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Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques

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A special issue of Remote Sensing (ISSN 2072-4292). This special issue belongs to the section "Atmospheric Remote Sensing".

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 26494

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Special Issue Editors

Prof. Dr. Ehsan Forootan

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Guest Editor

Geodesy and Earth Observation Group, Department of Planning, Aalborg University, Rendsburggade 14, 9000 Aalborg, Denmark
Interests: satellite gravity; satellite altimetry; satellite remote-sensing data assimilation; calibration; inversion
Special Issues, Collections and Topics in MDPI journals

Prof. Michael Schmidt

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Guest Editor

Deutsches Geodätisches Forschungsinstitut (DGFI-TUM), Department of Aerospace and Geodesy, Technical University of Munich, Arcisstraße 21, 80333 München, Germany
Interests: atmosphere modelling; regional gravity field modelling

Assist. Prof. Benedikt S Soja

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Guest Editor

ETH Zürich, Robert-Gnehm-Weg 15, 8093 Zürich, Switzerland
Interests: ionosphere; geodetic reference frames; very long baseline interferometry; parameter estimation
Special Issues, Collections and Topics in MDPI journals

Dr. Chao Xiong

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Guest Editor

GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
Interests: ionosphere/thermosphere and their coupling; ionospheric plasma irregularities and scintillation; space weather

Assoc. Prof. Saeed Farzaneh

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Guest Editor

College of Engineering, University of Tehran, Tehran, Iran
Interests: GNSS remote sensing; ionosphere research; satellite geodesy

Special Issue Information

Dear Colleagues,

The ionosphere and the thermosphere are parts of a physically coupled system ranging from the Earth surface to the Sun. Understanding the ionosphere–thermosphere system requires (1) monitoring the upper atmosphere by a multitude of remote sensing satellite missions and (2) further developing mathematical techniques and tools. The goal will be to represent the spatial and temporal variations of ionospheric and thermospheric key parameters, such as the plasma density and temperature, the height of the F2 peak, the total electron content (TEC), etc., as well as the thermospheric neutral density (TND) and wind.

This Special Issue will address recent progress, current understanding, and future challenges of thermospheric and ionospheric research, including, in particular, the coupling processes. Special emphasis is laid on the modelling and forecasting of space weather time series, e.g., extreme ultraviolet (EUV) and X-ray radiations, coronal mass ejections (CME) or co-rotating interaction region (CIR) driven geomagnetic storms, and their impact on various parameters of the ionosphere-thermosphere system. Therefore, investigations concerning ground-based precise point positioning (PPP), and precise orbit determination (POD) for Low-Earth-orbiting (LEO) satellites, current and future missions that can be used to monitor the thermosphere and ionosphere, and space-weather effect studies can be presented. We encourage further contributions to the dynamo electric field, the variations of neutral and ion compositions on the bottom and top side of the ionosphere, and atmospheric gravity waves and tides. Furthermore, we invite contributions on the wind dynamo, electrodynamics, and disturbances, including plasma drift, equatorial spread F (plasma bubbles), and resultant scintillation.

Prof. Ehsan Forootan
Prof. Michael Schmidt
Assoc. Prof. Benedikt S Soja
Dr. Chao Xiong
Assoc. Prof. Saeed Farzaneh
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Remote Sensing is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Thermosphere/Ionosphere
space weather
coupling processes
satellite geodesy
in-situ observations
precise point positioning (PPP)
low-Earth-orbit (LEO)
orbit determination
total electron content (TEC)
thermospheric neutral density (TND)

Published Papers (10 papers)

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Research

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18 pages, 1428 KiB

Open AccessArticle

The Influence of Solar X-ray Flares on SAR Meteorology: The Determination of the Wet Component of the Tropospheric Phase Delay and Precipitable Water Vapor

by Aleksandra Nina, Jelena Radović, Giovanni Nico, Luka Č. Popović, Milan Radovanović, Pier Francesco Biagi and Dejan Vinković

Remote Sens. 2021, 13(13), 2609; https://doi.org/10.3390/rs13132609 - 02 Jul 2021

Cited by 2 | Viewed by 1700

Abstract

In this work, we study the impact of high-energy radiation induced by solar X-ray flares on the determination of the temporal change in precipitable water vapor (

Δ

PWV) as estimated using the synthetic aperture radar (SAR) meteorology technique. As recent research shows, [...] Read more.

