Ionospheric Monitoring and Modelling for Space Weather

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Upper Atmosphere".

Deadline for manuscript submissions: closed (1 December 2021) | Viewed by 32229

Special Issue Editors

RALSpace, STFC Rurherford Appleton Laboratory, Oxfordshire OX11 0QX, UK
Interests: radio wave propagation and prediction; application of artificial neural networks to ionospheric forecasting, and Experiments to measure characteristics of the Earth’s ionosphere relevant to the operation of space weather systems
National Institute of Geophysics and Volcanology, 00143 Roma, Italy
Interests: ionospheric mapping and modelling; ionospheric prediction and forecasting; ionospheric monitoring; space weather

Special Issue Information

Dear Colleagues,

Over the last decades, our scientific understanding and user’s community appreciation of the ionospheric space weather and its impacts on Earth environment, some of the technological systems and human beings priority areas have changed considerably. With that realization (or In that recognition), we would like to draw your attention to the Special Issue on "Ionospheric Monitoring and Modelling for Space Weather" in the Atmosphere, an international peer-reviewed open access monthly journal published by MDPI (Multidisciplinary Digital Publishing Institute, Basel, Switzerland) with deadline for manuscript submissions: 15 May 2021.

This Special Issue focuses on monitoring, and current and future programs for space and ground-based observations of the Earth’s ionosphere proposing innovative ideas. It would also identify most important results and findings in the world-wide international domain that need additional examination and development in ionospheric weather mapping and modelling. These include selected review and featured papers on:

- General monitoring and modelling related topics;

- Geophysical conditions for enhanced hazard in ionospheric space weather;

- Physics and dynamics of the Earth’s ionosphere from equatorial to high latitude;

- Variability of radio wave propagation characteristics in the Earth’s ionosphere;

- Development of sophisticated methods and models related to the real-time ionospheric space weather service.

If you are interested to take advantage of this opportunity, please send us an email with a tentative title and short abstract by 31 December 2020.

We look forward to hear from you, Guest Editors

Dr. Ljiljana R. Cander
Dr. Bruno Zolesi
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. Atmosphere is an international peer-reviewed open access monthly 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 2400 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

  • Space Weather: Risk assessment; Natural hazards; Extreme events
  • Ionosphere: Ground- and space-based observations; Electron density morphology; Ionospheric indices; Models and maps; Storms; Low, mid and high Latitude Ionosphere; Waves and irregularities
  • Radio System Operation: Validation of the model prediction anf forecasting,; MUF analysis
  • GNSS: Total Electron Content (TEC); Global and regional maps

Published Papers (13 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Editorial

Jump to: Research

3 pages, 173 KiB  
Editorial
Ionospheric Monitoring and Modelling for Space Weather: An Introduction to the Special Issue
by Ljiljana R. Cander and Bruno Zolesi
Atmosphere 2022, 13(3), 477; https://doi.org/10.3390/atmos13030477 - 15 Mar 2022
Viewed by 1496
Abstract
Over the last decades, our scientific understanding and user’s community appreciation of the ionospheric space weather and its impacts on Earth’s environment, and some of the technological systems and human beings’ priority areas, have changed considerably [...] Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)

Research

Jump to: Editorial

11 pages, 370 KiB  
Article
Ionospheric Science: An Example of the Importance of Diversity in Approaches to Scientific Research
by Mike Hapgood
Atmosphere 2022, 13(3), 394; https://doi.org/10.3390/atmos13030394 - 27 Feb 2022
Cited by 4 | Viewed by 2609
Abstract
This paper discusses the strategic importance of contemporary ionospheric science. It outlines some key features of the evolution of the science from the first practical experiments in the 1920s through to the diverse inter-disciplinary science of today. This science includes fundamental studies of [...] Read more.
This paper discusses the strategic importance of contemporary ionospheric science. It outlines some key features of the evolution of the science from the first practical experiments in the 1920s through to the diverse inter-disciplinary science of today. This science includes fundamental studies of partially ionised plasmas and of the complex systems that arise when those plasmas are coupled to neutral atmospheres and magnetospheres. However, the science also has great potential to deliver societal benefits if the science can be refined to obtain a deep physical understanding of ionospheric phenomena and that understanding is then transitioned into use by operational services such as forecasts of ionospheric conditions. Thus, ionospheric science is now very similar in form to other environment sciences and, the same as them, needs to be positioned in a diverse scientific culture that supports the full range of science research, including not only curiosity-driven studies, but also targeted research to deepen our physical understanding to a level that is sufficient to enable a transition to operational services. That diversity also includes support for that transition and also facilitates feedback from operations teams to researchers. Such feedback can be a powerful stimulus for future research. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

