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EN
We present in detail the algorithm of the electrostatic–quasi-stationary–electromagnetic/MHD approximations and equivalent external sources (EQUEMES method) to develop the quasi-stationary–electromagnetic models of seismo-ionospheric coupling. The penetration of the electromagnetic feld created by near-Earth alternative currents of ULF range was simulated by solving equations for the horizontal electric feld components Ex, Ey of the second order with respect to the vertical coordinate z. This system of two second-order equations is derived from the system of Maxwell equations. The penetration of rather strong horizontal electric feld [of order of (1–10) mV/m] to the ionospheric E and F layers has been modeled. The corresponding variations in the electron concentration in the E and lower F layers of the ionosphere reach a value of order of (1–10)%. Farther increase in these variations can be connected with the related synergetic processes. A possibility of the efective initiation of electron concentration perturbations in the unstable near-equatorial plasma in the F layer of the ionosphere by the packet of atmospheric gravity waves radiated by the near-ground source is illustrated. A good correspondence of the results obtained on the basis of this model to the data of satellite observations is shown.
EN
Proper characterization of total electron content (TEC) and scintillation is very important to global positioning system (GPS) users in communication, navigation, ionospheric or atmospheric studies. Quiet time variation of TEC is useful in the estimation and removal of ionospheric delay for global navigation satellite systems single-frequency positioning. During geomagnetic storms, the variations of ionosphere deviate from their quiet day pattern and can cause significant effects on short-term prediction of various ionospheric parameters. The dynamics of the ionosphere change from region to region; therefore, in order to evaluate and improve the performance of global models of the ionosphere, numerous studies of variations using measured ionospheric parameters from stations globally are useful. This paper presents for the first time variations in the TEC and scintillation at Maseno University (geomagnetic coordinates, 9.64°S, 108.59°E), Kenya, investigated using a NovAtelGSV400B GPS receiver for the high solar activity year 2014. The GPS-measured TEC values were compared with the modeled TEC values by the latest International Reference Ionosphere model (IRI-2016), with a view to evaluate the performance of this version of the model. The largest TEC values were observed from 1300 to 1500 h local time throughout the year with the largest diurnal values occurring in March equinox and smallest during June solstice. The largest TEC values are attributed to extreme ultraviolet radiation coupled with upward →E ×→B plasma drift velocity. Nighttime enhancements in TEC attributed to the ‘fountain’ effect occurred during some months. Scintillation correlated with depletions in TEC occurred in the period between 1600 h local time to 1900 h local time (post-sunset) sector during some months, with the strongest value of − 0.91 being experienced in March equinox. Scintillation was absent during geomagnetic storms studied mainly as a result of the time of onset of the recovery phases of the storms. In addition, the geomagnetic storms were manifested in GPS-measured TEC as negative ionospheric storms. The IRI-2016 model gave a good prediction of measured values except for its overestimation of measured TEC in the months of May and June. Further, a new insight shown by the results is the ability of the IRI-2016 model to predict post-sunset TEC enhancements during some months contrary to previous versions reported by other researchers in East Africa. However, model is not quickly sensitive to transitions from one season to another. This result contributes to the improvement of the current IRI model by recommending the introduction of an input into the model that is sensitive to transitions in seasons in future versions of the model.
EN
In radioastronomy the interferometric measurement between radiotelescopes located relatively close to each other helps removing ionospheric effects. Unfortunately, in case of networks such as LOw Frequency ARray (LOFAR), due to long baselines (currently up to 1500 km), interferometric methods fail to provide sufficiently accurate ionosphere delay corrections. Practically it means that systems such as LOFAR need external ionosphere information, coming from Global or Regional Ionospheric Maps (GIMs or RIMs, respectively). Thanks to the technology based on Global Navigation Satellite Systems (GNSS), the scientific community is provided with ionosphere sounding virtually worldwide. In this paper we compare several interpolation methods for RIMs computation based on scattered Vertical Total Electron Content measurements located on one thin ionospheric layer (Ionospheric Pierce Points—IPPs). The results of this work show that methods that take into account the topology of the data distribution (e.g., natural neighbour interpolation) perform better than those based on geometric computation only (e.g., distance-weighted methods).
