Journal articles on the topic 'Ionosphere'
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1
Kliore, A. J. "Satellite Atmospheres and Magnetospheres." Highlights of Astronomy 11, no. 2 (1998): 1065–69. http://dx.doi.org/10.1017/s1539299600019602.
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AbstractGalileo radio-occultation measurements show that all four of the Galilean satellites possess ionospheres. Peak ionospheric densities for the icy satellites are several thousand electrons per cubic centimeter, and the distributions are not spherically symmetric. Io’s ionosphere is much denser and remarkably similar to that measured by Voyager.
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Rao, N. D. Parameswara, E. Sneha Priya, Sk Haneef, K. Sowmya, U. Abhishek Chowdary, and U. Sushmita. "ThingSpeak an IOT Application and Analytics System for GNSS with MATLAB Analysis." International Journal of Innovative Research in Engineering and Management 10, no. 3 (June 27, 2023): 189–92. http://dx.doi.org/10.55524/ijirem.2023.10.3.28.
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The ionosphere is an essential component of the Global Navigation Satellite System (GNSS) that can affect the accuracy and dependability of GNSS location. MATLAB provides comprehensive tools for the analysis of ionospheric data and its impact on GNSS positioning. To examine the ionospheric data utilized in GNSS positioning, we advise utilizing MATLAB in this application. The analysis is based on a determination of the Total Electron Content (TEC) of the ionosphere in order to account for the ionospheric delay in the GNSS signals. The system consists of a GNSS receiver module connected to a microcontroller with Wi-Fi capabilities, which transmits data to Matlab. The data is processed in Matlab before being used there. Then, in order to account for the ionospheric delay in the GNSS signals, the TEC of the ionosphere is calculated using Matlab. The recommended system provides a scalable and flexible environment for GNSS-based ionospheric data analysis. The system is practical for a range of applications, including surveying, geodesy, and navigation, and it may be readily adapted to fulfill specific customer requirements.For Matlab analysis, the approach has a number of advantages. In order to measure the TEC of the ionosphere precisely, it first provides cutting-edge signal processing technologies. Additionally, it makes it possible to display ionospheric data in a number of different ways, such as maps, graphs, and time-series plots. This can be applied to the data to identify patterns and trends. The proposed MATLAB-based system offers a scalable, flexible, and cutting-edge platform for the estimation of the ionosphere's TEC and the correction of the ionospheric delay in the GNSS signals.
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Prajapati, Parinda, and Nimisha Patel. "Ionospheric Model Development for Indian Region: A Survey Paper." ECS Transactions 107, no. 1 (April 24, 2022): 11075–82. http://dx.doi.org/10.1149/10701.11075ecst.
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Ionosphere’s role is most important in vigorous satellite communication for the navigation positional correctness purpose. Ionosphere contains diverse layers reliant on its electron density with altitude in the layer. There are various ionospheric models to forecast electron density with temporal resolutions cited by literatures. GPS data is frequently used by these models. So, the necessity is a prerequisite of evolving ionospheric models with different time duration for low latitudes of India. Also, an ionosphere tomography is considered as an ill-posed problem. Ionospheric TEC found simultaneously at numerous locations can be preserved with several algorithms to conquer electron density. This research is proposed for evolving a model to forecast 3D tomography of total electron density for the whole Indian region. Mainly used satellite data can be collected by various means. The management of vast statistics are planned by using data mining techniques and artificial neural network techniques for estimation. This paper is an outcome of detailed research on ionospheric model development.
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Saka, Osuke. "Ionospheric control of space weather." Annales Geophysicae 39, no. 3 (May 17, 2021): 455–60. http://dx.doi.org/10.5194/angeo-39-455-2021.
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Abstract. As proposed by Saka (2019), plasma injections arising out of the auroral ionosphere (ionospheric injection) are a characteristic process of the polar ionosphere at substorm onset. The ionospheric injection is triggered by westward electric fields transmitted from the convection surge in the magnetosphere at field line dipolarization. Localized westward electric fields result in local accumulation of ionospheric electrons and ions, which produce local electrostatic potentials in the auroral ionosphere. Field-aligned electric fields are developed to extract excess charges from the ionosphere. This process is essential to the equipotential equilibrium of the auroral ionosphere. Cold electrons and ions that evaporate from the auroral ionosphere by ionospheric injection tend to generate electrostatic parallel potential below an altitude of 10 000 km. This is a result of charge separation along the mirror fields introduced by the evaporated electrons and ions moving earthward in phase space.
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Farah, Ashraf. "Single-Frequency Ionospheric-Delay Correction from BeiDou & GPS Systems for Northern Hemisphere." Artificial Satellites 54, no. 1 (March 1, 2019): 1–15. http://dx.doi.org/10.2478/arsa-2019-0002.
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Abstract The range delay caused by the ionosphere layer is the major current source of error for GNSS users with single-frequency receivers. GNSS advice users to correct this type of error using ionospheric models whose coefficients are sent in their navigation messages. GPS-users use the Klobuchar model to correct this type of error. GPS navigation message contains the model’s eight coefficients which vary on the basis of seasonal ionospheric variations and average solar flux. The correction accuracy of Klobuchar model is about 50% (rms) of the ionospheric range delay. Beidou system calculates and broadcast 8 parameters of Klobuchar model based on continuous monitoring stations. BeiDou system updates the ionospheric coefficients every two hours. GPS-Klobuchar model uses completely different coefficients than BeiDou-Klobuchar model. This research demonstrates a comparison study between the Klobuchar model using the GPS broadcast coefficients and the same model using BeiDou-coefficients. The correction accuracy offered by the two models has been judged using the most accurate International GNSS Service-Global Ionospheric Maps (IGS-GIMs) for three different-latitude stations along northern hemisphere, one station in low-latitude region, the second station is in mid-latitude region and the third station is in high-latiude region to reflect models’ behaviour in different geographic regions. The study was applied over three different months of the year 2017 that each of them reflects a different activity state for the ionosphere layer. The study proves that BeiDou model is able to show the ionosphere’s day-to-day fluctuations while GPS model can’t. It can be concluded that GPS model offers better behaviour than BeiDou model in correcting range delay in low-latitude and high-latitude geographic regions under any activity state for the ionosphere. BeiDou model offers better correction accuracy than GPS model in mid-latitude under any activity state for the ionosphere.
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Karpachev, Alexander. "Advanced Classification of Ionospheric Troughs in the Morning and Evening Conditions." Remote Sensing 14, no. 16 (August 20, 2022): 4072. http://dx.doi.org/10.3390/rs14164072.
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The separation and classification of ionospheric troughs in the winter evening and morning ionospheres of the southern hemisphere were performed using CHAMP satellite data for high solar activity (2000–2002). In the high-latitude ionosphere, the main ionospheric trough (MIT) was separated from the high-latitude trough (HLT). The separation was carried out using a thorough analysis of all the characteristic structures of the ionosphere in the framework of the auroral diffuse particle precipitation model. Two types of high-latitude troughs were identified: (1) a wide trough associated with zone II of diffuse precipitation on the poleward edge of the auroral oval and (2) a narrow trough of ionization, which is presumably associated with an electric field action. The poleward wall of MIT is as ever formed by diffuse precipitation in zone I on the equatorward edge of the auroral oval. The HLT and MIT separation is most difficult at the longitudes of the eastern hemisphere, where all structures are located at the highest latitudes and partially overlap. In the mid-latitude ionosphere, all the characteristic structures of the ionosphere were also identified and considered. MIT was separated from the ring ionospheric trough (RIT), which is formed by the decay processes of the magnetospheric ring current. The separation of MIT and RIT was performed based on an analysis of the prehistory of all geomagnetic disturbances during the period under study. In addition to the RIT, a decrease in the electron density equatorward of the MIT was found to be often formed at the America–Atlantic longitudes, which masks the MIT minimum. For completeness, all cases of a clearly defined polar cavity are also presented.
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Elsayed, Ahmed, Ahmed Sedeek, Mohamed Doma, and Mostafa Rabah. "Vertical ionospheric delay estimation for single-receiver operation." Journal of Applied Geodesy 13, no. 2 (April 26, 2019): 81–91. http://dx.doi.org/10.1515/jag-2018-0041.
