Gotowe bibliografie tematyczne / Ionospheic wave propagation

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Gotowa bibliografia na temat „Ionospheic wave propagation”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "Ionospheic wave propagation"

Yang, Li-Xia, Chao Liu, Qing-Liang Li i Yu-Bo Yan. "Electromagnetic wave propagation characteristics of oblique incidence nonlinear ionospheric Langmuir disturbance". Acta Physica Sinica 71, nr 6 (2022): 064101. http://dx.doi.org/10.7498/aps.71.20211204.

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Based on the generalized Zakharov model, a numerical model of electromagnetic wave propagating in the ionosphere at different angles is established by combining the finite difference time domain (FDTD) method of obliquely incident plasma with the double hydrodynamics equation and through equivalently transforming the two-dimensional Maxwell equation into one-dimensional Maxwell equation and the plasma hydrodynamics equation. In this paper. the dominant equation of Z-wave in obliquely incident nonlinear ionospheric plasma having been analyzed and deduced, the FDTD algorithm suitable for calculating the propagation characteristics of ionospheric electromagnetic wave is deduced. The simulation results prove the accuracy and effectiveness of this method for the Langmuir disturbance caused by electromagnetic wave heating the ionosphere at a small inclination angle. The results show that under small angle incidence, the high-power high-frequency electromagnetic wave excites the Langmuir wave near the O-wave reflection point in the ionospheric plasma. At the same time, the wave particle interaction causes the O-wave to convert into Z-wave and propagate into the higher region of the ionosphere. In this work, the electromagnetic wave propagation characteristics are further studied based on ionospheric plasma, which is helpful in laying the foundation of numerical algorithm for comprehensively and in depth analyzing the influence of ionospheric Langmuir disturbance on ionospheric radio wave propagation characteristics.

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Ueda, H. O., Y. Omura i H. Matsumoto. "Computer simulations for direct conversion of the HF electromagnetic wave into the upper hybrid wave in ionospheric heating experiments". Annales Geophysicae 16, nr 10 (31.10.1998): 1251–58. http://dx.doi.org/10.1007/s00585-998-1251-y.

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Abstract. Excitation of upper hybrid waves associated with the ionospheric heating experiments is assumed to be essential in explaining some of the features of stimulated electromagnetic emissions (SEE). A direct conversion process is proposed as an excitation mechanism of the upper hybrid waves where the energy of an obliquely propagating electromagnetic pump wave is converted into the electrostatic upper hybrid waves due to small-scale density irregularities. We performed electromagnetic particle-in-cell simulations to investigate the energy conversion process in the ionospheric heating experiments. We studied dependence of the amplitude of the excited wave on the propagation angle of the pump wave, scale length of the density irregularity, degree of the irregularity, and thermal velocity of the plasma. The maximum amplitude is found to be 37 of the pump amplitude under an optimum condition.Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; wave-particle interactions).

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Mabie, Justin, i Terence Bullett. "Multiple Cusp Signatures in Ionograms Associated with Rocket-Induced Infrasonic Waves". Atmosphere 13, nr 6 (12.06.2022): 958. http://dx.doi.org/10.3390/atmos13060958.

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We are interested in understanding how and when infrasonic waves propagate in the thermosphere, specifying the physical properties of those waves, and understanding how they affect radio wave propagation. We use a combination of traditional ionosonde observations and fixed frequency Doppler soundings to make high quality observations of vertically propagating infrasonic waves in the lower thermosphere/bottom side ionosphere. The presented results are the first simultaneous observations of infrasonic wave-induced deformations in ionograms and high-time-resolution observations of corresponding plasma displacements. Deformations in ionospheric echoes, which manifest as additional cusps and range variations, are shown to be caused by infrasonic wave-induced plasma displacements.

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Leyser, Thomas B., H. Gordon James, Björn Gustavsson i Michael T. Rietveld. "Evidence of <i>L</i>-mode electromagnetic wave pumping of ionospheric plasma near geomagnetic zenith". Annales Geophysicae 36, nr 1 (21.02.2018): 243–51. http://dx.doi.org/10.5194/angeo-36-243-2018.

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Abstract. The response of ionospheric plasma to pumping by powerful HF (high frequency) electromagnetic waves transmitted from the ground into the ionosphere is the strongest in the direction of geomagnetic zenith. We present experimental results from transmitting a left-handed circularly polarized HF beam from the EISCAT (European Incoherent SCATter association) Heating facility in magnetic zenith. The CASSIOPE (CAScade, Smallsat and IOnospheric Polar Explorer) spacecraft in the topside ionosphere above the F-region density peak detected transionospheric pump radiation, although the pump frequency was below the maximum ionospheric plasma frequency. The pump wave is deduced to arrive at CASSIOPE through L-mode propagation and associated double (O to Z, Z to O) conversion in pump-induced radio windows. L-mode propagation allows the pump wave to reach higher plasma densities and higher ionospheric altitudes than O-mode propagation so that a pump wave in the L-mode can facilitate excitation of upper hybrid phenomena localized in density depletions in a larger altitude range. L-mode propagation is therefore suggested to be important in explaining the magnetic zenith effect. Keywords. Space plasma physics (active perturbation experiments)

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Pokhotelov, O. A., M. Parrot, E. N. Fedorov, V. A. Pilipenko, V. V. Surkov i V. A. Gladychev. "Response of the ionosphere to natural and man-made acoustic sources". Annales Geophysicae 13, nr 11 (30.11.1995): 1197–210. http://dx.doi.org/10.1007/s00585-995-1197-2.

