstotliwości w różnych stanach zaburzeń jonosferycznych dla konstelacji GPS i prawie o rząd wielkości mniej dla kwadrokonstelacji GNSS. Pojawienie się silniejszych burz geomagnetycznych zwiększa błędy jonosferyczne drugiego rzędu o kilka milimetrów.

2

Performance analysis of IRI 2016 model TEC predictions over Northern and Southern Hemispheric IGS stations during descending phase of solar cycle 24

Nibigira Jean de Dieu, Sivavaraprasad G., Ratnam D. Venkata

Acta Geophysica

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2021

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Vol. 69, no. 4

1509--1527

EN

Global Positioning System (GPS) is an efective tool for monitoring the Earth’s ionosphere. This paper concerns with temporal and spatial variations of ionospheric total electron content (TEC) at RAMO, Israel (geographic coordinates: 30.597o N, 34.76o E; geomagnetic coordinates: 27.17o N, 112.40o E), and ZAMB, Zambia (geographic coordinates: 15.42o S, 28.31o E; geomagnetic coordinates: 16.98o S, 98.67o E) for the descending phase of solar cycle-24. The VTEC estimated from GPS measurements and VTEC values modeled from the IRI-2016 model are obtained over both the GPS stations, i.e., RAMO station, in Northern Hemisphere (NH) and ZAMB station in Southern Hemisphere (SH). The diurnal, seasonal, annual, and solar cycle variations in TEC are investigated during 2016–2018. Also, a comparative study is performed between VTEC derived from GPS observations and International Reference Ionosphere-2016 (IRI-2016) model using the statistical analysis. It has been observed that the observed and modeled maximum VTEC decreases with the declining phase of solar cycle-24 over both the stations. The semiannual patterns are noticed in VTEC values of both the IRI-2016 model and GPS observations for all the years, i.e., 2016–2018. At RAMO station, seasonal analysis depicted a year-wise decrease in maximum TEC as follows March Equinox (Mar-Equ), September Equinox (Sep-Equ), December Solstice (Dec-Sol), and June Solstice (Jun Sol). It is observed from the monthly average estimations of the IRI-2016 model that it has relatively more overestimations of VTEC values over RAMO station in NH than over ZAMB in SH during 2016–2018. However, the IRI-2016 model has underestimated the GPS-VTEC values from June–September 2018 over NH, RAMO station. The root-mean-square error (RMSE) values of the IRI-2016 model delineate that the model has more RMSE during March Equinox than September Equinox, whereas these RMSEs are recorded high over NH (RAMO) than SH (ZAMB). At RAMO, the IRI-2016 model has shown high RMSE values during the June solstice compared to the December solstice. On the other hand, at ZAMB, the highest RMSE values are observed during the December solstice than June solstice. Ionolab-TEC and GIM-TEC also considered over both the stations for the analysis. The IRI-2016 model predictions are in good agreement with GPS-VTEC values over SH (ZAMB) compared to NH (RAMO).

3

Ionospheric anomalies detection using autoregressive integrated moving average (ARIMA) model as an earthquake precursor

Saqib Mohd, Şentürk Erman, Sahu Sanjeev Anand, Adil Muhammad Arqim

Acta Geophysica

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2021

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Vol. 69, no. 4

1493--1507

EN

The ARIMA method, time series analysis technique, was proposed to perform short-term ionospheric Total Electron Content (TEC) forecast and to detect TEC anomalies. The success of the method was tested in two major earthquakes that occurred in India (M 7.7 Bhuj EQ, on Jan 26, 2001) and Turkey (M 7.1 Van EQ, on Oct 23, 2011). For ARIMA analysis, we have taken 18 and 29 days of TEC data with a 2-h temporal resolution and train the model with an accuracy of 5.1 and 2.7–2.9 TECU for India and Turkey EQs, respectively. After training the model and optimizing hyper model parameters, we applied on 8 and 9 days’ time-window to observe anomalies. In Bhuj EQ, the negative anomalies are recorded on Jan 19 and 22, 2001. Similarly, positive anomalies are recorded on Jan 23, 24, and 25, 2001. In Van EQ, we recorded a strong positive anomaly on Oct 21, 2011, and in the consecutive days before the earthquake, some weak negative anomalies have also observed. The results showed that ARIMA has an adequate short-term performance of the ionospheric TEC prediction and anomaly detection of the TEC time series.