In this work, we study the impact of high-energy radiation induced by solar X-ray flares on the determination of the temporal change in precipitable water vapor (

Δ

PWV) as estimated using the synthetic aperture radar (SAR) meteorology technique. As recent research shows, this radiation can significantly affect the ionospheric D-region and induces errors in the estimation of the total electron content (TEC) by the applied models. Consequently, these errors are reflected in the determination of the phase delay and in many different types of measurements and models, including calculations of meteorological parameters based on SAR observations. The goal of this study is to quantify the impact of solar X-ray flares on the estimation of

Δ

PWV and provide an estimate of errors induced if the vertical total electron content (VTEC) is obtained by single layer models (SLM) or multiple layer models (MLM) (these models do not include ionosphere properties below the altitude of 90 km as input parameters and cannot provide information about local disturbances in the D-region). The performed analysis is based on a known procedure for the determination of the D-region electron density (and, consequently, the vertical total electron content in the D-region (VTEC

_{D}

)) using ionospheric observations by very low frequency (VLF) radio waves. The main result indicates that if the D-region, perturbed by medium-sized and intense X-ray flares, is not modeled, errors occur in the determination of

Δ

PWV. This study emphasizes the need for improved MLMs for the estimation of the TEC, including observational data at D-region altitudes during medium-sized and intense X-ray flare events. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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16 pages, 7252 KiB

Open AccessArticle

Ionosonde Observations of Spread F and Spread Es at Low and Middle Latitudes during the Recovery Phase of the 7–9 September 2017 Geomagnetic Storm

by Lehui Wei, Chunhua Jiang, Yaogai Hu, Ercha Aa, Wengeng Huang, Jing Liu, Guobin Yang and Zhengyu Zhao

Remote Sens. 2021, 13(5), 1010; https://doi.org/10.3390/rs13051010 - 07 Mar 2021

Cited by 16 | Viewed by 2045

Abstract

This study presents observations of nighttime spread F/ionospheric irregularities and spread Es at low and middle latitudes in the South East Asia longitude of China sectors during the recovery phase of the 7–9 September 2017 geomagnetic storm. In this study, multiple observations, including a chain of three ionosondes located about the longitude of 100°E, Swarm satellites, and Global Navigation Satellite System (GNSS) ROTI maps, were used to study the development process and evolution characteristics of the nighttime spread F/ionospheric irregularities at low and middle latitudes. Interestingly, spread F and intense spread Es were simultaneously observed by three ionosondes during the recovery phase. Moreover, associated ionospheric irregularities could be observed by Swarm satellites and ground-based GNSS ionospheric TEC. Nighttime spread F and spread Es at low and middle latitudes might be due to multiple off-vertical reflection echoes from the large-scale tilts in the bottom ionosphere. In addition, we found that the periods of the disturbance ionosphere are ~1 h at ZHY station, ~1.5 h at LSH station and ~1 h at PUR station, respectively. It suggested that the large-scale tilts in the bottom ionosphere might be produced by LSTIDs (Large scale Traveling Ionospheric Disturbances), which might be induced by the high-latitude energy inputs during the recovery phase of this storm. Furthermore, the associated ionospheric irregularities observed by satellites and ground-based GNSS receivers might be caused by the local electric field induced by LSTIDs. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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Figure 1

12 pages, 2425 KiB

Open AccessArticle

Ionospheric Turbulence and the Equatorial Plasma Density Irregularities: Scaling Features and RODI

by Paola De Michelis, Giuseppe Consolini, Roberta Tozzi, Alessio Pignalberi, Michael Pezzopane, Igino Coco, Fabio Giannattasio and Maria Federica Marcucci

Remote Sens. 2021, 13(4), 759; https://doi.org/10.3390/rs13040759 - 18 Feb 2021

Cited by 11 | Viewed by 2656

Abstract

In the framework of space weather, the understanding of the physical mechanisms responsible for the generation of ionospheric irregularities is particularly relevant for their effects on global positioning and communication systems. Ionospheric equatorial plasma bubbles are one of the possible irregularities. In this work, using data from the ESA Swarm mission, we investigate the scaling features of electron density fluctuations characterizing equatorial plasma bubbles. Results strongly support a turbulence character of these structures and suggest the existence of a clear link between the observed scaling properties and the value of the Rate Of change of electron Density Index (RODI). This link is discussed, and RODI is proposed as a reliable proxy for the identification of plasma bubbles. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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20 pages, 24230 KiB