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Abstract. A review is presented of the effects influencing the ionosphere which are caused by acoustic emission from different sources (chemical and nuclear explosions, bolides, meteorites, earthquakes, volcanic eruptions, hurricanes, launches of spacecrafts and flights of supersonic jets). A terse statement is given of the basic theoretical principles and simplified theoretical models underlying the physics of propagation of infrasonic pulses and gravity waves in the upper atmosphere. The observations of "quick" response by the ionosphere are pointed out. The problem of magnetic disturbances and magnetohydrodynamic (MHD) wave generation in the ionosphere is investigated. In particular, the supersonic propagation of ionospheric disturbances, and the conversion of the acoustic energy into the so-called gyrotropic waves in the ionospheric E-layer are considered.

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Waters, C. L., T. K. Yeoman, M. D. Sciffer, P. Ponomarenko i D. M. Wright. "Modulation of radio frequency signals by ULF waves". Annales Geophysicae 25, nr 5 (4.06.2007): 1113–24. http://dx.doi.org/10.5194/angeo-25-1113-2007.

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Abstract. The ionospheric plasma is continually perturbed by ultra-low frequency (ULF; 1–100 mHz) plasma waves that are incident from the magnetosphere. In this paper we present a combined experimental and modeling study of the variation in radio frequency of signals propagating in the ionosphere due to the interaction of ULF wave energy with the ionospheric plasma. Modeling the interaction shows that the magnitude of the ULF wave electric field, e, and the geomagnetic field, B0, giving an e×B0 drift, is the dominant mechanism for changing the radio frequency. We also show how data from high frequency (HF) Doppler sounders can be combined with HF radar data to provide details of the spatial structure of ULF wave energy in the ionosphere. Due to spatial averaging effects, the spatial structure of ULF waves measured in the ionosphere may be quite different to that obtained using ground based magnetometer arrays. The ULF wave spatial structure is shown to be a critical parameter that determines how ULF wave effects alter the frequency of HF signals propagating through the ionosphere.

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Husin, Asnawi, i Buldan Muslim. "EFEK GELOMBANG TSUNAMI ACEH 2004 PADA GANGGUAN IONOSFER BERGERAK SKALA MENENGAH DARI PENGAMATAN JARINGAN GPS SUMATRA". Komunikasi Fisika Indonesia 16, nr 2 (31.10.2019): 130. http://dx.doi.org/10.31258/jkfi.16.2.130-137.

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Medium Scale Travelling Ionospheric Disturbance (MSTID), thought to be manifestation of atmospheric gravity wave (AGW) in the ionospheric altitude that propagates horizontally and effects on in the electron density structure of ionosphere. These atmospheric gravity waves sourced from lower atmospheric activities such as typhoons, volcanic eruptions and tsunamis. Wave energy by its coupling induction process can travel to the ionosphere region. It has been understood that the TID's wave structure have an impact on the propagation of radio waves in the ionosphere so that it will affect the performance of navigation satellite-based positioning measurements. Based on Aceh tsunami in December 2004, this study aimed to investigation of the induction of atmospheric gravity waves in the ionosphere using total electron content (TEC) data from the Sumatra GPS network (Sumatra GPS Array, SUGAR). The detection technique of TEC changes due to AGW induction with a filter to separate medium scale disturbance at the ionospheric pierce point at an altitude of 350 km (IPP, Ionospheric Pierce Point). The results show the horizontal wavelength of a medium-scale TID around 180 ± 12 Km with a velocities of around 376 ± 9 ms-1. Based on two-dimensional map, the TID moves to the southeast.

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Li, Qingfeng, Zeyun Li i Hanxian Fang. "Using 3D Ray Tracing Technology to Study the Disturbance Effect of Rocket Plume on Ionosphere". Atmosphere 13, nr 7 (20.07.2022): 1150. http://dx.doi.org/10.3390/atmos13071150.