4

Deep learning for ionospheric TEC forecasting at mid latitude stations in Turkey

Ulukavak Mustafa

Acta Geophysica

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2021

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Vol. 69, no. 2

589--606

EN

Earth’s ionosphere is an important medium for navigation, communication, and radio wave transmission. The inadequate advances in technology do not allow enough realization of ionosphere monitoring systems globally, and most research is still limited to local research in certain parts of the world. However, new methods developed in the feld of forecasting and calculation contribute to the solution of such problems. One of the methods developed is artifcial neural networks-based deep learning method (DLM), which has become widespread in many areas recently and aimed to forecast ionospheric GPS-TEC variations with DLM. In this study, hourly resolution GPS-TEC values were obtained from fve permanent GNSS stations in Turkey. DLM model is created by using the TEC variations and 9 diferent SWC index values between the years 2016 and 2018. The forecasting process (daily, three-daily, weekly, monthly, quarterly, and semi-annual) was carried out for the prediction of the TEC variations that occurred in the frst half-year of 2019. The fndings show that the proposed deep learning-based long short-term memory architecture reveals changes in ionospheric TEC estimation under 1–5 TECU. The calculated correlation coefcient and R2 values between the forecasted GPS-TEC values and the test values are higher than 0.94.

5

Broadcast ionospheric delay correction algorithm using reduced order adjusted spherical harmonics function for single frequency GNSS receivers

Abhigna M. S. R., Sridhar M., Harsha P. Babu Sree, Krishna K. Siva, Ratnam D. Venkata

Acta Geophysica

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2021

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Vol. 69, no. 1

335--351

EN

Single-frequency Global Navigation Satellite System (GNSS) users require an efcient ionospheric delay correction model for improving their positional accuracy. GPS satellite range signals undergo time delay through the inhomogeneous and dynamic state of the ionosphere. The ionospheric delay is inverse proportional to the signal frequency square due to the dispersive nature of the ionospheric medium. There is a need for aid regional ionospheric broadcast correction model that is necessary for low-latitude ionospheric conditions. In this paper, a reduced order adjusted spherical harmonics function (ROASHF) ionospheric broadcast correction model with order and degree 2 is proposed for the Indian region. A dense GPS receiver network of 14 GPS receivers over the Indian region is analyzed to derive nine ROASHF broadcast coefcients. The performance of the proposed ionospheric broadcast correction model is compared with Klobuchar, NeQuickG, BDS-2, CODEKlob, and CODEGIM TEC models during March and September equinox and June and December solstice days in 2015 and 2016. The mean root mean square error (RMSE) of ROASHF, Klobuchar, NeQuickG, BDS-2, CODEKlob, and CODEGIM TEC models is 7.13 TECU, 9.52 TECU, 15.52 TECU, 11.44 TECU, 13.47 TECU, and 11.97 TECU, respectively. The results demonstrated that the proposed ROASHF ionospheric broadcast model could better predict the ionospheric delays for single-frequency GNSS users. The proposed ionospheric broadcast model is suitable for the Indian regional navigation system known as Navigation with Indian Constellation (NavIC).