Open AccessArticle

Analysis of Atmospheric and Ionospheric Variations Due to Impacts of Super Typhoon Mangkhut (1822) in the Northwest Pacific Ocean

by Mohamed Freeshah, Xiaohong Zhang, Erman Şentürk, Muhammad Arqim Adil, B. G. Mousa, Aqil Tariq, Xiaodong Ren and Mervat Refaat

Remote Sens. 2021, 13(4), 661; https://doi.org/10.3390/rs13040661 - 11 Feb 2021

Cited by 20 | Viewed by 4006

Abstract

The Northwest Pacific Ocean (NWP) is one of the most vulnerable regions that has been hit by typhoons. In September 2018, Mangkhut was the 22nd Tropical Cyclone (TC) over the NWP regions (so, the event was numbered as 1822). In this paper, we investigated the highest amplitude ionospheric variations, along with the atmospheric anomalies, such as the sea-level pressure, Mangkhut’s cloud system, and the meridional and zonal wind during the typhoon. Regional Ionosphere Maps (RIMs) were created through the Hong Kong Continuously Operating Reference Stations (HKCORS) and International GNSS Service (IGS) data around the area of Mangkhut typhoon. RIMs were utilized to analyze the ionospheric Total Electron Content (TEC) response over the maximum wind speed points (maximum spots) under the meticulous observations of the solar-terrestrial environment and geomagnetic storm indices. Ionospheric vertical TEC (VTEC) time sequences over the maximum spots are detected by three methods: interquartile range method (IQR), enhanced average difference (EAD), and range of ten days (RTD) during the super typhoon Mangkhut. The research findings indicated significant ionospheric variations over the maximum spots during this powerful tropical cyclone within a few hours before the extreme wind speed. Moreover, the ionosphere showed a positive response where the maximum VTEC amplitude variations coincided with the cyclone rainbands or typhoon edges rather than the center of the storm. The sea-level pressure tends to decrease around the typhoon periphery, and the highest ionospheric VTEC amplitude was observed when the low-pressure cell covers the largest area. The possible mechanism of the ionospheric response is based on strong convective cells that create the gravity waves over tropical cyclones. Moreover, the critical change state in the meridional wind happened on the same day of maximum ionospheric variations on the 256th day of the year (DOY 256). This comprehensive analysis suggests that the meridional winds and their resulting waves may contribute in one way or another to upper atmosphere-ionosphere coupling. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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24 pages, 1793 KiB

Open AccessArticle

Quiet Ionospheric D-Region (QIonDR) Model Based on VLF/LF Observations

by Aleksandra Nina, Giovanni Nico, Srđan T. Mitrović, Vladimir M. Čadež, Ivana R. Milošević, Milan Radovanović and Luka Č. Popović

Remote Sens. 2021, 13(3), 483; https://doi.org/10.3390/rs13030483 - 29 Jan 2021

Cited by 15 | Viewed by 2390

Abstract

The ionospheric D-region affects propagation of electromagnetic waves including ground-based signals and satellite signals during its intensive disturbances. Consequently, the modeling of electromagnetic propagation in the D-region is important in many technological domains. One of sources of uncertainty in the modeling of the disturbed D-region is the poor knowledge of its parameters in the quiet state at the considered location and time period. We present the Quiet Ionospheric D-Region (QIonDR) model based on data collected in the ionospheric D-region remote sensing by very low/low frequency (VLF/LF) signals and the Long-Wave Propagation Capability (LWPC) numerical model. The QIonDR model provides both Wait’s parameters and the electron density in the D-region area of interest at a given daytime interval. The proposed model consists of two steps. In the first step, Wait’s parameters are modeled during the quiet midday periods as a function of the daily sunspot number, related to the long-term variations during solar cycle, and the seasonal parameter, providing the seasonal variations. In the second step, the output of the first step is used to model Wait’s parameters during the whole daytime. The proposed model is applied to VLF data acquired in Serbia and related to the DHO and ICV signals emitted in Germany and Italy, respectively. As a result, the proposed methodology provides a numerical tool to model the daytime Wait’s parameters over the middle and low latitudes and an analytical expression valid over a part of Europe for midday parameters. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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21 pages, 10241 KiB

Open AccessArticle

A Least Squares Solution to Regionalize VTEC Estimates for Positioning Applications

by Saeed Farzaneh and Ehsan Forootan

Remote Sens. 2020, 12(21), 3545; https://doi.org/10.3390/rs12213545 - 29 Oct 2020