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In this paper, the initial neutral atmospheric parameters, background ionospheric parameters and geomagnetic field parameters of the ionosphere are obtained by NRLMSISE-00 model, IRI-2016 model and IGRF-13 model, respectively. Considering the neutral gas diffusion process, ion chemical reaction and plasma diffusion process, a three-dimensional dynamic model of chemical substances released by rocket plume disturbing the ionosphere is constructed. The influence of the disturbance on the echo path of high frequency radio waves with different incident frequencies is simulated by using three-dimensional digital ray-tracing technology. Using this model, the process of ionospheric disturbance caused by the main chemical substances H2 and H2O in the rocket plume under three different release conditions: fixed-point release at 300 km, vertical path at 250–350 km and parabolic path at 250–350 km, and the influence of the ionospheric cavity on the radio wave propagation of high frequency radio waves at different frequencies are simulated. The main purpose of the article is to focus on the effect of the cavity generated by the rocket exhaust on the propagation of radio waves. It mainly studies the perturbation effect on the ionosphere under different release conditions, considers the neutral gas diffusion process, ion chemical reaction and plasma diffusion process, and establishes the three-dimensional dynamics of the ionospheric electron density and the spatiotemporal distribution of the plume plasma learning model. Finally, the three-dimensional ray-tracing algorithm is used to simulate the propagation path of the radio wave through the disturbance area. We considered three different release conditions, including fixed-point release, vertical path and parabolic path. The ionospheric disturbances produced by these different releases are compared and analyzed, and their effects on the propagation path of radio waves are studied.

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Hoffmann, P., i Ch Jacobi. "Planetary wave characteristics of gravity wave modulation from 30–130 km". Advances in Radio Science 10 (19.09.2012): 271–77. http://dx.doi.org/10.5194/ars-10-271-2012.

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Abstract. Fast gravity waves (GW) have an important impact on the momentum transfer between the middle and upper atmosphere. Experiments with a circulation model indicate a penetration of high phase speed GW into the thermosphere as well as an indirect propagation of planetary waves by the modulation GW of momentum fluxes into the thermosphere. Planetary wave characteristics derived from middle atmosphere SABER temperatures, GW potential energy and ionospheric GPS-TEC data at midlatitudes reveal a possible correspondence of PW signatures in the middle atmosphere and ionosphere in winter around solar maximum (2002–2005). In the case of the westward propagating 16-day wave with zonal wavenumber 1 a possible connection could be found in data analysis (November–December 2003) and model simulation. Accordingly, GW with high phase speeds might play an essential role in the transfer of PW and other meteorological disturbances up to the ionospheric F-region.

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Liu, Tong, Zhibin Yu, Zonghua Ding, Wenfeng Nie i Guochang Xu. "Observation of Ionospheric Gravity Waves Introduced by Thunderstorms in Low Latitudes China by GNSS". Remote Sensing 13, nr 20 (15.10.2021): 4131. http://dx.doi.org/10.3390/rs13204131.

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The disturbances of the ionosphere caused by thunderstorms or lightning events in the troposphere have an impact on global navigation satellite system (GNSS) signals. Gravity waves (GWs) triggered by thunderstorms are one of the main factors that drive short-period Travelling Ionospheric Disturbances (TIDs). At mid-latitudes, ionospheric GWs can be detected by GNSS signals. However, at low latitudes, the multi-variability of the ionosphere leads to difficulties in identifying GWs induced by thunderstorms through GNSS data. Though disturbances of the ionosphere during low-latitude thunderstorms have been investigated, the explicit GW observation by GNSS and its propagation pattern are still unclear. In this paper, GWs with periods from 6 to 20 min are extracted from band-pass filtered GNSS carrier phase observations without cycle-slips, and 0.2–0.8 Total Electron Content Unit (TECU) magnitude perturbations are observed when the trajectories of ionospheric pierce points fall into the perturbed region. The propagation speed of 102.6–141.3 m/s and the direction of the propagation indicate that the GWs are propagating upward from a certain thunderstorm at lower atmosphere. The composite results of disturbance magnitude, period, and propagation velocity indicate that GWs initiated by thunderstorms and propagated from the troposphere to the ionosphere are observed by GNSS for the first time in the low-latitude region.

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Rozprawy doktorskie na temat "Ionospheic wave propagation"

Tshisaphungo, Mpho. "Validation of high frequency propagation prediction models over Africa". Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1015239.

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The ionosphere is an important factor in high frequency (HF) radio propagation providing an opportunity to study ionospheric variability as well as the space weather conditions under which HF communication can take place. This thesis presents the validation of HF propagation conditions for the Ionospheric Communication Enhanced Profile Analysis and Circuit (ICEPAC) and Advanced Stand Alone Prediction System (ASAPS) models over Africa by comparing predictions with the measured data obtained from the International Beacon Project (IBP). Since these models were not developed using information on the African region, a more accurate HF propagation prediction tool is required. Two IBP transmitter stations are considered, Ruaraka, Kenya (1.24°S, 36.88°E) and Pretoria, South Africa (25.45°S, 28.10°E) with one beacon receiver station located in Hermanus, South Africa (34.27°S, 19.l2°E). The potential of these models in terms of HF propagation conditions is illustrated. An attempt to draw conclusions for future improvement of the models is also presented. Results show a low prediction accuracy for both ICEPAC and ASAPS models, although ICEPAC provided more accurate predictions for daily HF propagation conditions. This thesis suggests that the development of a new HF propagation prediction tool for the African region or the modification of one of the existing models to accommodate the African region, taking into account the importance of the African ionospheric region, should be considered as an option to ensure more accurate HF Propagation predictions over this region.