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Abstract An apparent delay is occurred in GPS signal due to both refraction and diffraction caused by the atmosphere. The second region of the atmosphere is the ionosphere. The ionosphere is significantly related to GPS and the refraction it causes in GPS signal is considered one of the main source of errors which must be eliminated to determine accurate positions. GPS receiver networks have been used for monitoring the ionosphere for a long time. The ionospheric delay is the most predominant of all the error sources. This delay is a function of the total electron content (TEC). Because of the dispersive nature of the ionosphere, one can estimate the ionospheric delay using the dual frequency GPS. In the current research our primary goal is applying Precise Point Positioning (PPP) observation for accurate ionosphere error modeling, by estimating Ionosphere delay using carrier phase observations from dual frequency GPS receiver. The proposed algorithm was written using MATLAB and was named VIDE program. The proposed Algorithm depends on the geometry-free carrier-phase observations after detecting cycle slip to estimates the ionospheric delay using a spherical ionospheric shell model, in which the vertical delays are described by means of a zenith delay at the station position and latitudinal and longitudinal gradients. Geometry-free carrier-phase observations were applied to avoid unwanted effects of pseudorange measurements, such as code multipath. The ionospheric estimation in this algorithm is performed by means of sequential least-squares adjustment. Finally, an adaptable user interface MATLAB software are capable of estimating ionosphere delay, ambiguity term and ionosphere gradient accurately.
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Danzer, J., S. B. Healy, and I. D. Culverwell. "A simulation study with a new residual ionospheric error model for GPS radio occultation climatologies." Atmospheric Measurement Techniques 8, no. 8 (August 21, 2015): 3395–404. http://dx.doi.org/10.5194/amt-8-3395-2015.
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Abstract. In this study, a new model was explored which corrects for higher order ionospheric residuals in Global Positioning System (GPS) radio occultation (RO) data. Recently, the theoretical basis of this new "residual ionospheric error model" has been outlined (Healy and Culverwell, 2015). The method was tested in simulations with a one-dimensional model ionosphere. The proposed new model for computing the residual ionospheric error is the product of two factors, one of which expresses its variation from profile to profile and from time to time in terms of measurable quantities (the L1 and L2 bending angles), while the other describes the weak variation with altitude. A simple integral expression for the residual error (Vorob’ev and Krasil’nikova, 1994) has been shown to be in excellent numerical agreement with the exact value, for a simple Chapman layer ionosphere. In this case, the "altitudinal" element of the residual error varies (decreases) by no more than about 25 % between ~10 and ~100 km for physically reasonable Chapman layer parameters. For other simple model ionospheres the integral can be evaluated exactly, and results are in reasonable agreement with those of an equivalent Chapman layer. In this follow-up study the overall objective was to explore the validity of the new residual ionospheric error model for more detailed simulations, based on modeling through a complex three-dimensional ionosphere. The simulation study was set up, simulating day and night GPS RO profiles for the period of a solar cycle with and without an ionosphere. The residual ionospheric error was studied, the new error model was tested, and temporal and spatial variations of the model were investigated. The model performed well in the simulation study, capturing the temporal variability of the ionospheric residual. Although it was not possible, due to high noise of the simulated bending-angle profiles at mid- to high latitudes, to perform a thorough latitudinal investigation of the performance of the model, first positive and encouraging results were found at low latitudes. Furthermore, first application tests of the model on the data showed a reduction in temperature level of the ionospheric residual at 40 km from about −2.2 to −0.2 K.
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Danzer, J., S. B. Healy, and I. D. Culverwell. "A simulation study with a new residual ionospheric error model for GPS radio occultation climatologies." Atmospheric Measurement Techniques Discussions 8, no. 1 (January 27, 2015): 1151–76. http://dx.doi.org/10.5194/amtd-8-1151-2015.
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Abstract. In this study, a new model was explored, which corrects for higher order ionospheric residuals in global positioning system (GPS) radio occultation (RO) data. Recently, the theoretical basis of this new "residual ionospheric error model" has been outlined (Healy and Culverwell, 2015). The method was tested in simulations with a one-dimensional model ionosphere. The proposed new model for computing the residual ionospheric error is the product of two factors, one of which expresses its variation from profile-to-profile and from time-to-time in terms of measurable quantities (the L1 and L2 bending angles), the other of which describes the weak variation with altitude. A simple integral expression for the residual error (Vorob’ev and Krasil’nikova, 1994) has been shown to be in excellent numerical agreement with the exact value, for a simple Chapman layer ionosphere. In this case, the "altitudinal" element of the residual error varies (decreases) by no more than about 25% between ~10 and ~100 km for physically reasonable Chapman layer parameters. For other simple model ionospheres the integral can be evaluated exactly, and results are in reasonable agreement with those of an equivalent Chapman layer. In this follow-up study the overall objective was to explore the validity of the new residual ionospheric error model for more detailed simulations, based on modelling through a complex three-dimensional ionosphere. The simulation study was set up, simulating day and night GPS RO profiles for the period of a solar cycle with and without an ionosphere. The residual ionospheric error was studied, the new error model was tested, and temporal and spatial variations of the model were investigated. The model performed well in the simulation study, capturing the temporal variability of the ionospheric residual. Although, it was not possible, due to high noise of the simulated bending angle profiles at mid to high latitudes, to perform a thorough latitudinal investigation of the performance of the model, first positive and encouraging results were found at low latitudes. Furthermore, first application tests of the model on the data showed a reduction on temperature level of the ionospheric residual at 40 km from about −2.2 to −0.2 K.
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Janhunen, P. "On the possibility of using an electromagnetic ionosphere in global MHD simulations." Annales Geophysicae 16, no. 4 (April 30, 1998): 397–402. http://dx.doi.org/10.1007/s00585-998-0397-y.
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Abstract. Global magnetohydrodynamic (MHD) simulations of the Earth's magnetosphere must be coupled with a dynamical ionospheric module in order to give realistic results. The usual approach is to compute the field-aligned current (FAC) from the magnetospheric MHD variables at the ionospheric boundary. The ionospheric potential is solved from an elliptic equation using the FAC as a source term. The plasma velocity at the boundary is the E × B velocity associated with the ionospheric potential. Contemporary global MHD simulations which include a serious ionospheric model use this method, which we call the electrostatic approach in this paper. We study the possibility of reversing the flow of information through the ionosphere: the magnetosphere gives the electric field to the ionosphere. The field is not necessarily electrostatic, thus we will call this scheme electromagnetic. The electric field determines the horizontal ionospheric current. The divergence of the horizontal current gives the FAC, which is used as a boundary condition for MHD equations. We derive the necessary formulas and discuss the validity of the approximations necessarily involved. It is concluded that the electromagnetic ionosphere-magnetosphere coupling scheme is a serious candidate for future global MHD simulators, although a few problem areas still remain. At minimum, it should be investigated further to discover whether there are any differences in the simulation using the electrostatic or the electromagnetic ionospheric coupling.Key words. Ionosphere · Ionosphere-magnetosphere interaction · Magnetospheric physics · Magnetosphere-ionosphere interaction · Space plasma physics · Numerical simulation studies
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Hayes, Laura A., and Peter T. Gallagher. "A Significant Sudden Ionospheric Disturbance Associated with Gamma-Ray Burst GRB 221009A." Research Notes of the AAS 6, no. 10 (October 26, 2022): 222. http://dx.doi.org/10.3847/2515-5172/ac9d2f.
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Abstract We report the detection of a significant sudden ionospheric disturbance in the D-region of Earth’s ionosphere (∼60–100 km), which was associated with the massive γ-ray burst GRB 221009A that occurred on 2022 October 9. We identified the disturbance over northern Europe—a result of the increased ionization by X- and γ-ray emission from the GRB-using very low frequency radio waves as a probe of the D-region. These observations demonstrate that an extra-galactic GRB (z ∼ 0.151) can have a significant impact on the terrestrial atmosphere and illustrates that the Earth’s ionosphere can be used as a giant X- and γ-ray detector. Indeed, these observations may provide an insight into the impacts of GRBs on the ionospheres of planets in our solar system and beyond.
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Parker, James A. D., S. Eleri Pryse, Natasha Jackson-Booth, and Rachel A. Buckland. "Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC." Annales Geophysicae 36, no. 1 (January 25, 2018): 125–38. http://dx.doi.org/10.5194/angeo-36-125-2018.