Cited by 5 | Viewed by 2232

Abstract

A new approach is presented to improve the spatial and temporal resolution of the Vertical Total Electron Content (VTEC) estimates for regional positioning applications. The proposed technique utilises a priori information from the Global Ionosphere Maps (GIMs) of the Center for Orbit Determination in Europe (CODE), provided in terms of Spherical Harmonic (SH) coefficients of up to degree and order 15. Then, it updates the VTEC estimates using a new set of base-functions (with better resolution than SHs) while using the measurements of a regional GNSS network. To achieve the highest accuracy possible, our implementation is based on a transformation of the GIM/CODE VTECs to their equivalent coefficients in terms of (spherical) Slepian functions. These functions are band-limited and reflect the majority of signal energy inside an arbitrarily defined region, yet their orthogonal property is remained. Then, new dual-frequency GNSS measurements are introduced to a Least Squares (LS) updating step that modifies the Slepian VTEC coefficients within the region of interest. Numerical application of this study is demonstrated using a synthetic example and ground-based GPS data in South America. The results are also validated against the VTEC estimations derived from independent GPS stations (that are not used in the modelling), and the VTEC products of international centres. Our results indicate that, by using 62 GPS stations in South America, the ionospheric delay estimation can be considerably improved. For example, using the new VTEC estimates in a Precise Point Positioning (PPP) experiment improved the positioning accuracy compared to the usage of GIM/CODE and Klobuchar models. The reductions in the root mean squared of errors were ∼23% and 25% for a day with moderate solar activity while 26% and ∼35% for a day with high solar activity, respectively. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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17 pages, 1510 KiB

Open AccessArticle

Investigation of Daytime Total Electron Content Enhancements over the Asian-Australian Sector Observed from the Beidou Geostationary Satellite during 2016–2018

by Oluwaseyi Jimoh, Jiuhou Lei and Fuqing Huang

Remote Sens. 2020, 12(20), 3406; https://doi.org/10.3390/rs12203406 - 16 Oct 2020

Cited by 8 | Viewed by 1761

Abstract

This study focused on the investigation of daytime positive ionospheric disturbances and the recurrence of total electron content (TEC) enhancements. TEC data derived from the Beidou geostationary satellite over the Asian-Australian sector were used to study the occurrence of TEC enhancements during 2016–2018. The occurrence of TEC enhancements under quiet geomagnetic condition was analyzed. Furthermore, the occurrence of TEC enhancements during different geomagnetic storm phases was considered to address the question that relates to the recurrence of TEC enhancements during the recovery phase of geomagnetic storms. The seasonal variation of TEC enhancements displayed equinoctial and solstitial peaks at the middle and low latitudes respectively. Besides, there was no evident systematic latitudinal dependence in the occurrence of TEC enhancements, albeit at the equatorial station, nearly no TEC enhancement was observed under Kp < 3. Meanwhile, the occurrences during the main phases of the geomagnetic storms were significantly above the TEC enhancement baselines except at HKWS. The prominence of TEC enhancements during the main phase in comparison with the initial and recovery phases could be attributed to the effects of prompt penetration electric fields and equator-ward neutral winds. Moreover, the pattern of TEC enhancements during the storm recovery indicates the effects of chemical composition changes, winds, and the possible modulation from the lower atmospheric forcing. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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22 pages, 6115 KiB

Open AccessArticle

The Low-Latitude Plasma Irregularities after Sunrise from Multiple Observations in Both Hemispheres during the Recovery Phase of a Storm

by Weihua Luo, Chao Xiong, Jisheng Xu, Zhengping Zhu and Shanshan Chang

Remote Sens. 2020, 12(18), 2897; https://doi.org/10.3390/rs12182897 - 07 Sep 2020

Cited by 11 | Viewed by 2555

Abstract

The daytime plasma density disturbances in the low-latitude ionosphere, referred to as plasma irregularities, mainly occur during the nighttime and are an unusual phenomenon. Based on the observations from multiple low Earth orbiting (LEO) satellites, e.g., the Defense Meteorological Satellite Program (DMSP) F13 and F15, the first Satellite of the Republic of China (ROCSAT-1), the Gravity Recovery and the Climate Experiment (GRACE), and Challenging Mini-satellite Payload (CHAMP) satellites, as well as the ground-based Global Positioning System (GPS) receivers, we report a special event of low-latitude plasma irregularities that were observed after sunrise in the Pacific longitudes on 18 August, 2003, following a moderate geomagnetic storm. Observations from three ground-based GPS stations in both hemispheres showed remarkable total electron content (TEC) disturbances during 20:00 to 21:00 UT (around local sunrise), agreeing well with the in situ plasma density irregularities recorded by the nearby flying LEO satellites. The plasma irregularities observed by these LEO satellites showed quite different depletion intensities at different altitudes. We suggest that the plasma irregularities were freshly generated near sunrise hours due to the disturbance of the dynamo electric field (DDEF), evolving into the post-sunrise and morning sector, but were not the remnant of the plasma irregularities generated during the previous nighttime. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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25 pages, 1764 KiB