EN
An ionospheric model and corresponding coefficients broadcasted via GNSS navigation message are generally used to estimate the time delay for single-frequency GNSS users. In this article, the capabilities of three ionospheric models, namely, Klobuchar model, NeQuick Galileo version (NeQuick G), and Neustrelitz TEC broadcast model (NTCM-BC), were assessed. The models were examined in two aspects: total electron content (TEC) prediction and ionospheric delay correction effects in single-point positioning. Results show that both NeQuick G and NTCM-BC models outperformed Klobuchar model for predicting global TEC values during all the test days. Compared with Slant TEC (STEC) along the receiver-to-satellite ray path derived from IGS global ionosphere map (GIMs), STEC from NeQuick G and NTCM-BC models tend to have less bias than those from Klobuchar model in most situations. The point positioning results were improved by applying ionospheric broadcast models especially at the mid- and low-latitude stations.
PL
W artykule omówiono zjawisko Peltiera z naciskiem na analizę modelu matematycznego opisującego zjawiska zachodzące na elemencie półprzewodnikowym odpowiedzialnym za regulacje temperatury. Zaprezentowany model matematyczny wykorzystany do opracowania programów symulacyjnych, z których uzyskane wyniki zaprezentowano w końcowej części referatu. Przedstawiono również opis możliwości wykorzystania ogniw Peltiera jako elementów wspomagających układ klimatyzacyjny w autobusach.
EN
Article shows the Peltier effect with emphasis on the analysis of the mathematical model describing the phenomena on semiconductor element responsible for regulating the temperature. Presented mathematical model used to develop simulation programs, of which the results were presented in the final part of the paper. Also contains a description of the possibilities of using a Peltier element supporting the air conditioning system in the buses.
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.
EN
This work describes new method to determine parameters of Peltier module. Classical method requires module to be disassembled, rendering it useless after the experiment. Described new method does not require interference in structure of the module allowing it to be used after experiment. This is helpful in designing of new modules, where there is few samples to test.
PL
Praca opisuje nową metodę wyznaczania parametrów modułów Peltiera. Metody klasyczne wymagają rozmontowania modułu, co powoduje jego zniszczenie. Prezentowana metoda zapewnia precyzyjny pomiar parametrów modułu Peltiera bez konieczności ingerencji w jego fizyczną strukturę. Jest ona szczególnie pomocna przy wytwarzaniu i testowaniu modułów prototypowych.
EN
The article presents research conducted by means of the GPS technique through TEC (Total Electron Content) computation for individual satellites. The proposed method makes it possible to investigate small ionospheric structures. For strong ionospheric disturbances, at high and middle latitudes, one can observe a ionospheric trough shift towards the lower latitudes. The results presented in this paper were obtained for strong disturbances observed in October 2003. The paper shows a comparison for chosen quiet and strongly disturbed days. To avoid differences caused by changing position of the Sun (seasonal zenith angle changes), all the analysed information was related to the same period of time.
EN
The conjugacy effects of the GPS scintillation activities during the geomagnetic storms of October 2003, November 2003 and July 2004 have been investigated at the approximately geomagnetically conjugate stations: Scott Base, Antarctica (SBA) and Resolute Cornwallis Island (RESO) in the high Arctic region. The measurements aim at investigation of the similarities and differences of the scintillation activities occurring at the conjugate points in the polar regions under storm conditions and examine the relationship between the Storm Enhanced Density (SED) and scintillation activity. The measurements of the scintillation activities obtained from total scintillation index during these storm periods at both hemispheres showed asymmetry in the ionospheric scintillation occurrence at the conjugate points. Pronounced scintillation activity was observed at the nightside hemisphere with the total scintillation index higher than at the dayside hemisphere. The results also show that the durations of severe scintillation activity were longer at the nightside hemisphere. The measurements showed that the intense scintillation periods were corresponding to the presence of the SED events where more pronounced SED events were observed over the nightside hemisphere.
EN
Many applications of HF propagation via the ionosphere (e.g. bearing-fingers, single station location, emergency systems and so on) demand an accurate description of ionospheric conditions. The International Reference Ionosphere (IRI) model is very often used for such a description. A lot of publications were devoted to the verification and improvement of this model. But most of them were based on data from vertical sounding (VS). Not so many comparisons with oblique sounding results have been reported. Specifically, this concerns parameters of the maximum usable frequency (MUF) and a ground range, D. In this paper errors of MUF and D determination by means of the IRI model are estimated on the example of the MOF data on Inskip–Rome path for December 2003. Adaptation of the model to current conditions by means of VS and total electron content TEC-GPS data is used to reduce these errors.
EN
This paper outlines the effect of horizontal ionospheric gradients on transionospheric path propagation such as for the case of GPS signals. The total electron content (TEC) is a function of time of day, and is much influenced by solar activity and also the receiving station location. To make the model applicable for long baselines, for which the ionosphere is not generally well correlated between receiving stations, the ionospheric gradients should be taken into account. In this work the signal path is determined using a modified ray-tracing technique together with a homing-in method. Results show that horizontal gradients can have a significant effect on GPS positioning for both single station positioning and differential GPS. For differential GPS, the ionospheric delay can, however, be either increased or decreased compared with the case of no gradient, depending on the gradient direction.