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Löfås, Henrik. "Ionospheric modification by powerful HF-waves : Underdense F-region heating by X-Mode". Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-121898.

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Observations of modifications of the electron temperature in the F-region produced by powerful high-frequency waves transmitted in X-mode are presented. The experiments were performed during quiet nighttime conditions with low ionospheric densities so no reflections occurred. Nevertheless temperature enhancements of the order of 300-400K were obtained. The modifications found can be well described by the theory of Ohmic heating by the pump wave and both temporal and spatial changes are reproduced. A brief overview of several different experimental campaigns at EISCAT facilities in the period from October 2006 to February 2008 are also given pointing out some interesting features from the different experiments. The main focus is then on the campaign during October 2006 and modifications of the electron temperature in the F-region.

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De, Larquier Sebastien. "The mid-latitude ionosphere under quiet geomagnetic conditions: propagation analysis of SuperDARN radar observations from large ionospheric perturbations". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/24770.

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The Earth's ionosphere is a dynamic environment strongly coupled to the neutral atmosphere, magnetosphere and solar activity. In the context of this research, we restrict our interest to the mid-latitude (a.k.a., sub-auroral) ionosphere during quiet geomagnetic conditions. The Super Dual Auroral Radar Network (SuperDARN) is composed of more than 30 low-power High Frequency (HF, from 8-18 MHz) Doppler radars covering the sub-auroral, auroral and polar ionosphere in both hemispheres. SuperDARN radars rely on the dispersive properties of the ionosphere at HF to monitor dynamic features of the ionosphere. Though originally designed to follow auroral expansion during active periods, mid-latitude SuperDARN radars have observed ground and ionospheric scatter revealing several interesting features of the mid-latitude ionosphere during periods of moderate to low geomagnetic activity. The past 7 years' expansion of SuperDARN to mid-latitudes, combined with the recent extended solar minimum, provides large-scale continuous views of the sub-auroral ionosphere for the first time. We have leveraged these circumstances to study prominent and recurring features of the mid-latitude ionosphere under quiet geomagnetic conditions. First, we seek to establish a better model of HF propagation effects on SuperDARN observations. To do so, we developed a ray-tracing model coupled with the International Reference Ionosphere (IRI). This model is tested against another well established ray-tracing model, then optimized to be compared to SuperDARN observations (Chapter 2). The first prominent ionospheric feature studied is an anomaly in the standard ionospheric model of photo-ionization and recombination. This type of event provides an ideal candidate for testing the ray-tracing model and analyzing propagation effects in SuperDARN observations. The anomaly was first observed in ground backscatter occurring around sunset for the Blackstone, VA SuperDARN radar. We established that it is related to an unexpected enhancement in electron densities that leads to increased refraction of the HF signals. Using the ray-tracing, IRI model, and measurements from the Millstone Hill Incoherent Scatter Radar (ISR), we showed that this enhancement is part of a global phenomenon in the Northern Hemisphere, and is possibly related to the Southern Hemisphere's Weddell Sea Anomaly. We also tested a potential mechanism involving thermospheric winds and geomagnetic field configuration which showed promising results and will require further modeling to confirm (Chapter 3). The second ionospheric feature was a type of decameter-scale irregularity associated with very low drift velocities. Previous work had established that these irregularities occur throughout the year, during nighttime, and equatorward of both the auroral regions and the plasmapause boundary. An initial analysis suggested that the Temperature Gradient Instability (TGI) was responsible for the growth of such irregularities. We first used our ray-tracing model to distinguish between HF propagation effects and irregularity occurrence in SuperDARN observations. This revealed the irregularities to be widespread within the mid-latitude ionosphere and located in the bottom-side F-region (Chapter 4). A second study using measurements from the Millstone Hill ISR revealed that TGI driven growth was possible but only in the top-side F-region ionosphere. We found that initial growth may occur primarily at larger wavelengths, with subsequent cascade to decameter-scale with coupling throughout the F-region (Chapter 5). In summary, the research conducted during this PhD program has established a robust method to analyze quiet-time SuperDARN observations. It also furthered our physical understanding of some prominent features of the mid-latitude ionosphere. It leaves behind a flexible ray-tracing model, multiple online tools to browse SuperDARN data, and a thorough and growing Space Science API providing access to multiple datasets, models and visualization tools.
Ph. D.