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Abstract. The main ionospheric trough is a large-scale spatial depletion in the electron density distribution at the interface between the high- and mid-latitude ionosphere. In western Europe it appears in early evening, progresses equatorward during the night, and retreats rapidly poleward at dawn. It exhibits substantial day-to-day variability and under conditions of increased geomagnetic activity it moves progressively to lower latitudes. Steep gradients on the trough-walls on either side of the trough minimum, and their variability, can cause problems for radio applications. Numerous studies have sought to characterize and quantify the trough behaviour. The Electron Density Assimilative Model (EDAM) models the ionosphere on a global scale. It assimilates observations into a background ionosphere, the International Reference Ionosphere 2007 (IRI2007), to provide a full 3-D representation of the ionospheric plasma distribution at specified times and days. This current investigation studied the capability of EDAM to model the ionosphere in the region of the main trough. Total electron content (TEC) measurements from 46 GPS stations in western Europe from September to December 2002 were assimilated into EDAM to provide a model of the ionosphere in the trough region. Vertical electron content profiles through the model revealed the trough and the detail of its structure. Statistical results are presented of the latitude of the trough minimum, TEC at the minimum and of other defined parameters that characterize the trough structure. The results are compared with previous observations made with the Navy Ionospheric Monitoring System (NIMS), and reveal the potential of EDAM to model the large-scale structure of the ionosphere. Keywords. Ionosphere (midlatitude ionosphere; modelling and forecasting) – radio science (ionospheric physics)
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Романова, Елена, Elena Romanova, Галина Котович, Galina Kotovich, Сергей Пономарчук, Sergey Ponomarchuk, Антон Ким, and Anton Kim. "Modeling z-shaped disturbance along the Pedersen ray of oblique sounding ionogram using adaptation of IRI to experimental data." Solnechno-Zemnaya Fizika 2, no. 4 (December 20, 2016): 43–53. http://dx.doi.org/10.12737/21815.
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We present the results of numerical modeling of a traveling ionospheric disturbance that causes z-shaped bends at the Pedersen ray of oblique incidence ionograms. The results of trajectory synthesis of oblique incidence ionograms are given for the ionosphere, taking into account the traveling ionospheric disturbance. In the work, we use the International Reference Ionosphere, adapted to experimental data, and the Model of Ionosphere and Plasmasphere.
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Chisham, G., M. Pinnock, A. S. Rodger, and J. P. Villain. "High-time resolution conjugate SuperDARN radar observations of the dayside convection response to changes in IMF B<sub>y</sub>." Annales Geophysicae 18, no. 2 (February 29, 2000): 191–201. http://dx.doi.org/10.1007/s00585-000-0191-y.
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Abstract. We present data from conjugate SuperDARN radars describing the high-latitude ionosphere's response to changes in the direction of IMF By during a period of steady IMF Bz southward and Bx positive. During this interval, the radars were operating in a special mode which gave high-time resolution data (30 s sampling period) on three adjacent beams with a full scan every 3 min. The location of the radars around magnetic local noon at the time of the event allowed detailed observations of the variations in the ionospheric convection patterns close to the cusp region as IMF By varied. A significant time delay was observed in the ionospheric response to the IMF By changes between the two hemispheres. This is explained as being partially a consequence of the location of the dominant merging region on the magnetopause, which is ~8-12RE closer to the northern ionosphere than to the southern ionosphere (along the magnetic field line) due to the dipole tilt of the magnetosphere and the orientation of the IMF. This interpretation supports the anti-parallel merging hypothesis and highlights the importance of the IMF Bx component in solar wind-magnetosphere coupling.Key words: Ionosphere (plasma convection) - Magnetospheric physics (magnetopause, cusp, and boundary layers; solar wind - magnetosphere interactions)
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Chen, Zhou, Bokun An, Wenti Liao, Yungang Wang, Rongxin Tang, Jingsong Wang, and Xiaohua Deng. "Ionospheric Electron Density Model by Electron Density Grid Deep Neural Network (EDG-DNN)." Atmosphere 14, no. 5 (April 29, 2023): 810. http://dx.doi.org/10.3390/atmos14050810.
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Electron density (or electron concentration) is a critical metric for characterizing the ionosphere’s mobility. Shortwave technologies, remote sensing systems, and satellite communications—all rely on precise estimations of electron density in the ionosphere. Using electron density profiles from FORMOSAT-3/COSMIC (Constellation Observation System for Meteorology, Ionosphere, and Climate) from 2006 to 2013, a four-dimensional physical grid model of ionospheric electron density was created in this study. The model, known as EDG-DNN, utilizes a DNN (deep neural network), and its output is the electron density displayed as a physical grid. The preprocessed electron density data are used to construct training, validation, and test sets. The International Reference Ionosphere model (IRI) was chosen as the reference model for the validation procedure since it predicts electron density well. This work used the IRI-2016 version. IRI-2016 produced more precise results of electron density when time and location parameters were input. This study compares the electron density provided by IRI-2016 to the EDG-DNN to assess the merits of the latter. The final results reveal that EDG-DNN has low-error and strong stability, can represent the global distribution structure of electron density, has some distinctive features of ionospheric electron density distribution, and predicts electron density well during quiet periods.
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Sassi, Fabrizio, Angeline G. Burrell, Sarah E. McDonald, Jennifer L. Tate, and John P. McCormack. "On the importance of middle-atmosphere observations on ionospheric dynamics using WACCM-X and SAMI3." Annales Geophysicae 42, no. 1 (June 10, 2024): 255–69. http://dx.doi.org/10.5194/angeo-42-255-2024.
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Abstract. Recent advances in atmospheric observations and modeling have enabled the investigation of thermosphere–ionosphere interactions as a whole-atmosphere problem. This study examines how dynamical variability in the middle atmosphere (MA) affects intra-day changes in the thermosphere and ionosphere. Specifically, this study investigates ionosphere–thermosphere interactions during different time periods of January 2013 using the Specified Dynamics Whole Atmosphere Community Climate Model, eXtended version (SD-WACCM-X), coupled to the Naval Research Laboratory (NRL) ionosphere of the Sami3 is Another Model of the Ionosphere (SAMI3) model. To represent the weather of the day, the coupled thermosphere–ionosphere system is nudged below 90 km toward the atmospheric specifications provided by the Navy Global Environmental Model for High-Altitude (NAVGEM-HA). Hindcast simulations during January 2013 are carried out with the full dataset of observations normally assimilated by NAVGEM-HA and with a degraded dataset where observations above 40 km are not assimilated. Ionospheric regions with statistically significant changes are identified using key ionospheric properties, including the electron density, peak electron density, and height of the peak electron density. Ionospheric changes show a spatial structure that illustrates the impact of two different types of coupling between the thermosphere and the ionosphere: variability induced by wind-dynamo coupling through electric conductivity and ion-neutral interactions in the upper thermosphere. The two simulations presented in this study show that changing the state of the MA affects ionosphere–thermosphere coupling through changes in the behavior and amplitude of non-migrating tides, resulting in improved key ionospheric specifications.
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Peng, YuXiang, and Wayne A. Scales. "Ionospheric Remote Sensing with GNSS." Encyclopedia 1, no. 4 (November 22, 2021): 1246–56. http://dx.doi.org/10.3390/encyclopedia1040094.
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The Global Navigation Satellite System (GNSS) plays a pivotal role in our modern positioning, navigation and timing (PNT) technologies. GNSS satellites fly at altitudes of approximately 20,000 km or higher. This altitude is above an ionized layer of the Earth’s upper atmosphere, the so called “ionosphere”. Before reaching a typical GNSS receiver on the ground, GNSS satellite signals penetrate through the Earth’s ionosphere. The ionosphere is a plasma medium consisting of free charged particles that can slow down, attenuate, refract, or scatter the GNSS signals. Ionospheric density structures (also known as irregularities) can cause GNSS signal scintillations (phase and intensity fluctuations). These ionospheric impacts on GNSS signals can be utilized to observe and study physical processes in the ionosphere and is referred to ionospheric remote sensing. This entry introduces some fundamentals of ionospheric remote sensing using GNSS.
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Ким, Антон, Anton Kim, Елена Романова, Elena Romanova, Галина Котович, Galina Kotovich, Сергей Пономарчук, and Sergey Ponomarchuk. "Modeling z-shaped disturbance along the Pedersen ray of oblique sounding ionogram using adaptation of IRI to experimental data." Solar-Terrestrial Physics 2, no. 4 (February 2, 2017): 55–69. http://dx.doi.org/10.12737/24273.
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We present the results of numerical modeling of a traveling ionospheric disturbance that causes z-shaped bends at the Pedersen ray of oblique incidence ionograms. The results of trajectory synthesis of oblique incidence ionograms are given for the ionosphere, taking into account the traveling ionospheric disturbance. In the work, we use the International Reference Ionosphere, adapted to experimental data, and the Global Model of the Ionosphere and Plasmasphere.