12
Content available remote Impact of tec fluctuations in the Antarctic ionosphere on GPS positioning
EN
With increasing reliance on space-based platforms for global navigation and communication, concerns about the impact of ionospheric scintillation and total electron content fluctuations on these systems have became a high priority. In this paper, GPS transionospheric signals have been used to study the development of ionospheric phase fluctuations observed at Antarctic IGS permanent stations: McMurdo-MCM4, Casey-CAS1, Mawson-MAW1, Sanae-VESL, Syowa-SYOG and Davis-DAV1 in 2001. The use of the multi-station, multi-path observations of the GPS beacons has allowed the study of the time development of irregularities as a function of latitude and longitude of individual geomagnetic storms. The basic storms studied were those of March 19-20, March 31, April 9-11, June 16-17, and September 23, 2001. The rate of TEC (ROT) parameter was used to study the occurrence of TEC fluctuations. The results from studying these storms showed the unique nature of each storm. For the above five storms, data were available from three auroral stations (VESL, SYOG and MAW1) and from 61° to 70° Corrected Geomagnetic Latitude (CGL). In addition, data from three higher latitude polar stations (DAV1, MCM4 and CAS1) near 800 CGL are also analysed. Fluctuation effects, causing dramatic changes in total electron content – TEC, can have a different impact on GPS positioning accuracy (especially during phase ambiguity resolution). Bernese ver.4.2 software was used for the analysis of the GPS permanent data from Antarctic IGS stations. The analyses rely on studying the repeatability of vector co-ordinates. These vectors were investigated during the geomagnetic storms when the intensity of TEC fluctuations was more pronounced. The impact of TEC fluctuations in the high latitude ionosphere on GPS positioning accuracy has been discussed in terms of the total number of observations of doubledifferences (DD) and in the ratio of the total number of all ambiguities to unresolved ones.
EN
GPS observations of the European permanent network were used to identify seismoionospheric precursors of Baltic Sea earthquake of 21 September 2004. It is a very rare event for this region of Europe (magnitude of about 5.0). This value is the threshold for the occurrence of seismic effects in the ionosphere. In total electron content (TEC) data over the region of the earthquake, a specific ionospheric anomaly appeared one day before the earthquake was detected. The ionospheric variability had a positive sign with an enhancement of about 4-5 TECU (1 TECU = 1016 electrons/m2) relative to the non-disturbed state of the ionosphere. The anomaly had a duration of 4-5 hours in the day time. The special size of this anomaly was about 1000 km. The characteristic parameters of the anomaly show that it can be associated with ionospheric precursors of an earthquake.
PL
W pracy przedstawiono wyniki badań nad wykorzystaniem ciągłych obserwacji GPS ze stacji uczestniczących w międzynarodowym programie IGS (International GPS Service) do monitorowania wektorów w rejonie okołobiegunowym, których punkty są położone na różnych strukturach tektonicznych. Analizie poddano okres od 1996 r. (minimalna aktywność słoneczna) do 2001 r. (maksymalna aktywność słoneczna). Obserwacje opracowano za pomocą softwaru Bernese ver. 4.2. na podstawie całodobowych permanentnych obserwacji GPS. Prowadzone równolegle z monitorowaniem stanu jonosfery wyznaczenia dzień po dniu współrzędnych wektora łączącego stację Onsala (57,3°N, 11,9°E) z NyAlesund (78,9°N, 11,9°E) pozwoliły ujawnić wyraźną korelację między zmianami wartości TEC (Total Electron Content) występującymi w okresie spokojnej i zaburzonej jonosfery a zmianami wartości współrzędnych wektora o długości ponad 2300 km.
EN
The results of the analyses of IGS (International GPS Service) permanent observations to monitor GPS vectors, located at different tectonic platforms, in Arctic region are presented.GPS permanent observations Onsala (57,3°N, 11,9°E) and NyAlesund (78,9°N, 11,9°E) from 1996 (low solar activity) to 2001 (maximum solar activity) were analyzed. Software Bernese ver.4.2 was used for the analysis of the GPS observational data of 24-hour sessions. The ionspheric storms have considerable influence on the accuracy determination of the Onsala-Nyalesund vector coordinates. The results show exact dependence between TEC changes during quiet and disturbed ionospheric conditions and the repeatability of the vectors' coordinates and the length of the baselines, even for vectors longer than 2 300 km.
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