6

SuperDARN w Polsce : perspektywy dla badań atmosfery

Odzimek Anna

Przegląd Geofizyczny

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2019

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Z. 3-4

267--286

PL

SuperDARN (Super Dual Auroral Radar Network) jest światową siecią radarów koherentnego rozpraszania w paśmie wysokich częstotliwości HF (High Frequency) do badań górnych warstw atmosfery, mezosfery, jonosfery, termosfery oraz ich sprzężenia z magnetosferą i wiatrem słonecznym. Do głównych tematów badawczych SuperDARN z dziedziny fizyki atmosfery należą echa mezosferyczne, fale planetarne i związane z nimi przemieszczające się zaburzenia jonosferyczne oraz inne przejawy oddziaływania atmosfery neutralnej ze zjonizowaną. W artykule przedstawiamy perspektywy dla rozwoju badań atmosfery z użyciem radarów SuperDARN w kraju, ze szczególnym uwzględnieniem badań z dziedziny elektryczności atmosferycznej.

EN

SuperDARN (Super Dual Auroral Radar Network) is a global network of coherent scatter radars in the HF (High Frequency) band for studying the upper atmosphere, mesosphere, ionosphere, thermosphere and their coupling with the magnetosphere and solar wind. SuperDARN research topics in the field of atmospheric physics include mesospheric echoes, planetary waves and associated travelling ionospheric disturbances, and other manifestations of the interaction of neutral and ionised atmosphere. In the article we present prospects for the development of atmospheric research in Poland using SuperDARN radars, with particular emphasis on research studies in the field of atmospheric electricity.

7

SuperDARN w Polsce – perspektywy

Popielawska Barbara, Odzimek Anna, Doroszkiewicz Joanna, Góral Grzegorz

Przegląd Geofizyczny

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2019

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Z. 3-4

221--251

PL

SuperDARN (Super Dual Auroral Radar Network) jest światową siecią radarów do badania górnych warstw atmosfery, jonosfery i ich sprzężenia z magnetosferą i wiatrem słonecznym (Greenwald i in. 1995; Chisham i in. 2007; Lester 2008, 2013, Nishitani i in. 2019). W artykule przybliżamy szczegóły techniczne, tematy badawcze i publikacje związane z działalnością SuperDARN oraz korzyści płynące z polskiego w nim udziału, który mógłby wzmocnić badania krajowe, jak i współpracę międzynarodową oraz otworzyć nowe tematy badawcze. Zanim to będzie możliwe, należy rozwiązać kilka technicznych kwestii, których tło i perspektywy nakreślamy.

EN

SuperDARN (Super Dual Auroral Radar Network) is a global radar network for studying the upper atmosphere, ionosphere, thermosphere and mesosphere and their coupling with the magnetosphere and solar wind (Greenwald et al. 1995; Chisham et al. 2007; Lester 2008, 2013, Nishitani et al. 2019). In the article we bring closer to national readers the SuperDARN network through describing its technical details, projects and publications. In addition to strengthening present research Polish participation in SuperDARN could result in development of new topics in national research and in international cooperation. Before it is possible, several technical issues should be solved, the background and perspectives of which we outline in the article.

8

Radary SuperDARN : narzędzie do badania i monitorowania atmosfery Ziemi i przestrzeni wokółziemskiej

Góral Grzegorz

Przegląd Geofizyczny

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2019

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Z. 3-4

253--265

PL

Radary SuperDARN powstały jako narzędzie do badań górnych warstw atmosfery i ich związków z magnetosferą i wiatrem słonecznym (Greenwald i in. 1995; Chisham i in. 2007; Lester 2008, 2013). Pracują w zakresie częstotliwości HF, pomiędzy 8 a 20 MHz. Ich zasada działania opiera się na wykorzystaniu rozpraszania Bragga na periodycznych strukturach przestrzennych o skalach odległości porównywalnych z długością fali sondującej. Radary te umożliwiają obserwacje formacji jonosferycznych zorientowanych wzdłuż linii pola geomagnetycznego. W artykule opisano podstawowe bloki funkcjonalne przykładowego radaru SuperDARN: tor nadawczy, odbiorczy oraz system antenowy. Omówiony został sposób modelowania wiązki sondującej. Jedną z kluczowych kwestii przy wyborze lokalizacji dla nowopowstającej stacji SuperDARN jest określenie jej potencjalnych możliwości obserwacyjnych. Można wykorzystać do tego oprogramowanie dokonujące śledzenia dróg propagacji impulsu emitowanego przez radar i określania punktów, w których wektor fali jest prostopadły do lokalnego pola magnetycznego Ziemi. Warunek taki pozwoli na uzyskanie rozproszenia wyemitowanej przez antenę radaru fali z powrotem, w kierunku nadawania. W artykule przedstawiono wyniki symulacji dla hipotetycznej stacji SuperDARN, zlokalizowanej w południowo-zachodniej Polsce. W obliczeniach użyto programu do ray tracingu, bazującego na algorytmie Jones i Stephenson (1975) oraz modelu jonosfery IRI-2012.