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An, Xiangdong, Xiaolin Meng, Hua Chen, Weiping Jiang, Ruijie Xi, and Qusen Chen. "Modelling Global Ionosphere Based on Multi-Frequency, Multi-Constellation GNSS Observations and IRI Model." Remote Sensing 12, no. 3 (January 31, 2020): 439. http://dx.doi.org/10.3390/rs12030439.
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With the emergence of BeiDou and Galileo as well as the modernization of GPS and GLONASS, more available satellites and signals enhance the capability of Global Navigation Satellite Systems (GNSS) to monitor the ionosphere. However, currently the International GNSS Service (IGS) Ionosphere Associate Analysis Centers (IAACs) just use GPS and GLONASS dual-frequency observations in ionosphere estimation. To better determine the global ionosphere, we used multi-frequency, multi-constellation GNSS observations and a priori International Reference Ionosphere (IRI) to model the ionosphere. The newly estimated ionosphere was represented by a spherical harmonic expansion function with degree and order of 15 in a solar-geomagnetic frame. By collecting more than 300 stations with a global distribution, we processed and analysed two years of data. The estimated ionospheric results were compared with those of IAACs, and the averaged Root Mean Squares (RMS) of Total Electron Content (TEC) differences for different solutions did not exceed 3 TEC Unit (TECU). Through validation by satellite altimetry, it was suggested that the newly established ionosphere had a higher precision than the IGS products. Moreover, compared with IGS ionospheric products, the newly established ionosphere showed a more accurate response to the ionosphere disturbances during the geomagnetic storms.
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El Manaily, Emad, Mahmoud Abd Rabbou, Adel El-Shazly, and Moustafa Baraka. "Enhanced Local Ionosphere Model for Multi-Constellations Single Frequency Precise Point Positioning Applications: Egyptian Case Study." Artificial Satellites 53, no. 4 (December 1, 2018): 141–57. http://dx.doi.org/10.2478/arsa-2018-0011.
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Abstract The positioning accuracy of single frequency precise point positioning (SFPPP) attributes mainly to the ionosphere error, which strongly affects GNSS signals. When GNSS signals pass through the various ionosphere layers, they will be bent and their speed will be changed due to dispersive nature of ionosphere. To correct the ionosphere error, it is common to use Klobuchar ionosphere model or Global Ionosphere Maps (GIM). However, Klobuchar can deal with only about 50% of the Ionosphere effect and global Ionosphere maps are often inadequate to describe detailed features of local ionosphere because of limited precision and resolution. In this paper, an enhanced local ionosphere model was developed relying on modeling of measurements from a dense Egyptian permanent tracking GNSS network in order to achieve high precision ionosphere delay correction. The performance of the developed enhanced Egyptian ionosphere model (EIM) was verified through multi-constellations SFPPP accuracy for static and kinematic modes. For static mode, 24 hours multi-constellations datasets collected at three selected stations, Alexandria, Cairo, and Aswan, in Egypt on February 27, 2017, to investigate the performance of the developed local ionospheric model in comparison with the Klobuchar, GIM and ionosphere free models. After session time of half an hour, the results show that the performance of static SFPPP based on the developed Egyptian ionospheric map (EIM) achieved a comparable accuracy WRT using ionosphere free model. While using EIM, achieved an improvements of (38%, 28%, and 42%) and (32%, 10%, and 37%) for accuracy of latitude, longitude, and altitude in comparison with using Klobuchar and GIM models, respectively For kinematic mode, datasets of 2 hours of observations with 1 second sampling rate were logged during vehicular test; the test was carried out on the ring road of the city of Cairo, Egypt, on September 16, 2017. After half an hour of kinematic SFPPP data-processing, the performance of using Egyptian ionospheric map (EIM) for ionosphere delay correction, achieved an improvements of three dimension coordinates of (83%, 47%, and 62%) and (57%, 65%, and 21%) with respect to using Klobuchar model and GIM model, respectively.
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Liu, Hao, Wang Gao, Weiwei Miao, Shuguo Pan, Xiaolin Meng, and Longlei Qiao. "Research on Reliable Long-Baseline NRTK Positioning Method Considering Ionospheric Residual Interpolation Uncertainty." Remote Sensing 15, no. 22 (November 14, 2023): 5353. http://dx.doi.org/10.3390/rs15225353.
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In the past few decades, network real-time kinematic (NRTK) positioning technology has developed rapidly. Generally, in the continuously operating reference stations (CORS) network, within a moderate baseline length, e.g., 80–100 km, atmospheric delay can be effectively processed through regional modeling and, thus, can support almost instantaneous centimeter-level NRTK positioning. However, in long-baseline CORS networks, especially during the active period of the ionosphere, ionospheric delays cannot be fully eliminated through modeling, leading to decreased NRTK positioning accuracy. To address this issue, this study proposes a long-baseline NRTK positioning method considering ionospheric residual interpolation uncertainty (IRIU). The method utilizes the ionospheric residual interpolation standard deviation (IRISTD) calculated during atmospheric delay modeling, then fits an IRISTD-related stochastic model through the fitting of the absolute values of the ionospheric delay modeling residuals and IRISTD. Finally, based on the ionosphere-weighted model, the IRISTD processed by the stochastic model is used to constrain the ionospheric pseudo-observations. This method achieves good comprehensive performance in handling ionospheric delay and model strength, and the advantage is validated through experiments using CORS data with baseline lengths ranging from 54 km to 106 km in western China and from 84 km to 180 km in AUSCORS data. Quantitative results demonstrate that, across the three sets of experiments, the proposed ionosphere-weighted model achieves an average increase in the fixed rate of 16.9% compared to the ionosphere-fixed model and 25.6% compared to the ionosphere-float model. In terms of positioning accuracy, the proposed model yields average improvements of 67.4%, 76.4%, and 66.0% in the N/E/U directions, respectively, compared to the ionosphere-fixed model, and average improvements of 21.0%, 32.0%, and 24.4%, respectively, compared to the ionosphere-float model. Overall, the proposed method can achieve better NRTK positioning performance in situations where ionospheric delay modeling is inaccurate, such as long baselines and ionospheric activity.
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Vybornov, F. I., and O. A. Sheiner. "Coronal mass ejections and high-speed solar wind streams effect on HF ionospheric communication channel." Journal of Physics: Conference Series 2131, no. 5 (December 1, 2021): 052096. http://dx.doi.org/10.1088/1742-6596/2131/5/052096.
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Abstract This article analyzes the degree of solar coronal mass ejections and high-speed solar wind streams influence on the ionospheric communication channel in the short-wavelength range. Regularities in the coronal mass ejections influence on the parameters of the ionosphere are revealed. It is shown that there is a decrease in the values of the used differential parameter of critical frequency of the ionosphere F2 layer after the onset of coronal mass ejections of the loop type, while no significant changes are observed from other types of coronal mass ejections. The contribution of the high-speed solar wind flux to the features of the behavior of ionospheric parameters is demonstrated. Deviations of critical frequency and maximum observed frequency of the ionosphere F2 layer indicate a change in conditions in the ionosphere, leading to disruption of radio communication in the short-wavelength range. The results of ground-based measurements of the ionospheric plasma parameters were obtained by the methods of oblique and vertical sounding of the ionosphere. The use of the method of oblique sounding made it possible to obtain data on the state of the ionosphere where there are no vertical sounding stations.
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Mitchell, C. N., I. K. Walker, S. E. Pryse, I. Kersley, I. W. McCrea, and T. B. Jones. "<i>Letter to the Editor:</i> First complementary observations by ionospheric tomography, the EISCAT Svalbard radar and the CUTLASS HF radar." Annales Geophysicae 16, no. 11 (November 30, 1998): 1519–22. http://dx.doi.org/10.1007/s00585-998-1519-2.
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Abstract. Experimental results are presented from ionospheric tomography, the EISCAT Svalbard radar and the CUTLASS HF radar. Tomographic measurements on 10 October 1996, showing a narrow, field-aligned enhancement in electron density in the post-noon sector of the dayside auroral zone, are related to a temporal increase in the plasma concentration observed by the incoherent scatter radar in the region where the HF radar indicated a low velocity sunwards convection. The results demonstrate the complementary nature of these three instruments for polar-cap ionospheric studies.Key words. Ionosphere · Auroral ionosphere · Polar ionosphere · Radio science (ionospheric physics)
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Jee, Geonhwa. "Fundamentals of Numerical Modeling of the Mid-latitude Ionosphere." Journal of Astronomy and Space Sciences 40, no. 1 (March 2023): 11–18. http://dx.doi.org/10.5140/jass.2023.40.1.11.