Open AccessEditor’s ChoiceArticle

Adaptive Modeling of the Global Ionosphere Vertical Total Electron Content

by Eren Erdogan, Michael Schmidt, Andreas Goss, Barbara Görres and Florian Seitz

Remote Sens. 2020, 12(11), 1822; https://doi.org/10.3390/rs12111822 - 04 Jun 2020

Cited by 15 | Viewed by 3323

Abstract

The Kalman filter (KF) is widely applied in (ultra) rapid and (near) real-time ionosphere modeling to meet the demand on ionosphere products required in many applications extending from navigation and positioning to monitoring space weather events and naturals disasters. The requirement of a prior definition of the stochastic models attached to the measurements and the dynamic models of the KF is a drawback associated with its standard implementation since model uncertainties can exhibit temporal variations or the time span of a given test data set would not be large enough. Adaptive methods can mitigate these problems by tuning the stochastic model parameters during the filter run-time. Accordingly, one of the primary objectives of our study is to apply an adaptive KF based on variance component estimation to compute the global Vertical Total Electron Content (VTEC) of the ionosphere by assimilating different ionospheric GNSS measurements. Secondly, the derived VTEC representation is based on a series expansion in terms of compactly supported B-spline functions. We highlight the morphological similarity of the spatial distributions and the magnitudes between VTEC values and the corresponding estimated B-spline coefficients. This similarity allows for deducing physical interpretations from the coefficients. In this context, an empirical adaptive model to account for the dynamic model uncertainties, representing the temporal variations of VTEC errors, is developed in this work according to the structure of B-spline coefficients. For the validation, the differential slant total electron content (dSTEC) analysis and a comparison with Jason-2/3 altimetry data are performed. Assessments show that the quality of the VTEC products derived by the presented algorithm is in good agreement, or even more accurate, with the products provided by IGS ionosphere analysis centers within the selected periods in 2015 and 2017. Furthermore, we show that the presented approach can be applied to different ionosphere conditions ranging from very high to low solar activity without concerning time-variable model uncertainties, including measurement error and process noise of the KF because the associated covariance matrices are computed in a self-adaptive manner during run-time. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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17 pages, 5283 KiB

Open AccessTechnical Note

Multi-Experiment Observations of Ionospheric Disturbances as Precursory Effects of the Indonesian Ms6.9 Earthquake on August 05, 2018

by Xuemin Zhang, Yalu Wang, Mohammed Yahia Boudjada, Jing Liu, Werner Magnes, Yulin Zhou and Xiaohui Du

Remote Sens. 2020, 12(24), 4050; https://doi.org/10.3390/rs12244050 - 11 Dec 2020

Cited by 28 | Viewed by 2375

Abstract

Taking the 2018 Ms6.9 Indonesia earthquake as a case study, the ionospheric perturbations in very low frequency (VLF) transmitters recorded by China Seismo-Electromagnetic Satellite (CSES) were mainly investigated, as well as the multi parameters of the plasma and electromagnetic field. The characteristics of electron density (Ne), GPS TEC, ULF electric field, ion drift velocity, and ionosphere height were extracted and compared with the features of the signal-noise ratio (SNR) from VLF transmitters of NWC at the southern hemisphere and JJI at the northern hemisphere. Most disturbances in VLF radio waves occurred along the orbits near the epicenter within 10 days before the earthquake. Along these orbits, we observed simultaneous modulations in the Ne and ULF electric field, as well as the changed ion drifting directions. There was also high spatial correspondence between both SNR and ionospheric height anomalies over the epicentral and its magnetic conjugate regions. Combined with the multi observations, these results suggest that the genesis of perturbations in signals emitted by VLF transmitters on satellite was more likely related to the overlapped electric field in the preparation area of the earthquake. Full article

(This article belongs to the Special Issue Observing and Modelling Ionosphere and Thermosphere Using In Situ and Remote Sensing Techniques)

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