15 pages, 4944 KiB  
Article
Global Monitoring of Ionospheric Weather by GIRO and GNSS Data Fusion
by Ivan Galkin, Adam Froń, Bodo Reinisch, Manuel Hernández-Pajares, Andrzej Krankowski, Bruno Nava, Dieter Bilitza, Kacper Kotulak, Paweł Flisek, Zishen Li, Ningbo Wang, David Roma Dollase, Alberto García-Rigo and Inez Batista
Atmosphere 2022, 13(3), 371; https://doi.org/10.3390/atmos13030371 - 23 Feb 2022
Cited by 19 | Viewed by 3253
Abstract
Prompt and accurate imaging of the ionosphere is essential to space weather services, given a broad spectrum of applications that rely on ionospherically propagating radio signals. As the 3D spatial extent of the ionosphere is vast and covered only fragmentarily, data fusion is [...] Read more.
Prompt and accurate imaging of the ionosphere is essential to space weather services, given a broad spectrum of applications that rely on ionospherically propagating radio signals. As the 3D spatial extent of the ionosphere is vast and covered only fragmentarily, data fusion is a strong candidate for solving imaging tasks. Data fusion has been used to blend models and observations for the integrated and consistent views of geosystems. In space weather scenarios, low latency of the sensor data availability is one of the strongest requirements that limits the selection of potential datasets for fusion. Since remote plasma sensing instrumentation for ionospheric weather is complex, scarce, and prone to unavoidable data noise, conventional 3D-var assimilative schemas are not optimal. We describe a novel substantially 4D data fusion service based on near-real-time data feeds from Global Ionosphere Radio Observatory (GIRO) and Global Navigation Satellite System (GNSS) called GAMBIT (Global Assimilative Model of the Bottomside Ionosphere with Topside estimate). GAMBIT operates with a few-minute latency, and it releases, among other data products, the anomaly maps of the effective slab thickness (EST) obtained by fusing GIRO and GNSS data. The anomaly EST mapping aids understanding of the vertical plasma restructuring during disturbed conditions. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Graphical abstract

15 pages, 3666 KiB  
Article
Evaluation of Empirical Atmospheric Models Using Swarm-C Satellite Data
by Lirong Yin, Lei Wang, Wenfeng Zheng, Lijun Ge, Jiawei Tian, Yan Liu, Bo Yang and Shan Liu
Atmosphere 2022, 13(2), 294; https://doi.org/10.3390/atmos13020294 - 09 Feb 2022
Cited by 71 | Viewed by 2890
Abstract
Swarm-C satellite, a new instrument for atmospheric study, has been the focus of many studies to evaluate its usage and accuracy. This paper takes the Swarm-C satellite as a research object to verify the Swarm-C accelerometer’s inversion results. This paper uses the two-row [...] Read more.
Swarm-C satellite, a new instrument for atmospheric study, has been the focus of many studies to evaluate its usage and accuracy. This paper takes the Swarm-C satellite as a research object to verify the Swarm-C accelerometer’s inversion results. This paper uses the two-row orbital elements density inversion to verify the atmospheric density accuracy results of the Swarm-C satellite accelerometer. After the accuracy of the satellite data is verified, this paper conducts comparative verification and empirical atmospheric model evaluation experiments based on the Swarm-C accelerometer’s inversion results. After comparing with the inversion results of the Swarm-C semi-major axis attenuation method, it is found that the atmospheric density obtained by inversion using the Swarm-C accelerometer is more dynamic and real-time. It shows that with more available data, the Swarm-C satellite could be a new high-quality instrument for related studies along with the well-established satellites. After evaluating the performance of the JB2008 and NRLMSISE-00 empirical atmospheric models using the Swarm-C accelerometer inversion results, it is found that the accuracy and real-time performance of the JB2008 model at the altitude where the Swarm-C satellite is located are better than the NRLMSISE-00 model. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