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The ionosphere is one of the key components of the near-Earth’s space environment and has a practical consequence to the human society as a nearest region of the space environment to the Earth. Therefore, it becomes essential to specify and forecast the state of the ionosphere using both the observations and numerical models. In particular, numerical modeling of the ionosphere is a prerequisite not only for better understanding of the physical processes occurring within the ionosphere but also for the specification and forecast of the space weather. There are several approaches for modeling the ionosphere, including data-based empirical modeling, physics-based theoretical modeling and data assimilation modeling. In this review, these three types of the ionospheric model are briefly introduced with recently available models. And among those approaches, fundamental aspects of the physics-based ionospheric model will be described using the basic equations governing the mid-latitude ionosphere. Then a numerical solution of the equations will be discussed with required boundary conditions.
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Ясюкевич, Юрий, Yury Yasyukevich, Илья Живетьев, and Ilya Zhivetiev. "Using network technology for studying the ionosphere." Solnechno-Zemnaya Fizika 1, no. 3 (September 27, 2015): 21–27. http://dx.doi.org/10.12737/10545.
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One of the key problems of ionosphere physics is the coupling between different ionospheric regions. We apply networks technology for studying the coupling of changing ionospheric dynamics in different regions. We used data from global ionosphere maps (GIM) of total electron content (TEC) produced by CODE for 2005–2010. Distribution of cross-correlation function maxima of TEC variations is not simple. This distribution allows us to reveal two levels of ionosphere coupling: «strong» (r>0.9) and «weak» (r>0.72). The ionosphere of the Arctic region upper 50° magnetic latitude is characterized by a «strong» coupling. In the Southern hemisphere, a similar region is bigger. «Weak» coupling is typical for the whole Southern hemisphere. In North America there is an area where TEC dynamics is «strongly» correlated inside and is not correlated with other ionospheric regions.
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Lu, Shikun, Hao Zhang, Xihai Li, Yihong Li, Chao Niu, Xiaoyun Yang, and Daizhi Liu. "Complex network description of the ionosphere." Nonlinear Processes in Geophysics 25, no. 1 (March 22, 2018): 233–40. http://dx.doi.org/10.5194/npg-25-233-2018.
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Abstract. Complex networks have emerged as an essential approach of geoscience to generate novel insights into the nature of geophysical systems. To investigate the dynamic processes in the ionosphere, a directed complex network is constructed, based on a probabilistic graph of the vertical total electron content (VTEC) from 2012. The results of the power-law hypothesis test show that both the out-degree and in-degree distribution of the ionospheric network are not scale-free. Thus, the distribution of the interactions in the ionosphere is homogenous. None of the geospatial positions play an eminently important role in the propagation of the dynamic ionospheric processes. The spatial analysis of the ionospheric network shows that the interconnections principally exist between adjacent geographical locations, indicating that the propagation of the dynamic processes primarily depends on the geospatial distance in the ionosphere. Moreover, the joint distribution of the edge distances with respect to longitude and latitude directions shows that the dynamic processes travel further along the longitude than along the latitude in the ionosphere. The analysis of “small-world-ness” indicates that the ionospheric network possesses the small-world property, which can make the ionosphere stable and efficient in the propagation of dynamic processes.
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Kim, Mingyu, and Jeongrae Kim. "SBAS-Aided GPS Positioning with an Extended Ionosphere Map at the Boundaries of WAAS Service Area." Remote Sensing 13, no. 1 (January 5, 2021): 151. http://dx.doi.org/10.3390/rs13010151.
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Space-based augmentation system (SBAS) provides correction information for improving the global navigation satellite system (GNSS) positioning accuracy in real-time, which includes satellite orbit/clock and ionospheric delay corrections. At SBAS service area boundaries, the correction is not fully available to GNSS users and only a partial correction is available, mostly satellite orbit/clock information. By using the geospatial correlation property of the ionosphere delay information, the ionosphere correction coverage can be extended by a spatial extrapolation algorithm. This paper proposes extending SBAS ionosphere correction coverage by using a biharmonic spline extrapolation algorithm. The wide area augmentation system (WAAS) ionosphere map is extended and its ionospheric delay error is compared with the GPS Klobuchar model. The mean ionosphere error reduction at low latitude is 52.3%. The positioning accuracy of the extended ionosphere correction method is compared with the accuracy of the conventional SBAS positioning method when only a partial set of SBAS corrections are available. The mean positioning error reduction is 44.8%, and the positioning accuracy improvement is significant at low latitude.
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Long, Yanchen, Qinghui Zhang, Zhengquan Dai, and Jian Rong. "Investigation of Ionospheric Disturbance and Seismic Events Based on Machine Learning." Highlights in Science, Engineering and Technology 9 (September 30, 2022): 37–42. http://dx.doi.org/10.54097/hset.v9i.1712.
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Earthquakes are natural disasters that endanger human life and cause the greatest loss of property. The study of anomalous disturbance of the ionosphere, one of the pre-earthquake anomalies, will help to further study the coupling effect on the ionosphere before the earthquake. This paper focuses on the analysis of the importance and influence of various parameters inside the seismic ionosphere under earthquake conditions, constructs a classification and prediction model of seismic ionospheric anomalies based on the gradient boosting decision tree GBDT algorithm, and analyzes the pre-earthquake ionospheric data. , the results show that NmE, nHe+, foF2 and TEC are important influencing factors, which lays a certain foundation for the further study of the internal structure and parameters of the pre-earthquake ionosphere
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Shen, Emma, Dominic Anstey, Eloy de Lera Acedo, Anastasia Fialkov, and Will Handley. "Quantifying ionospheric effects on global 21-cm observations." Monthly Notices of the Royal Astronomical Society 503, no. 1 (February 19, 2021): 344–53. http://dx.doi.org/10.1093/mnras/stab429.
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ABSTRACT We modelled the two major layer of Earth’s ionosphere, the F-layer and the D-layer, by a simplified spatial model with temporal variance to study the chromatic ionospheric effects on global 21-cm observations. From the analyses, we found that the magnitude of the ionospheric disruptions due to ionospheric refraction and absorption can be greater than the expected global 21-cm signal, and the variation of its magnitude can differ, depending on the ionospheric conditions. Within the parameter space adopted in the model, the shape of the global 21-cm signal is distorted after propagating through the ionosphere, while its amplitude is weakened. It is observed that the ionospheric effects do not cancel out over time, and thus should be accounted for in the foreground calibration at each timestep to account for the chromaticity introduced by the ionosphere.
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Håkansson, Martin. "Nadir-Dependent GNSS Code Biases and Their Effect on 2D and 3D Ionosphere Modeling." Remote Sensing 12, no. 6 (March 19, 2020): 995. http://dx.doi.org/10.3390/rs12060995.
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Recent publications have shown that group delay variations are present in the code observables of the BeiDou system, as well as to a lesser degree in the code observables of the global positioning system (GPS). These variations could potentially affect precise point positioning, integer ambiguity resolution by the Hatch–Melbourne–Wübbena linear combination, and total electron content estimation for ionosphere modeling from global navigation satellite system (GNSS) observations. The latter is an important characteristic of the ionosphere and a prerequisite in some applications of precise positioning. By analyzing the residuals from total electron content estimation, the existence of group delay variations was confirmed by a method independent of the methods previously used. It also provides knowledge of the effects of group delay variations on ionosphere modeling. These biases were confirmed both for two-dimensional ionosphere modeling by the thin shell model, as well as for three-dimensional ionosphere modeling using tomographic inversion. BeiDou group delay variations were prominent and consistent in the residuals for both the two-dimensional and three-dimensional case of ionosphere modeling, while GPS group delay variations were smaller and could not be confirmed due to the accuracy limitations of the ionospheric models. Group delay variations were, to a larger extent, absorbed by the ionospheric model when three-dimensional ionospheric tomography was performed in comparison with two-dimensional modeling.
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Rothkaehl, H., A. Krakowski, I. Stanislawska, J. Błęcki, M. Parrot, J. J. Berthelier, and J. P. Lebreton. "Wave and plasma measurements and GPS diagnostics of the main ionospheric trough as a hybrid method used for Space Weather purposes." Annales Geophysicae 26, no. 2 (February 26, 2008): 295–304. http://dx.doi.org/10.5194/angeo-26-295-2008.