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Negale, Michael. "Investigating the Climatology of Mesospheric and Thermospheric Gravity Waves at High Northern Latitudes". DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/6937.

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An important property of the Earth's atmosphere is its ability to support wave motions, and indeed, waves exist throughout the Earth's atmosphere at all times and all locations. What is the importance of these waves? Imagine standing on the beach as water waves come crashing into you. In this case, the waves transport energy and momentum to you, knocking you off balance. Similarly, waves in the atmosphere crash, known as breaking, but what do they crash into? They crash into the atmosphere knocking the atmosphere off balance in terms of the winds and temperatures. Although the Earth's atmosphere is full of waves, they cannot be observed directly; however, their effects on the atmosphere can be observed. Waves can be detected in the winds and temperatures, as mentioned above, but also in pressure and density. In this dissertation, three different studies of waves, known as gravity waves, were performed at three different locations. For these studies, we investigate the size of the waves and in which direction they move. Using specialized cameras, gravity waves were observed in the middle atmosphere (50-70 miles up) over Alaska (for three winter times) and Norway (for one winter time). A third study investigated gravity waves at a much higher altitude (70 miles on up) using radar data from Alaska (for three years). These studies have provided important new information on these waves and how they move through the atmosphere. This in turn helps to understand in which direction these waves are crashing into the atmosphere and therefore, which direction the energy and momentum are going. Studies such as these help to better forecast weather and climate.

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Oronsaye, Samuel Iyen Jeffrey. "Updating the ionospheric propagation factor, M(3000)F2, global model using the neural network technique and relevant geophysical input parameters". Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001609.

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This thesis presents an update to the ionospheric propagation factor, M(3000)F2, global empirical model developed by Oyeyemi et al. (2007) (NNO). An additional aim of this research was to produce the updated model in a form that could be used within the International Reference Ionosphere (IRI) global model without adding to the complexity of the IRI. M(3000)F2 is the highest frequency at which a radio signal can be received over a distance of 3000 km after reflection in the ionosphere. The study employed the artificial neural network (ANN) technique using relevant geophysical input parameters which are known to influence the M(3000)F2 parameter. Ionosonde data from 135 ionospheric stations globally, including a number of equatorial stations, were available for this work. M(3000)F2 hourly values from 1976 to 2008, spanning all periods of low and high solar activity were used for model development and verification. A preliminary investigation was first carried out using a relatively small dataset to determine the appropriate input parameters for global M(3000)F2 parameter modelling. Inputs representing diurnal variation, seasonal variation, solar variation, modified dip latitude, longitude and latitude were found to be the optimum parameters for modelling the diurnal and seasonal variations of the M(3000)F2 parameter both on a temporal and spatial basis. The outcome of the preliminary study was applied to the overall dataset to develop a comprehensive ANN M(3000)F2 model which displays a remarkable improvement over the NNO model as well as the IRI version. The model shows 7.11% and 3.85% improvement over the NNO model as well as 13.04% and 10.05% over the IRI M(3000)F2 model, around high and low solar activity periods respectively. A comparison of the diurnal structure of the ANN and the IRI predicted values reveal that the ANN model is more effective in representing the diurnal structure of the M(3000)F2 values than the IRI M(3000)F2 model. The capability of the ANN model in reproducing the seasonal variation pattern of the M(3000)F2 values at 00h00UT, 06h00UT, 12h00UT, and l8h00UT more appropriately than the IRI version is illustrated in this work. A significant result obtained in this study is the ability of the ANN model in improving the post-sunset predicted values of the M(3000)F2 parameter which is known to be problematic to the IRI M(3000)F2 model in the low-latitude and the equatorial regions. The final M(3000)F2 model provides for an improved equatorial prediction and a simplified input space that allows for easy incorporation into the IRI model.

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Mercer, Christopher Crossley. "The search for an ionospheric model suitable for real-time applications in HF radio communications". Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1005274.

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Statement of work: In essence the research work was to focus on the development of an ionospheric model suitable for real time HF frequency prediction and direction finding applications. The modelling of the ionosphere had to be generic in nature, sufficient to ensure that the CSIR could simultaneously secure commercial competitiveness in each of the three niche market areas aforementioned, while requiring only minimal changes to software architecture in the case of each application. A little research quickly showed that the development of an ionospheric model capable of driving a HFDFSSL system in "real time" would result in one having to make only slight re-structuring of the software to facilitate application of the same model in the areas of real time frequency prediction and spectrum management. The decision made at the outset of the project to slant the research toward the development of a model best suited for HF direction finding applications is reflected in the avenues followed during the course of the modelling process

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Botai, Ondego Joel. "Ionospheric total electron content variability and its influence in radio astronomy". Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1005258.