24 pages, 2803 KiB  
Article
Predicting the Effects of Solar Storms on the Ionosphere Based on a Comparison of Real-Time Solar Wind Data with the Best-Fitting Historical Storm Event
by Erik Schmölter and Jens Berdermann
Atmosphere 2021, 12(12), 1684; https://doi.org/10.3390/atmos12121684 - 16 Dec 2021
Cited by 9 | Viewed by 2434
Abstract
This study presents a new modeling approach that aims for long time predictions (more than 12 h) of ionospheric disturbances driven by solar storm events. The proposed model shall run in an operational framework to deliver fast and precise localized warnings for these [...] Read more.
This study presents a new modeling approach that aims for long time predictions (more than 12 h) of ionospheric disturbances driven by solar storm events. The proposed model shall run in an operational framework to deliver fast and precise localized warnings for these disturbances in the future. The solar wind data driven approach uses a data base of historical solar storm impacts covering two solar cycles to reconstruct future events and resulting ionospheric disturbances. The basic components of the model are presented and discussed in this study, and the strengths of the reconstruction based on historical events are presented by showing the good correlations for predicted and observed geomagnetic activity. Initial results on the ionospheric response are discussed for all historical events using global total electron content (GTEC) and in more detail using total electron content (TEC) maps for two specific case studies (including the St. Patrick’s Day geomagnetic storm during the 17 March 2015). Average root mean square error (RMSE) values of 3.90 and 5.21 TECU are calculated for these cases confirming good results for the current configuration of the model. Possible future improvements of the individual model parts, as well as the planned extensions and applications are discussed in detail. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

16 pages, 5729 KiB  
Article
Comparison of Seasonal foEs and fbEs Occurrence Rates Derived from Global Digisonde Measurements
by Dawn K. Merriman, Omar A. Nava, Eugene V. Dao and Daniel J. Emmons
Atmosphere 2021, 12(12), 1558; https://doi.org/10.3390/atmos12121558 - 25 Nov 2021
Cited by 10 | Viewed by 1245
Abstract
A global climatology of sporadic-E occurrence rates (ORs) based on ionosonde measurements is presented for the peak blanketing frequency, fbEs, and the ordinary mode peak frequency of the layer, foEs. ORs are calculated for a variety of sporadic-E frequency thresholds: no lower limit, [...] Read more.
A global climatology of sporadic-E occurrence rates (ORs) based on ionosonde measurements is presented for the peak blanketing frequency, fbEs, and the ordinary mode peak frequency of the layer, foEs. ORs are calculated for a variety of sporadic-E frequency thresholds: no lower limit, 3, 5, and 7 MHz. Seasonal rates are calculated from 64 Digisonde sites during the period 2006–2020 using ionograms either manually or automatically scaled with ARTIST-5. Both foEs and fbEs ORs peak in the Northern Hemisphere during the boreal summer, with a decrease by roughly a factor of 2–3 in fbEs rates relative to foEs rates without a lower threshold on the sporadic-E intensity. This ratio of foEs to fbEs OR increases with increasing sporadic-E intensity, up to a factor of 5 for the 7 MHz threshold. An asymmetry is observed with the Southern Hemisphere peaks during the austral summer, with slightly lower rates compared with the Northern Hemisphere during the boreal summer. A drastic decrease in ORs is observed for the higher intensity thresholds, such that the fbEs occurrence rates for 7 MHz are nearly zero during most locations and seasons. These updated occurrence rates can be used for future statistical comparisons with GPS radio occultation-based sporadic-E occurrence rates. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