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Abstract. The region of the main ionospheric trough is a unique region of the ionosphere, where different types of waves and instabilities can be generated. This region of the ionosphere acts like a lens, focusing a variety of indicators from the equator of plasmapause and local ionospheric plasma. This paper reports the results of monitoring the mid-latitude trough structure, dynamics and wave activity. For these purposes, the data gathered by the currently-operating DEMETER satellite and past diagnostics located on IK-19, Apex, and MAGION-3 spacecraft, as well as TEC measurements were used. A global-time varying picture of the ionospheric trough was reconstructed using the sequence of wave spectra registered and plasma measurements in the top-side ionosphere. The authors present the wave activity from ULF frequency band to the HF frequency detected inside the trough region and discuss its properties during geomagnetic disturbances. It is thought that broadband emissions are correlated with low frequency radiation, which is excited by the wave-particle interaction in the equatorial plasmapause and moves to the ionosphere along the geomagnetic field line. In the ionosphere, the suprathermal electrons can interact with these electrostatic waves and excite electron acoustic waves or HF longitudinal plasma waves. Furthermore, the electron density trough can provide useful data on the magnetosphere ionosphere dynamics and morphology and, in consequence, can be used for Space Weather purposes.
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Aburjania, G. D., K. Z. Chargazia, G. V. Jandieri, A. G. Khantadze, and O. A. Kharshiladze. "On the new modes of planetary-scale electromagnetic waves in the ionosphere." Annales Geophysicae 22, no. 4 (April 2, 2004): 1203–11. http://dx.doi.org/10.5194/angeo-22-1203-2004.
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Abstract. Using an analogy method the frequencies of new modes of the electromagnetic planetary-scale waves (with a wavelength of 103 km or more), having a weather forming nature, are found at different ionospheric altitudes. This method gives the possibility to determine spectra of ionospheric electromagnetic perturbations directly from the dynamic equations without solving the general dispersion equation. It is shown that the permanently acting factor-latitude variation of the geomagnetic field generates fast and slow weakly damping planetary electromagnetic waves in both the E- and F-layers of the ionosphere. The waves propagate eastward and westward along the parallels. The fast waves have phase velocities (1–5)km s–1 and frequencies (10–1–10–4), and the slow waves propagate with velocities of the local winds with frequencies (10–4–10–6)s–1 and are generated in the E-region of the ionosphere. Fast waves having phase velocities (10-1500)km s–1 and frequencies (1–10–3)s–1 are generated in the F-region of the ionosphere. The waves generate the geomagnetic pulsations of the order of one hundred nanoTesla by magnitude. The properties and parameters of the theoretically studied electromagnetic waves agree with those of large-scale ultra-low frequency perturbations observed experimentally in the ionosphere. Key words. Ionosphere (ionospheric disturbances; waves propagation; ionosphere atmosphere interactions)
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Denisenko, V. V., M. Y. Boudjada, M. Horn, E. V. Pomozov, H. K. Biernat, K. Schwingenschuh, H. Lammer, G. Prattes, and E. Cristea. "Ionospheric conductivity effects on electrostatic field penetration into the ionosphere." Natural Hazards and Earth System Sciences 8, no. 5 (September 17, 2008): 1009–17. http://dx.doi.org/10.5194/nhess-8-1009-2008.
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Abstract. The classic approach to calculate the electrostatic field penetration, from the Earth's surface into the ionosphere, is to consider the following equation ∇·(σ·∇Φ)=0 where σ and Φ are the electric conductivity and the potential of the electric field, respectively. The penetration characteristics strongly depend on the conductivities of atmosphere and ionosphere. To estimate the electrostatic field penetration up to the orbital height of DEMETER satellite (about 700 km) the role of the ionosphere must be analyzed. It is done with help of a special upper boundary condition for the atmospheric electric field. In this paper, we investigate the influence of the ionospheric conductivity on the electrostatic field penetration from the Earth's surface into the ionosphere. We show that the magnitude of the ionospheric electric field penetrated from the ground is inverse proportional to the value of the ionospheric Pedersen conductance. So its typical value in day-time is about hundred times less than in night-time.
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Wang, Zhe, Qing Jin Ma, Cun Shen, Jing Fan, Chun Hua Jiang, and Chen Zhou. "Research on Visualization of Characteristic Parameters of Ionosphere." Applied Mechanics and Materials 614 (September 2014): 676–80. http://dx.doi.org/10.4028/www.scientific.net/amm.614.676.
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In this article, the author uses computer graphics visual programming method and visually expresses ionospheric characteristic parameters. Firstly, the significance of visualization of ionospheric characteristic parameters was described, then visualization process and methods were discussed, and finally the results of visualization of ionospheric parameters in typical conditions were given. The results show that visualization method of ionosphere characteristic parameters can directly reflect ionospheric electron density, electron temperature and other parameters, which is conductive to an intuitive understanding of various physical phenomena in ionosphere.
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Zhang, Z., R. T. Desai, O. Shebanits, F. L. Johansson, Y. Miyake, and H. Usui. "Simulating Secondary Electron and Ion Emission from the Cassini Spacecraft in Saturn’s Ionosphere." Planetary Science Journal 4, no. 6 (June 1, 2023): 105. http://dx.doi.org/10.3847/psj/acd844.
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Abstract The Cassini spacecraft’s Grand Finale flybys through Saturn’s ionosphere provided unprecedented insight into the composition and dynamics of the gas giant’s upper atmosphere and a novel and complex spacecraft–plasma interaction. In this article, we further study Cassini’s interaction with Saturn’s ionosphere using three-dimensional particle-in-cell simulations. We focus on how electrons and ions, emitted from spacecraft surfaces due to the high-velocity impact of atmospheric water molecules, could have affected the spacecraft potential and low-energy plasma measurements. The simulations show emitted electrons extend upstream along the magnetic field, and for sufficiently high emission rates, charge the spacecraft to positive potentials. The lack of accurate emission rates and characteristics, however, makes differentiation between the prominence of secondary electron emission and ionospheric charged dust populations, which induce similar charging effects, difficult for Cassini. These results provide further context for Cassini’s final measurements and highlight the need for future laboratory studies to support high-velocity flyby missions through planetary and cometary ionospheres.
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Mochalov, Vladimir, and Anastasia Mochalova. "Application of deep learning methods to predict ionosphere parameters in real time." E3S Web of Conferences 196 (2020): 02007. http://dx.doi.org/10.1051/e3sconf/202019602007.
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In this paper, the previously obtained results on recognition of ionograms using deep learning are expanded to predict the parameters of the ionosphere. After the ionospheric parameters have been identified on the ionogram using deep learning in real time, we can predict the parameters for some time ahead on the basis of the new data obtained Examples of predicting the ionosphere parameters using an artificial recurrent neural network architecture long short-term memory are given. The place of the block for predicting the parameters of the ionosphere in the system for analyzing ionospheric data using deep learning methods is shown.
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Wang, Chen, Zhang, Meng, and Wang. "Performance of Selected Ionospheric Models in Multi-Global Navigation Satellite System Single-Frequency Positioning over China." Remote Sensing 11, no. 17 (September 3, 2019): 2070. http://dx.doi.org/10.3390/rs11172070.
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Ionospheric delay as the major error source needs to be properly handled in multi-GNSS (Global Navigation Satellite System) single-frequency positioning and the different ionospheric models exhibit apparent performance difference. In this study, two single-frequency positioning solutions with different ionospheric corrections are utilized to comprehensively analyze the ionospheric delay effects on multi-frequency and multi-constellation positioning performance, including standard point positioning (SPP) and ionosphere-constrained precise point positioning (PPP). The four ionospheric models studied are the GPS broadcast ionospheric model (GPS-Klo), the BDS (BeiDou Navigation Satellite System) broadcast ionospheric model (BDS-Klo), the BDS ionospheric grid model (BDS-Grid) and the Global Ionosphere Maps (GIM) model. Datasets are collected from 10 stations over one month in 2019. The solar remained calm and the ionosphere was stable during the test period. The experimental results show that for single-frequency SPP, the GIM model achieves the best accuracy, and the positioning accuracy of the BDS-Klo and BDS-Grid model is much better than the solution with GPS-Klo model in the N and U components. For the single-frequency PPP performance, the average convergence time of the ionosphere-constrained PPP is much reduced compared with the traditional PPP approach, where the improvements are of 11.2%, 11.9%, 21.3% and 39.6% in the GPS-Klo-, BDS-Klo-, BDS-Grid- and GIM-constrained GPS + GLONASS + BDS single-frequency PPP solutions, respectively. Furthermore, the positioning accuracy of the BDS-Grid- and GIM-constrained PPP is generally the same as the ionosphere-free combined single-frequency PPP. Through the combination of GPS, GLONASS and BDS, the positioning accuracy and convergence performance for all single-system single-frequency SPP/PPP solutions can be effectively improved.