EN

SuperDARN radars were developed as a tool for testing the upper atmosphere regions and their coupling with the magnetosphere and solar wind (Greenwald et al. 1995; Chisham et al. 2007; Lester 2008, 2013). They work in the HF frequency range, between 8 and 20MHz. Their principle of operation is based on the use of Bragg scattering on periodic spatial structures with scales of distance comparable to the length of the sounding wave. These radars allow observation of ionospheric formations oriented along the geomagnetic field lines. The article describes basic functional SuperDARN radar blocks: transmitting path, receiving path, and the antenna system as well. The method of modeling the sounding beam is also presented. One of the key issues when choosing a location for a new SuperDARN station is to determine its potential for observation. You can use a special software to track the propagation paths of the pulse emitted by the radar and determining points in which the wave vector is perpendicular to the local geomagnetic field. Such a condition will allow to obtain the scatter of the wave emitted by the radar antenna back into the direc¬tion of transmission. The article presents simulation results for a hypothetical SuperDARN station, located in south-western Poland. The calculation were based on a ray tracing program based on the Jones and Stephenson algorithm (Jones, Stephenson 1975) and the IRI-2012 ionosphere model.

9

Research on GNSS positioning and applications in Poland in 2015–2018

Wielgosz Paweł, Hadaś Tomasz, Kłos Anna, Paziewski Jacek

Geodesy and Cartography

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2019

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Vol. 68, no. 1

87--119

EN

This review paper presents research results on geodetic positioning and applications carried out in Poland, and related to the activities of the International Association of Geodesy (IAG) Commission 4 “Positioning and Applications” and its working groups. It also constitutes the chapter 4 of the national report of Poland for the International Union of Geodesy and Geodynamics (IUGG) covering the period of 2015-2018. The paper presents selected research, reviewed and summarized here, that were carried out at leading Polish research institutions, and is concerned with the precise multi-GNSS (Global Navigation Satellite Systems) satellite positioning and also GNSS-based ionosphere and troposphere modelling and studies. The research, primarily carried out within working groups of the IAG Commission 4, resulted in important advancements that were published in leading scientific journals. During the review period, Polish research groups carried out studies on multi-GNSS functional positioning models for both relative and absolute solutions, stochastic positioning models, new carrier phase integer ambiguity resolution methods, inter system bias calibration, high-rate GNSS applications, monitoring terrestrial reference frames with GNSS, assessment of the real-time precise satellite orbits and clocks, advances in troposphere and ionosphere GNSS remote sensing methods and models, and also their applications to weather, space weather and climate studies.

10

Impact of induced field on the estimation of the ionospheric electric field

Makhlouf S., Djebli M.

Acta Geophysica

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2019

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Vol. 67, no. 6

1671--1677

EN

The ionospheric plasma electric field plays an important role in space physics and space meteorology, and it constitutes an essential physics magnitude for all phenomena occurring in the ionosphere, such as plasma convection, wave–particle interactions, and wave emissions. We used the direct measurements of DEMETER satellite which gives the total electric field, i.e., natural and induced fields, to show the effect of the induced field on the total electric field measurements. For that purpose, the induced electric field, generated by the satellite motion through the Earth’s magnetic lines, is calculated by selecting different velocity satellite and geomagnetic field components. The induced field is calculated by using two different methods: one according to the satellite different axes and the other by using the double-probe method. It is found that the calculated induced electric field dominates on the total electric measurements, therefore leadings to misestimation of the true value of ionospheric electric field.