21 pages, 2888 KiB  
Article
Long-Term Study on Medium-Scale Traveling Ionospheric Disturbances Observed over the South American Equatorial Region
by Patrick Essien, Cosme Alexandre Oliveira Barros Figueiredo, Hisao Takahashi, Cristiano Max Wrasse, Diego Barros, Nana Ama Browne Klutse, Solomon Otoo Lomotey, Toyese Tunde Ayorinde, Delano Gobbi and Anderson V. Bilibio
Atmosphere 2021, 12(11), 1409; https://doi.org/10.3390/atmos12111409 - 26 Oct 2021
Cited by 6 | Viewed by 2050
Abstract
Using data collected by the GNSS dual-frequency receivers network, de-trended TEC maps were generated to identify and characterize the medium-scale traveling ionospheric disturbances (MSTIDs) over the South American equatorial region (latitude: 0 to 15 S and longitude: 30 to [...] Read more.
Using data collected by the GNSS dual-frequency receivers network, de-trended TEC maps were generated to identify and characterize the medium-scale traveling ionospheric disturbances (MSTIDs) over the South American equatorial region (latitude: 0 to 15 S and longitude: 30 to 55 W) during solar cycle 24 (from January 2014 to December 2019). A total of 712 MSTIDs were observed during quiet geomagnetic conditions. The Frequency of occurrence of MSTID is high during the solar maximum and low in the minimum phase. This might be due to the solar cycle dependence of gravity wave activity in the lower atmosphere and gravity wave propagation conditions in the thermosphere. The predominant daytime MSTIDs, representing 80% of the total observations, occurred in winter (June-August season in the southern hemisphere) with the secondary peak in the equinox; while the evening time MSTIDs, representing 18% of the entire events, occurred in summer (December to February season) and equinox (March to May and September to November), and the remaining 2% of the MSTIDs were observed during nighttime. The seasonal variation of the MSTID events was attributed to the source mechanisms generating them, the wind filtering and dissipation effects, and the local time dependency. The horizontal wavelengths of the MSTIDs were mostly concentrated between 500 and 800 km, with the mean value of 667 ± 131 km. The observed periods ranged from 30 to 45 min with the mean value of 36 ± 7 min. The observed horizontal phase speeds were distributed around 200 to 400 m/s, with the corresponding mean of 301 ± 75 m/s. The MSTIDs in the winter solstice and equinoctial months preferentially propagated northeastward and northwestward. Meanwhile, during the summer solstice, they propagated in all directions. The anisotropy of the propagation direction might be due to several reasons: the wind and dissipative filtering effects, ion drag effects, the primary source region, and the presence of the secondary or tertiary gravity waves in the thermosphere. Atmospheric gravity waves from strong convective sources might be the primary precursor for the observed equatorial MSTIDs. In all seasons, we noted that the MSTIDs propagating southeastward were probably excited by the likely gravity waves generated by the intertropical convergence zone (ITCZ). Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

18 pages, 11469 KiB  
Article
Evaluation of F10.7, Sunspot Number and Photon Flux Data for Ionosphere TEC Modeling and Prediction Using Machine Learning Techniques
by Andres Gilberto Machado da Silva Benoit and Adriano Petry
Atmosphere 2021, 12(9), 1202; https://doi.org/10.3390/atmos12091202 - 16 Sep 2021
Cited by 6 | Viewed by 2609
Abstract
Considering the growing volumes and varieties of ionosphere data, it is expected that automation of analytical model building using modern technologies could lead to more accurate results. In this work, machine learning techniques are applied to ionospheric modeling and prediction using sun activity [...] Read more.
Considering the growing volumes and varieties of ionosphere data, it is expected that automation of analytical model building using modern technologies could lead to more accurate results. In this work, machine learning techniques are applied to ionospheric modeling and prediction using sun activity data. We propose Total Electron Content (TEC) spectral analysis, using discrete cosine transform (DCT) to evaluate the relation to the solar features F10.7, sunspot number and photon flux data. The ionosphere modeling procedure presented is based on the assessment of a six-year period (2014–2019) of data. Different multi-dimension regression models were considered in experiments, where each geographic location was independently evaluated using its DCT frequency components. The features correlation analysis has shown that 5-year data seem more adequate for training, while learning curves revealed overfitting for polynomial regression from the 4th to 7th degrees. A qualitative evaluation using reconstructed TEC maps indicated that the 3rd degree polynomial regression also seems inadequate. For the remaining models, it can be noted that there is seasonal variation in root-mean-square error (RMSE) clearly related to the equinox (lower error) and solstice (higher error) periods, which points to possible seasonal adjustment in modeling. Elastic Net regularization was also used to reduce global RMSE values down to 2.80 TECU for linear regression. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