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Wild, J. A., S. E. Milan, S. W. H. Cowley, M. W. Dunlop, C. J. Owen, J. M. Bosqued, M. G. G. T. Taylor, et al. "Coordinated interhemispheric SuperDARN radar observations of the ionospheric response to flux transfer events observed by the Cluster spacecraft at the high-latitude magnetopause." Annales Geophysicae 21, no. 8 (August 31, 2003): 1807–26. http://dx.doi.org/10.5194/angeo-21-1807-2003.
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Abstract. At 10:00 UT on 14 February 2001, the quartet of ESA Cluster spacecraft were approaching the Northern Hemisphere high-latitude magnetopause in the post-noon sector on an outbound trajectory. At this time, the interplanetary magnetic field incident upon the dayside magnetopause was oriented southward and duskward (BZ negative, BY positive), having turned from a northward orientation just over 1 hour earlier. As they neared the magnetopause the magnetic field, electron, and ion sensors on board the Cluster spacecraft observed characteristic field and particle signatures of magnetospheric flux transfer events (FTEs). Following the traversal of a boundary layer and the magnetopause, the spacecraft went on to observe further signatures of FTEs in the magnetosheath. During this interval of ongoing pulsed reconnection at the high-latitude post-noon magnetopause, the footprints of the Cluster spacecraft were located in the fields-of-view of the SuperDARN Finland and Syowa East radars located in the Northern and Southern Hemispheres, respectively. This study extends upon the initial survey of Wild et al. (2001) by comparing for the first time in situ magnetic field and plasma signatures of FTEs (here observed by the Cluster 1 spacecraft) with the simultaneous flow modulations in the conjugate ionospheres in the two hemispheres. During the period under scrutiny, the flow disturbances in the conjugate ionospheres are manifest as classic "pulsed ionospheric flows" (PIFs) and "poleward moving radar auroral forms" (PMRAFs). We demonstrate that the ionospheric flows excited in response to FTEs at the magnetopause are not those expected for a spatially limited reconnection region, somewhere in the vicinity of the Cluster 1 spacecraft. By examining the large- and small-scale flows in the high-latitude ionosphere, and the inter-hemispheric correspondence exhibited during this interval, we conclude that the reconnection processes that result in the generation of PIFs/PMRAFs must extend over many (at least 4) hours of magnetic local time on the pre- and post-noon magnetopause.Key words. Ionosphere (plasma convection) – Magnetospheric physics (magnetosphere-ionosphere interactions; magnetospheric configuration and dynamics)
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Ridley, A. J., T. I. Gombosi, and D. L. DeZeeuw. "Ionospheric control of the magnetosphere: conductance." Annales Geophysicae 22, no. 2 (January 1, 2004): 567–84. http://dx.doi.org/10.5194/angeo-22-567-2004.
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Abstract. It is well known that the ionosphere plays a role in determining the global state of the magnetosphere. The ionosphere allows magnetospheric currents to close, thereby allowing magnetospheric convection to occur. The amount of current which can be carried through the ionosphere is mainly determined by the ionospheric conductivity. This paper starts to quantify the nonlinear relationship between the ionospheric conductivity and the global state of the magnetosphere. It is found that the steady-state magnetosphere acts neither as a current nor as a voltage generator; a uniform Hall conductance can influence the potential pattern at low latitudes, but not at high latitude; the EUV generated conductance forces the currents to close in the sunlight, while the potential is large on the nightside; the solar generated Hall conductances cause a large asymmetry between the dawn and dusk potential, which effects the pressure distribution in the magnetosphere; a uniform polar cap potential removes some of this asymmetry; the potential difference between solar minimum and maximum is ∼11%; and the auroral precipitation can be related to the local field-aligned current through an exponential function. Key words. Ionosphere (ionosphere-magnetosphere interactions; modelling and forecasting; polar ionosphere)
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Riabova, S. A., E. V. Olshanskaya, and S. L. Shalimov. "Response of the Lower and Upper Ionosphere to Earthquakes in Turkey on February 6, 2023." Физика земли 2023, no. 6 (November 1, 2023): 153–62. http://dx.doi.org/10.31857/s0002333723060182.
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Abstract—Ground-based magnetometers and ionospheric radio probing by means of GPS were used to analyze and interpret specific variations of the geomagnetic field and the total electron content of the ionosphere during strong catastrophic earthquakes in Turkey on February 6, 2023. It is shown that the ionospheric responses to these earthquakes recorded at distances of 1200–1600 km from the epicentre in the lower ionosphere and at distances of up to 500 km from the epicentre in the upper ionosphere can be interpreted in terms of the propagation of the Rayleigh seismic wave and atmospheric waves – shock, acoustic and internal, that is, those waves that are generated by the earthquake itself. The energy of seismic events was estimated from the ionospheric response.
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Villain, J. P., R. André, M. Pinnock, R. A. Greenwald, and C. Hanuise. "A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars." Annales Geophysicae 20, no. 11 (November 30, 2002): 1769–81. http://dx.doi.org/10.5194/angeo-20-1769-2002.
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Abstract. The HF radars of the Super Dual Auroral Radar Network (SuperDARN) provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; ionospheric irregularities)
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Surkov, Vadim, and Vyacheslav Pilipenko. "Can seismogenic atmospheric current influence the ionosphere?" Annals of Geophysics 67, no. 1 (May 21, 2024): PA107. http://dx.doi.org/10.4401/ag-9031.
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The question of whether earthquake precursors can arise in the ionosphere is of a special interest in geophysics. Despite numerous encouraging reports on seismo-ionospheric effects, the mechanism of the lithosphere-atmosphere-ionosphere coupling (LAIC) during the crust destruction phase was not revealed yet. One of hypothesis assumes that a seismogenic current transfers an abnormal electric field from the near-surface atmosphere to the ionosphere prior to an earthquake occurrence. This current can be caused by the air ionization due to enhancement of radon gas emission from the soil or upward movement of charged atmospheric aerosols. Here we present a theoretical model of the spatial structure of the electric field in the atmosphere and bottom ionosphere driven by a vertical external current in the lower atmosphere. Perturbation of electric field in the ionosphere has been derived in the approximation of the "thin" E-layer. Simple analytical estimates have been obtained that relate the horizontal electric field in the ionosphere, vertical electric field on the ground, and parameters of the external current. The electric field attenuation with altitude is caused by the increase of atmospheric conductivity and the horizontal spreading of current. The estimates obtained enable one to evaluate the feasibility of anomalous variations of electric fields in the ionosphere related to forthcoming earthquakes. The analysis has shown that the hypothesis on aerosol upward convection as a cause of ionospheric anomalies seems unrealistic. To interpret the occurrence of significant ionospheric anomalies it would be necessary to assume the presence of too large currents and electric fields in the lower atmosphere that had never been observed during non-thunderstorm periods.
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Zhivetiev, Ilya V., and Yury V. Yasyukevich. "Network Theory to Reveal Ionospheric Anomalies over North America and Australia." Atmosphere 13, no. 8 (August 22, 2022): 1333. http://dx.doi.org/10.3390/atmos13081333.
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There are significant challenges to model the ionosphere due to different anomalies, especially under the increasing requirements for precision level. We used network theory to construct an ionospheric network analysis based on the data of global ionospheric maps for the period from 1998 to 2015. The network approach revealed different domains in the ionosphere. Besides the well-known equatorial anomaly, we revealed two more essential areas with “anomalous” behavior in the total electron content (TEC). Both anomalies are located at mid-latitudes: the first over most of North America, and the second one over the southeast part of Australia and the adjacent part of the Indian Ocean. The revealed areas partly coincide with the winter anomaly regions. Our results demonstrate that complex ionosphere/magnetic field/neutral atmosphere interaction can result in atypical ionosphere dynamics in huge areas.