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Ionospheric phase delays of radio signals from Global Positioning System (GPS) satellites have been used to compute ionospheric Total Electron Content (TEC). An extended Chapman profle model is used to estimate the electron density profles and TEC. The Chapman profle that can be used to predict TEC over the mid-latitudes only applies during day time. To model night time TEC variability, a polynomial function is fitted to the night time peak electron density profles derived from the online International Reference Ionosphere (IRI) 2001. The observed and predicted TEC and its variability have been used to study ionospheric in°uence on Radio Astronomy in South Africa region. Di®erential phase delays of the radio signals from Radio Astronomy sources have been simulated using TEC. Using the simulated phase delays, the azimuth and declination o®sets of the radio sources have been estimated. Results indicate that, pointing errors of the order of miliarcseconds (mas) are likely if the ionospheric phase delays are not corrected for. These delays are not uniform and vary over a broad spectrum of timescales. This implies that fast frequency (referencing) switching, closure phases and fringe ¯tting schemes for ionospheric correction in astrometry are not the best option as they do not capture the real state of the ionosphere especially if the switching time is greater than the ionospheric TEC variability. However, advantage can be taken of the GPS satellite data available at intervals of a second from the GPS receiver network in South Africa to derive parameters which could be used to correct for the ionospheric delays. Furthermore GPS data can also be used to monitor the occurrence of scintillations, (which might corrupt radio signals) especially for the proposed, Square Kilometer Array (SKA) stations closer to the equatorial belt during magnetic storms and sub-storms. A 10 minute snapshot of GPS data recorded with the Hermanus [34:420 S, 19:220 E ] dual frequency receiver on 2003-04-11 did not show the occurrence of scintillations. This time scale is however too short and cannot be representative. Longer time scales; hours, days, seasons are needed to monitor the occurrence of scintillations.

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Carozzi, Tobia. "Radio waves in the ionosphere : Propagation, generation and detection". Doctoral thesis, Uppsala universitet, Institutionen för astronomi och rymdfysik, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1184.

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We discuss various topics concerning the propagation, generation, and detec-tionof high-frequency (HF) radio waves in the Earth's ionosphere. With re-gardsto propagation, we derive a full wave Hamiltonian and a polarization evo-lutionequation for electromagnetic waves in a cold, stratified magnetoplasma.With regards to generation, we will be concerned with three experiments con-ducted at the ionosphere- radio wave interaction research facilities at Sura, Rus-siaand Tromsø, Norway. These facilities operate high power HF transmittersthat can inject large amplitude electromagnetic waves into the ionosphere andexcite numerous nonlinear processes. In an experiment conducted at the Surafacility, we were able to measure the full state of polarization of stimulatedelectromagnetic emissions for the first time. It is expected that by using thetechnique developed in this experiment it will be possible to study nonlinearpolarization effects on powerful HF pump waves in magnetoplasmas in the fu-ture.In another experiment conducted at the Sura facility, the pump frequencywas swept automatically allowing rapid, high-resolution measurements of SEEdependence on pump frequency with minimal variations in ionospheric condi-tions.At the Tromsø facility we discovered by chance a highly variable, pumpinduced, HF emission that most probably emanated from pump excited spo-radicE. Regarding detection, we have proposed a set of Stokes parametersgeneralized to three dimension space; and we have used these parameters in aninvention to detect the incoming direction of electromagnetic waves of multiplefrequencies from a single point measurement.

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Carozzi, Tobia D. "Radio waves in the ionosphere : propagation, generation, and detection /". Uppsala : Institutionen för astronomi och rymdfysik, Univ. [distributör], 2000. http://publications.uu.se/theses/99-3364278-2/.

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Habarulema, John Bosco. "A contribution to TEC modelling over Southern Africa using GPS data". Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1005241.

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Modelling ionospheric total electron content (TEC) is an important area of interest for radio wave propagation, geodesy, surveying, the understanding of space weather dynamics and error correction in relation to Global Navigation Satellite Systems (GNNS) applications. With the utilisation of improved ionosonde technology coupled with the use of GNSS, the response of technological systems due to changes in the ionosphere during both quiet and disturbed conditions can be historically inferred. TEC values are usually derived from GNSS measurements using mathematically intensive algorithms. However, the techniques used to estimate these TEC values depend heavily on the availability of near-real time GNSS data, and therefore, are sometimes unable to generate complete datasets. This thesis investigated possibilities for the modelling of TEC values derived from the South African Global Positioning System (GPS)receiver network using linear regression methods and artificial neural networks (NNs). GPS TEC values were derived using the Adjusted Spherical Harmonic Analysis (ASHA) algorithm. Considering TEC and the factors that influence its variability as “dependent and independent variables” respectively, the capabilities of linear regression methods and NNs for TEC modelling were first investigated using a small dataset from two GPS receiver stations. NN and regression models were separately developed and used to reproduce TEC fluctuations at different stations not included in the models’ development. For this purpose, TEC was modelled as a function of diurnal variation, seasonal variation, solar and magnetic activities. Comparative analysis showed that NN models provide predictions of GPS TEC that were an improvement on those predicted by the regression models developed. A separate study to empirically investigate the effects of solar wind on GPS TEC was carried out. Quantitative results indicated that solar wind does not have a significant influence on TEC variability. The final TEC simulation model developed makes use of the NN technique to find the relationship between historical TEC data variations and factors that are known to influence TEC variability (such as solar and magnetic activities, diurnal and seasonal variations and the geographical locations of the respective GPS stations) for the purposes of regional TEC modelling and mapping. The NN technique in conjunction with interpolation and extrapolation methods makes it possible to construct ionospheric TEC maps and to analyse the spatial and temporal TEC behaviour over Southern Africa. For independent validation, modelled TEC values were compared to ionosonde TEC and the International Reference Ionosphere (IRI) generated TEC values during both quiet and disturbed conditions. This thesis provides a comprehensive guide on the development of TEC models for predicting ionospheric variability over the South African region, and forms a significant contribution to ionospheric modelling efforts in Africa.