73 pages, 46205 KiB  
Article
Towards a Real-Time Description of the Ionosphere: A Comparison between International Reference Ionosphere (IRI) and IRI Real-Time Assimilative Mapping (IRTAM) Models
by Alessio Pignalberi, Marco Pietrella and Michael Pezzopane
Atmosphere 2021, 12(8), 1003; https://doi.org/10.3390/atmos12081003 - 04 Aug 2021
Cited by 9 | Viewed by 2704
Abstract
This paper focuses on a detailed comparison, based on the F2-layer peak characteristics foF2 and hmF2, between the International Reference Ionosphere (IRI), which is a climatological empirical model of the terrestrial ionosphere, and the IRI Real-Time Assimilative Mapping (IRTAM) procedure, which [...] Read more.
This paper focuses on a detailed comparison, based on the F2-layer peak characteristics foF2 and hmF2, between the International Reference Ionosphere (IRI), which is a climatological empirical model of the terrestrial ionosphere, and the IRI Real-Time Assimilative Mapping (IRTAM) procedure, which is a real-time version of IRI based on data assimilation from a global network of ionosondes. To perform such a comparison, two different kinds of datasets have been considered: (1) foF2 and hmF2 as recorded by 40 ground-based ionosondes spread all over the world from 2000 to 2019; (2) foF2 and hmF2 from space-based COSMIC/FORMOSAT-3 radio occultation measurements recorded from 2006 to 2018. The aim of the paper is to understand whether and how much IRTAM improves IRI foF2 and hmF2 outputs for different locations and under different diurnal, seasonal, solar and magnetic activity conditions. The main outcomes of the study are: (1) when ionosonde observations are considered for validation, IRTAM significantly improves the IRI foF2 modeling both in accuracy and precision, while a slight improvement in the IRI hmF2 modeling is observed for specific locations and conditions; (2) when COSMIC observations are considered for validation, no noticeable improvement is observed from the IRTAM side for both foF2 and hmF2. Indeed, IRTAM can improve the IRI foF2 description only nearby the assimilated ionosonde locations, while the IRI hmF2 description is always more accurate and precise than IRTAM one. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

12 pages, 5733 KiB  
Article
Adjusting CCIR Maps to Improve Local Behaviour of Ionospheric Models
by Haris Haralambous, Theodoros Leontiou, Vasilis Petrou, Arun Kumar Singh, Marios Charalambides, Nikos Lithoxopoulos and Agis Agisilaou
Atmosphere 2021, 12(6), 691; https://doi.org/10.3390/atmos12060691 - 28 May 2021
Cited by 5 | Viewed by 2171
Abstract
The objective of this article is to present a concept for single-frequency Global Navigation Satellite System (GNSS) positioning local ionospheric mitigation over a certain area. This concept is based on input parameters driving the NeQuick-G algorithm (the ionospheric single-frequency GNSS correction algorithm adopted [...] Read more.
The objective of this article is to present a concept for single-frequency Global Navigation Satellite System (GNSS) positioning local ionospheric mitigation over a certain area. This concept is based on input parameters driving the NeQuick-G algorithm (the ionospheric single-frequency GNSS correction algorithm adopted by Galileo GNSS system), estimated on a local as opposed to a global scale, from ionospheric characteristics measured by a digital ionosonde and a collocated dual-frequency Total Electron Content (TEC) monitor. This approach facilitates the local adjustment of Committee Consultative for Ionospheric Radiowave propagation (CCIR) files and the Az ionization level, which control the ionospheric electron density profile in NeQuick-G, therefore enabling better estimation of positioning errors under quiet geomagnetic conditions. This novel concept for local ionospheric positioning error mitigation may be adopted at any location where ionospheric characteristics foF2 and M(3000)F2 can be measured, as a means to enhance the accuracy of single-frequency positioning applications based on the NeQuick-G algorithm. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

17 pages, 3686 KiB  
Article
Fluctuation of Lower Ionosphere Associated with Energetic Electron Precipitations during a Substorm
by Tongxing Fu, Zhixu Wu, Peng Hu and Xin Zhang
Atmosphere 2021, 12(5), 573; https://doi.org/10.3390/atmos12050573 - 28 Apr 2021
Cited by 4 | Viewed by 2005
Abstract
In this paper, using the combined observations of the NOAA 16, LANL-01A, IMAGE satellites, VLF radio wave, and ground-based riometers, we study the fluctuation of lower ionosphere-associated precipitating energetic electrons during a geomagnetic storm on 8 November 2004. Associated with the substorm dispersion [...] Read more.
In this paper, using the combined observations of the NOAA 16, LANL-01A, IMAGE satellites, VLF radio wave, and ground-based riometers, we study the fluctuation of lower ionosphere-associated precipitating energetic electrons during a geomagnetic storm on 8 November 2004. Associated with the substorm dispersion injection observed by the LANL-01A satellite, the riometers observed obvious enhancements of ionospheric absorption within the electron isotropic zone, which they attributed to the tail current sheet scattering (TCS) mechanism. Through observations of the NOAA 16 satellite, we found a sharp enhancement of the precipitating electron flux within the anisotropic zone, which entailed an obvious separation of energetic electron precipitation at high latitudes. This energetic electron precipitation within the anisotropic zone leads to the significant enhancement of electron density in the D region, thus resulting in the variations of VLF radio wave amplitudes, which propagate in the middle latitudes. Since the projection of the electron precipitation region within the anisotropic zone is at the inner edge of the plasmapause observed by the IMAGE EUV, the precipitation of energetic electrons should be attributed to the ELF hiss-ring current electron interaction. As a result, the energetic electron precipitations due to the tail current sheet scattering mechanism and wave-particle interaction in the inner magnetosphere were both observed and analyzed as they were associated with a substorm during a geomagnetic storm. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