11

Refrakcja fal radiowych w jonosferze ziemskiej

Wilk-Jakubowski J.

Autobusy : technika, eksploatacja, systemy transportowe

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2017

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R. 18, nr 6

1616--1619, CD

PL

Dokładna znajomość zagadnień dotyczących transmisji fal radiowych w jonosferze jest kluczowa w przypadku projektowania nowych systemów teleinformatycznych z wykorzystaniem satelitów. W artykule omówiony zostanie wpływ uwarunkowań panujących w jonosferze ziemskiej na propagację transjonosferyczną, ze szczególnym uwzględnieniem zjawiska refrakcji fal radiowych oraz scyntylacji. Ponieważ warunkiem niezbędnym propagacji transjonosferycznej jest odpowiednia wartość częstotliwości fali radiowej, na ogół większa niż 30 MHz, uwzględniając izotropowy poziom tła szumów kosmicznych, maksimum i minimum temperatury szumowej promieniowania galaktycznego oraz czynniki takie jak: błąd refrakcji czy scyntylacje jonosferyczne – przyjmuje się, że dolna granica zakresu dogodnego do łączności satelitarnej wynosi 1 GHz. Kolejno wymienione i sklasyfikowane w artykule zjawiska przyczyniły się do optymalnego doboru częstotliwości wykorzystywanych na potrzeby łączności satelitarnej (II okno kosmiczne).

EN

Paper discussed the impact of refraction in the earth’s ionosphere on the propagation of radio waves. Particular attention was paid to the total electron content and irregularities among the propagation paths (one of the effects is ionospheric scintillation). In this context the Author calls attention the frequencies from the second cosmic window.

12

Automatic scaling of critical frequency foF2 from ionograms recorded at São José dos Campos, Brazil: a comparison between Autoscala and UDIDA tools

Pezzopane M., Pillat V. G., Fagundes P. G.

Acta Geophysica

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2017

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Vol. 65, no. 1

173--187

EN

This paper considers a dataset of ionograms recorded by the CADI ionosonde installed at São José dos Campos (SJC; 23.2°S, 45.9°W, magnetic latitude 14.1°S), Brazil, to compare two autoscaling systems: Autoscala, developed by the Istituto Nazionale di Geofisica e Vulcanologia, and the UDIDA-scaling, developed by the Universidade do Vale do Paraíba. The analysis, focused on the critical frequency of the F2 layer, foF2, shows that the two systems work differently. The UDIDA-scaling gives always a value of foF2 as output, regardless of the presence of the ionogram trace and its definition, while Autoscala tends to reject ionograms for which the digital information is considered insufficient. As a consequence, the UDIDA-scaling can autoscale more foF2 values than Autoscala, but Autoscala can discard a larger number of ionograms for which the trace is unidentifiable. Discussions are made on the accuracy of the foF2 values given as output, as well as on the main shortcomings characterizing the two systems.

13

Variability of Ionospheric TEC and the Performance of the IRI-2012 Model at the BJFS Station, China

Li S., Li L., Peng J.

Acta Geophysica

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2016

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Vol. 64, no. 5

1970--1987

EN

We studied variation characteristics of ionospheric total electron contents (TEC) and performance of the International Reference Ionosphere (IRI)-2012 model in predicting TEC at the BJFS (Beijing Fangshan station), China. Diurnal and seasonal variations were analyzed with TEC data derived from dual-frequency global positioning system (GPS) observations along with the solar activity dependence of TEC at the BJFS station. Data interpolated with information from IGS Global Ionosphere Maps (GIMs) were also used in the analysis. Results showed that the IRI-2012 model can reflect the climatic characteristics and solar activity dependence of ionospheric TEC. By using time series decomposition method, ionospheric daily averaged TEC values were divided into the periodic components, geomagnetic activity component, solar activity component and secular trend. Solar activity component and periodic components are supposed to be the main reasons which account for the difference between the GIMs TEC and the TEC from the IRI-2012 model.