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Książki na temat "Ionospheic wave propagation"

A, Zherebt͡s︡ov G., Tashchilin A. V i Sibirskiĭ institut zemnogo magnetizma ionosfery i rasprostranenii͡a︡ radiovoln., red. Fizika ionosfery i rasprostranenii͡a︡ radiovoln: Sbornik nauchnykh trudov. Moskva: Nauka, 1989.

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McNamara, L. F. The ionosphere: Communications, surveillance, and direction finding. Malabar, Fla: Krieger Pub. Co., 1991.

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A, Zherebt͡s︡ov G., i Sibirskiĭ institut zemnogo magnetizma, ionosfery i rasprostranenii͡a︡ radiovoln., red. Fizika ionosfery i rasprostranenii͡a︡ radiovoln: Sbornik nauchnykh trudov. Moskva: "Nauka", 1988.

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G, Gelʹberg M., Institut Kosmofizicheskikh issledovaniĭ i aėronomii (Akademii͡a︡ nauk SSSR) i Soveshchanie po probleme "Neodnorodnai͡a︡ struktura ionosfery" (7th : 1991? : I͡A︡kutsk, Russia?), red. Neodnorodnai͡a︡ struktura ionosfery: Sbornik nauchnykh trudov. I͡A︡kutsk: I͡A︡kutskiĭ nauch. t͡s︡entr SO AN SSSR, 1991.

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Pavlovna, Benʹkova Natalʹi͡a, red. Ionosfera Zemli. Moskva: Izd-vo "Nauka", 1985.

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Laboratory), Ionospheric Effects Symposium (6th 1990 Naval Research. The effect of the ionosphere on radiowave signals and system performance: Based on Ionospheric Effects Symposium, 1-3 May 1990. [Washington, DC: U.S. G.P.O., 1990.

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D, Borisov N., Moiseev B. S i Institut zemnogo magnetizma, ionosfery i rasprostranenii͡a︡ radiovoln (Akademii͡a︡ nauk SSSR), red. Issledovanie struktury i volnovykh svoĭstv prizemnoĭ plazmy. Moskva: In-t zemnogo magnetizma, ionosfery i rasprostranenii͡a︡ radiovoln AN SSSR, 1989.

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M, Goodman John, i Naval Research Laboratory (U.S.), red. The effect of the ionosphere on communication, navigation, and surveillance systems: Based on Ionospheric Effects Symposium, 5-7 May 1987. [Washington, DC: Naval Research Laboratory], 1988.

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Karlovich, Sloka Viktor, i Radiotekhnicheskiĭ institut (Akademii͡a︡ nauk SSSR), red. Radiotekhnicheskie voprosy issledovanii͡a︡ ionosfery: Sbornik nauchnykh trudov. Moskva: Akademii͡a︡ nauk SSSR, Radiotekhn. in-t, 1985.

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Evgenʹevich, Stepanov Vladimir, red. Fizika ionosfery i rasprostranenii͡a︡ radiovoln. Moskva: "Nauka", 1985.

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Części książek na temat "Ionospheic wave propagation"

Rawer, Karl. "Propagation through the ionosphere". W Wave Propagation in the Ionosphere, 139–58. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_10.

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Rawer, Karl. "Introduction". W Wave Propagation in the Ionosphere, 3–5. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_1.

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Rawer, Karl. "The real ionosphere: Irregularities and acoustic-gravity waves". W Wave Propagation in the Ionosphere, 159–90. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_11.

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Rawer, Karl. "Propagation in structured media". W Wave Propagation in the Ionosphere, 191–219. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_12.

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Rawer, Karl. "Collisional attenuation". W Wave Propagation in the Ionosphere, 225–43. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_13.

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Rawer, Karl. "Kinetic theory of a Lorentz plasma". W Wave Propagation in the Ionosphere, 245–55. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_14.