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Okoh, D. I., L. A. McKinnell, and P. J. Cilliers. "Developing an ionospheric map for South Africa." Annales Geophysicae 28, no. 7 (July 12, 2010): 1431–39. http://dx.doi.org/10.5194/angeo-28-1431-2010.
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Abstract. The development of a map of the ionosphere over South Africa is presented in this paper. The International Reference Ionosphere (IRI) model, South African Bottomside Ionospheric Model (SABIM), and measurements from ionosondes in the South African Ionosonde Network, were combined within their own limitations to develop an accurate representation of the South African ionosphere. The map is essentially in the form of a computer program that shows spatial and temporal representations of the South African ionosphere for a given set of geophysical parameters. A validation of the map is attempted using a comparison of Total Electron Content (TEC) values derived from the map, from the IRI model, and from Global Positioning System (GPS) measurements. It is foreseen that the final South African ionospheric map will be implemented as a Space Weather product of the African Space Weather Regional Warning Centre.
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Li, Haimeng, Jing-Song Wang, Zhou Chen, Lianqi Xie, Fan Li, and Tongji Zheng. "The Contribution of Geomagnetic Activity to Ionospheric foF2 Trends at Different Phases of the Solar Cycle by SWM." Atmosphere 11, no. 6 (June 11, 2020): 616. http://dx.doi.org/10.3390/atmos11060616.
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Solar activity dominates the temporal variability of ionospheric properties, which makes it difficult to identify and isolate the effects of geomagnetic activity on the ionosphere. Therefore, the latter effects on the ionosphere are still unclear. Here, we use the spectral whitening method (SWM)—a proven approach to extract ionospheric perturbations caused by geomagnetic activity—to directly obtain, in isolation, the effects of geomagnetic activity. We study its contribution to the ionosphere for different phases of the solar cycle. The time lag between the solar and geomagnetic activities provides an opportunity to understand the contribution of geomagnetic activity to the perturbation of the ionosphere. The results suggest that this contribution to the ionosphere is significant when geomagnetic activity is at its maximum level, which usually happens in the declining phase of the solar cycle, but the contribution is very weak at the solar minimum and during the ascending phase. Then, by analyzing the contributions in different months, we find that the role of geomagnetic activity is larger around winter but smaller around summer.
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Neudegg, D. A., S. W. H. Cowley, S. E. Milan, T. K. Yeoman, M. Lester, G. Provan, G. Haerendel, et al. "A survey of magnetopause FTEs and associated flow bursts in the polar ionosphere." Annales Geophysicae 18, no. 4 (April 30, 2000): 416–35. http://dx.doi.org/10.1007/s00585-000-0416-0.
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Abstract. Using the Equator-S spacecraft and SuperDARN HF radars an extensive survey of bursty reconnection at the magnetopause and associated flows in the polar ionosphere has been conducted. Flux transfer event (FTE) signatures were identified in the Equator-S magnetometer data during periods of magnetopause contact in January and February 1998. Assuming the effects of the FTEs propagate to the polar ionosphere as geomagnetic field-aligned-currents and associated Alfvén-waves, appropriate field mappings to the fields-of-view of SuperDARN radars were performed. The radars observed discrete ionospheric flow channel events (FCEs) of the type previously assumed to be related to pulse reconnection. Such FCEs were associated with \\sim80% of the FTEs and the two signatures are shown to be statistically associated with greater than 99% confidence. Exemplary case studies highlight the nature of the ionospheric flows and their relation to the high latitude convection pattern, the association methodology, and the problems caused by instrument limitations.Key words: Ionosphere (polar ionosphere) · Magnetospheric physics (magnetosphere-ionosphere interaction; solar wind-magnetosphere interactions)
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Su, Ke, and Shuanggen Jin. "Three Dual-Frequency Precise Point Positioning Models for the Ionospheric Modeling and Satellite Pseudorange Observable-Specific Signal Bias Estimation." Remote Sensing 13, no. 24 (December 15, 2021): 5093. http://dx.doi.org/10.3390/rs13245093.
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Global Navigation Satellite System (GNSS) Precise Point Positioning (PPP) enables the estimation the ionospheric vertical total electron content (VTEC) as well as the by-product of the satellite Pseudorange observable-specific signal bias (OSB). The single-frequency PPP models, with the ionosphere-float and ionosphere-free approaches in ionospheric studies, have recently been discussed by the authors. However, the multi-frequency observations can improve the performances of the ionospheric research compared with the single-frequency approaches. This paper presents three dual-frequency PPP approaches using the BeiDou Navigation Satellite System (BDS) B1I/B3I observations to investigate ionospheric activities. Datasets collected from the globally distributed stations are used to evaluate the performance of the ionospheric modeling with the ionospheric single- and multi-layer mapping functions (MFs), respectively. The characteristics of the estimated ionospheric VTEC and BDS satellite pseudorange OSB are both analyzed. The results indicated that the three dual-frequency PPP models could all be applied to the ionospheric studies, among which the dual-frequency ionosphere-float PPP model exhibits the best performance. The three dual-frequency PPP models all possess the capacity for ionospheric applications in the GNSS community.
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Sánchez-Cano, B., O. Witasse, M. Herraiz, S. M. Radicella, J. Bauer, P. L. Blelly, and G. Rodríguez-Caderot. "Retrieval of ionospheric profiles from the Mars Express MARSIS experiment data and comparison with radio-occultation data." Geoscientific Instrumentation, Methods and Data Systems Discussions 2, no. 1 (January 25, 2012): 87–106. http://dx.doi.org/10.5194/gid-2-87-2012.
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Abstract. Since 2005 the Mars Advanced Radar and Ionospheric Sounding experiment (MARSIS) aboard Mars Express has acquired a unique data set on the ionosphere of Mars made up of ionospheric soundings taken by the instrument working in its Active Ionospheric Sounding (AIS) mode. These soundings play a role similar to those of modern Terrestrial digisondes in the analysis of our planet ionosphere and have allowed us to dramatically improve our knowledge about the Martian ionosphere. This paper describes this kind of data, which are available from the public Planetary Science Archive, and introduces the MAISDAT tool developed by the European Space Agency to analyze and derive the vertical profile of electron density. Comparisons with radio-occultation profiles obtained from Mars Express Radio Science instrument are performed to validate the procedure used in this study.
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Sánchez-Cano, B., O. Witasse, M. Herraiz, S. M. Radicella, J. Bauer, P. L. Blelly, and G. Rodríguez-Caderot. "Retrieval of ionospheric profiles from the Mars Express MARSIS experiment data and comparison with radio occultation data." Geoscientific Instrumentation, Methods and Data Systems 1, no. 1 (May 25, 2012): 77–84. http://dx.doi.org/10.5194/gi-1-77-2012.
Full textAbstract:
Abstract. Since 2005 the Mars Advanced Radar and Ionospheric Sounding experiment (MARSIS) aboard Mars Express has acquired a unique dataset on the ionosphere of Mars made up of ionospheric soundings taken by the instrument working in its active ionospheric sounding (AIS) mode. These soundings play a role similar to those of modern Terrestrial digisondes in the analysis of our planet ionosphere and have allowed us to dramatically improve our knowledge about the Martian ionosphere. This paper describes this kind of data, which are available from the public Planetary Science Archive, and introduces the MAISDAT tool developed by the European Space Agency to analyze and derive the vertical profile of electron density. Comparisons with radio occultation profiles obtained from Mars Express Radio Science instrument are performed to validate the procedure used in this study.
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Saka, Osuke. "A new scenario applying traffic flow analogy to poleward expansion of auroras." Annales Geophysicae 37, no. 3 (June 5, 2019): 381–87. http://dx.doi.org/10.5194/angeo-37-381-2019.
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Abstract. Transient westward electric fields from the magnetosphere generate equatorward plasma drifts of the order of kilometers per second in the auroral ionosphere. This flow channel extends in north–south directions and is produced in the initial pulse of Pi2 pulsations associated with the field line dipolarization. Drifts in the ionosphere of the order of kilometers per second that accumulated plasmas at the low-latitude end of the flow channel are of such large degree that possible vertical transport effects (including precipitation) along the field lines may be ignored. In this condition, we suggest that plasma compression in the ionosphere initiated the dynamic ionosphere. The dynamic ionosphere includes a nonlinear evolution of the compressed ionospheric plasmas, generation of field-aligned currents to satisfy the quasi-neutrality of the ionosphere, and parallel potentials associated with the excitation of an ion acoustic wave. We will study how the dynamic ionosphere created auroral expansion.