14

Statistical Analysis and Modeling of the Local Ionospheric Critical Frequency: A Mid-latitude Single-Station Model for Use in Forecasting

Sapundjiev D., Stankov M. S.

Acta Geophysica

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2016

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Vol. 64, no. 3

810--824

EN

The hourly values of the F-layer critical frequency from the ionospheric sounder in Dourbes (50.1°N, 4.6°E) during the time interval from 1957 to 2010, comprising five solar cycles, were analyzed for the effects of the solar activity. The hourly time series were reduced to hourly monthly medians which in turn were used for fitting a single station foF2 monthly median model. Two functional approaches have been investigated: a statistical approach and a spectral approach. The solar flux F10.7 is used to model the dependence of foF2 on the solar activity and is incorporated into both models by a polynomial expression. The statistical model employs polynomial functions to fit the F-layer critical frequency while the spectral model is based on spectral decomposition of the measured data and offers a better physical interpretation of the fitting parameters. The daytime and nighttime foF2 values calculated by both approaches are compared during high and low solar activity. In general, the statistical model has a slightly lower uncertainty at the expense of the larger number of fitting parameters. However, the spectral approach is superior for modeling the periodic effects and performs better when comparing the results for high and low solar activity. Comparison with the International Reference Ionosphere (IRI 2012) shows that both local models are better at describing the local values of the F-layer critical frequency.

15

Seasonal Variations of Mid-Latitude Ionospheric Trough Structure Observed with DEMETER and COSMIC

Matyjasiak B., Przepiórka D., Rothkaehl H.

Acta Geophysica

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2016

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Vol. 64, no. 6

2734--2747

EN

The mid-latitude ionospheric trough is a depleted region of ionospheric plasma observed in the topside ionosphere. Its behavior can provide useful information about the magnetospheric dynamics, since its existence is sensitive to magnetospherically induced motions. Midlatitude trough is mainly a night-time phenomenon. Both, its general features and detailed characteristics strongly depend on the level of geomagnetic disturbances, time of the day, season, and the solar cycle, among others. Although many studies provide basic information about general characteristics of the main ionospheric trough structure, an accurate prediction of the trough behavior in specific events is still understood poorly. The paper presents the mid-latitude trough characteristics with regard to the geomagnetic longitude and season during a solar activity minimum, as based on the DEMETER in situ satellite measurements and the data retrieved from FORMOSAT-3/COSMIC radio occultation measurements.

16

Prospects for Solar and Space Weather Research with Polish Part of the LOFAR Telescope

Dąbrowski B. P., Krankowski A., Błaszkiewicz L., Rothkaehl H.

Acta Geophysica

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2016

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Vol. 64, no. 3

825--840

EN

The LOw-Frequency ARray (LOFAR) is a new radio interferometer that consists of an array of stations. Each of them is a phase array of dipole antennas. LOFAR stations are distributed mostly in the Netherlands, but also throughout Europe. In the article we discuss the possibility of using this instrument for solar and space weather studies, as well as ionosphere investigations. We are expecting that in the near future the LOFAR telescope will bring some interesting observations and discoveries in these fields. It will also help to observe solar active events that have a direct influence on the near-Earth space weather.

17

Mid-Latitude Single Station F region Storm Morphology and Forecast

Cander L. R.

Acta Geophysica

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2016

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Vol. 64, no. 2

541--566

EN

This paper describes certain aspects of the F region storm morphology based on vertical incidence measurements at single ionosonde station Chilton (51°.60′N, 358°.70′E). The topics discussed include requirements for better understanding of the ionospheric F region morphology and its forecasting under geomagnetically quiet and disturbed conditions. A few common storms during the years of low (1996 and 1997) and high (2000 and 2001) solar activity are considered as well as the Short-Term Ionospheric Forecasting (STIF) method by using two representative examples. The merits are stressed of near-real-time use of data to provide more accurate specification of the geomagnetically disturbed ionosphere and forecast its structure few hours in advance.