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Rawer, Karl. "The Boltzmann equation of a compressible plasma". W Wave Propagation in the Ionosphere, 257–72. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_15.

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Rawer, Karl. "Waves in a warm isotropic plasma". W Wave Propagation in the Ionosphere, 273–80. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_16.

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Rawer, Karl. "Wave in a warm gyrotropic plasma". W Wave Propagation in the Ionosphere, 281–91. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_17.

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Rawer, Karl. "Plasma waves". W Wave Propagation in the Ionosphere, 293–304. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3665-7_18.

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Streszczenia konferencji na temat "Ionospheic wave propagation"

Bakhmet'eva, Natalia, Valery Vyakhirev, Elena Kalinina, Ilya Zhemyakov i Grigory Vinogradov. "Vertical Motions in the Lower Ionosphere and Dynamics of the Ionospheric Plasma". W 2019 Russian Open Conference on Radio Wave Propagation (RWP). IEEE, 2019. http://dx.doi.org/10.1109/rwp.2019.8810386.

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Dighe, Kalpak A., Craig A. Tepley, Raul Garcia i Jonathan Friedman. "The Arecibo Observatory Daytime Lidar : Preliminary Results". W Optical Remote Sensing of the Atmosphere. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/orsa.1993.tud.15.

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The vertical propagation of atmospheric tides and acoustic gravity waves and their corresponding travelling ionospheric disturbances play a crucial role in the transportation and balance of momentum and energy in the earth's atmosphere. The unique availability of both radar and lidar instrumentation at Arecibo can provide simultaneous access to the neutral density, temperature and wind perturbations induced by such wave activity at mesospheric and stratospheric altitudes.

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"Radiowave propagation in ionosphere". W 2017 Radiation and Scattering of Electromagnetic Waves (RSEMW). IEEE, 2017. http://dx.doi.org/10.1109/rsemw.2017.8103577.

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Deminov, Marat G., i Rafael G. Deminov. "Geomagnetic Index for Intense Ionospheric Storm". W 2019 Russian Open Conference on Radio Wave Propagation (RWP). IEEE, 2019. http://dx.doi.org/10.1109/rwp.2019.8810384.

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Maltseva, O. A., N. S. Mozhaeva, T. V. Nikitenko i T. T. Quang. "HF radio wave propagation in conditions of prolonged low solar activity". W 12th IET International Conference on Ionospheric Radio Systems and Techniques (IRST 2012). IET, 2012. http://dx.doi.org/10.1049/cp.2012.0402.

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Guo, Qiang, Leonid F. Chernogor, Konstantin P. Garmash, Yiyang Luo, Victor T. Rozumenko i Yu Zheng. "Ionospheric Disturbances and Their Impacts on HF Radio Wave Propagation". W 2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS). IEEE, 2021. http://dx.doi.org/10.23919/ursigass51995.2021.9560548.

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Repin, Andrey, Mikhail Anishin, Boris Barabashov, Dmitry Demin, Valentina Denisova, Sergey Zhuravlev, Nadezhda Kotonayeva i Konstantin Tsybulya. "The Long- and Short-Term Ionospheric Forecast Service for the Shortwave Propagation". W 2019 Russian Open Conference on Radio Wave Propagation (RWP). IEEE, 2019. http://dx.doi.org/10.1109/rwp.2019.8810196.

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Martin-Hidalgo, Julio, Charles M. Swenson i Daniel Farr. "RaPTIR: Radio-wave propagation through ionosphere regions CubeSat mission". W 2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM). IEEE, 2014. http://dx.doi.org/10.1109/usnc-ursi-nrsm.2014.6928030.

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Tinin, M. V., i S. I. Knizhin. "On radio wave propagation in multiscale randomly inhomogeneous ionosphere". W 2017 Progress In Electromagnetics Research Symposium - Spring (PIERS). IEEE, 2017. http://dx.doi.org/10.1109/piers.2017.8261946.

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Yu.A, Polevoda, S. V. Litvinov, R. V. Gorbunov i Saleev V.Yu. "Radio wave propagation in radio occultation of the ionosphere". W 2022 IEEE 8th All-Russian Microwave Conference (RMC). IEEE, 2022. http://dx.doi.org/10.1109/rmc55984.2022.10079616.

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Raporty organizacyjne na temat "Ionospheic wave propagation"

Kintner, Paul M. Studies of Electrostatic Waves, VLF-wave Particle Interactions, and Propagations in the Ionosphere. Fort Belvoir, VA: Defense Technical Information Center, wrzesień 1997. http://dx.doi.org/10.21236/ada628007.

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Murphy, T. Propagation of electromagnetic waves in a structured ionosphere. Office of Scientific and Technical Information (OSTI), czerwiec 1996. http://dx.doi.org/10.2172/285449.

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