18

An Empirical Model for the Ionospheric Global Electron Content Storm-Time Response

Li S., Galas R., Ewert D., Peng J.

Acta Geophysica

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2016

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Vol. 64, no. 1

253--269

EN

By analyzing the variations of global electron content (GEC) during geomagnetic storm events, the ratio “GEC/GECQT” is found to be closely correlated with geomagnetic Kp index and time weighted Dst index, where GECQT is the quiet time reference value. Moreover, the GEC/GECQT will decrease with the increase of the solar flux F10.7 index. Furthermore, we construct a linear model for storm-time response of GEC. Eighty-two storm events during 1999-2011 were utilized to calculate the model coefficients, and the performance of the model was tested using data of 8 storm events in 2012 by comparing the outputs of the model with the observed GEC values. Results suggest that the model can capture the characteristics of the GEC variation in response to magnetic storms. The component describing the solar activity influence shows a counteracting effect with the geomagnetic activity component; and the influence of Kp index causes an increase of GEC, while the time weighted Dst index causes a decrease of GEC.

19

Wykorzystanie formatu ionex do poprawy pozycjonowania na obszarze powiatu ryckiego

Krasuski K.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2015

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nr 2

30--34

PL

W artykule przedstawiono wyniki badań dotyczących poprawy pozycjonowania absolutnego na obszarze powiatu ryckiego. W ramach eksperymentu wykorzystano obserwacje kodowe GPS ze stacji referencyjnej RYKI. Współrzędne stacji referencyjnej RYKI zostały wyznaczone na dwa sposoby w programie RTKLIB, przy zastosowaniu metody punktowego pozycjonowania absolutnego. W pierwszym teście poprawka jonosferyczna została określona za pomocą modelu Klobuchara, zaś w drugim teście mapy jonosfery VTEC w formacie IONEX zostały zaimplementowane do obliczeń. Wstępne wyniki dokładnościowe pozycjonowania podkreślają tezę o potrzebie asymilacji lokalnego modelu jonosfery do poprawy pozycjonowania. Parametry jonosfery VTEC w teście II poprawiają dokładność pozycji nawet do 8 m, w porównaniu z testem I. Dodatkowo błąd RMS-3D został obliczony i osiąga wartości do ponad 11 m.

EN

Article presents studies results regard to standalone positioning correction over Ryki District area. In the experiment GPS code observations from RYKI reference station were utilized. Station coordinates were estimated based on two ways in RTKLIB software using Single Point Positioning mathematical formulation. In first test ionosphere delay was determinated using Klobuchar model, but in second case ionosphere VTEC maps were implemented in computations also. Preliminary results of positioning accuracy underline thesis that local ionosphere model should be assimilated to positioning correction. Ionosphere VTEC parameters in test II improves positioning accuracy to 8 m, in comparison to test I. Additionally RMS-3D error was calculated and it can reach up to 11 m.

20

Positioning and applications

Rogowski J. B., Wielgosz P.

Geodesy and Cartography

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2015

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Vol. 64, no. 2

243--259

EN

The paper presents national report of Poland for IAG on positioning and applications. The selected research presented was carried out at leading Polish research institutions and concern precise multi-GNSS satellite positioning - relative and absolute - and also GNSS-based ionosphere and troposphere modelling and studies. The research resulted in noticeable advancements in these subjects confirmed by the development of new algorithms and methods. New and improved methods of precise GNSS positioning were developed, and also GNSS metrology was studied. New advanced troposphere models were presented and tested. In particular, these models allowed testing IPW variability on regional and global scales. Also, new regional ionosphere monitoring web-based services were developed and launched.