15 pages, 2946 KiB  
Article
Improvement of Global Ionospheric TEC Derivation with Multi-Source Data in Modip Latitude
by Weizheng Fu, Guanyi Ma, Weijun Lu, Takashi Maruyama, Jinghua Li, Qingtao Wan, Jiangtao Fan and Xiaolan Wang
Atmosphere 2021, 12(4), 434; https://doi.org/10.3390/atmos12040434 - 28 Mar 2021
Cited by 4 | Viewed by 2126
Abstract
Global ionospheric total electron content (TEC) is generally derived with ground-based Global Navigation Satellite System (GNSS) observations based on mathematical models in a solar-geomagnetic reference frame. However, ground-based observations are not well-distributed. There is a lack of observations over sparsely populated areas and [...] Read more.
Global ionospheric total electron content (TEC) is generally derived with ground-based Global Navigation Satellite System (GNSS) observations based on mathematical models in a solar-geomagnetic reference frame. However, ground-based observations are not well-distributed. There is a lack of observations over sparsely populated areas and vast oceans, where the accuracy of TEC derivation is reduced. Additionally, the modified dip (modip) latitude is more suitable than geomagnetic latitude for the ionosphere. This paper investigates the improvement of global TEC with multi-source data and modip latitude, and a simulation with International Reference Ionosphere (IRI) model is developed. Compared with using ground-based observations in geomagnetic latitude, the mean improvement was about 10.88% after the addition of space-based observations and the adoption of modip latitude. Nevertheless, the data from JASON-2 satellite altimetry and COSMIC occultation are sparsely-sampled, which makes the IRI TEC a reasonable estimation for the areas without observation. By using multi-source data from ground-based, satellite-based and IRI-produced observations, global TEC was derived in both geomagnetic and modip latitudes for 12 days of four seasons in 2014 under geomagnetic quiet conditions. The average root-mean-square error (RMSE) of the fitting was reduced by 7.02% in modip latitude. The improvement was largest in March and smallest in June. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

16 pages, 3836 KiB  
Article
Co-Seismic Ionospheric Disturbance with Alaska Strike-Slip Mw7.9 Earthquake on 23 January 2018 Monitored by GPS
by Yongming Zhang, Xin Liu, Jinyun Guo, Kunpeng Shi, Maosheng Zhou and Fangjian Wang
Atmosphere 2021, 12(1), 83; https://doi.org/10.3390/atmos12010083 - 07 Jan 2021
Cited by 8 | Viewed by 2244
Abstract
The Mw7.9 Alaska earthquake at 09:31:40 UTC on 23 January 2018 occurred as the result of strike slip faulting within the shallow lithosphere of the Pacific plate. Global positioning system (GPS) data were used to calculate the slant total electron contents above the [...] Read more.
The Mw7.9 Alaska earthquake at 09:31:40 UTC on 23 January 2018 occurred as the result of strike slip faulting within the shallow lithosphere of the Pacific plate. Global positioning system (GPS) data were used to calculate the slant total electron contents above the epicenter. The singular spectrum analysis (SSA) method was used to extract detailed ionospheric disturbance information, and to monitor the co-seismic ionospheric disturbances (CIDs) of the Alaska earthquake. The results show that the near-field CIDs were detected 8–12 min after the main shock, and the typical compression-rarefaction wave (N-shaped wave) appeared. The ionospheric disturbances propagate to the southwest at a horizontal velocity of 2.61 km/s within 500 km from the epicenter. The maximum amplitude of CIDs appears about 0.16 TECU (1TECU = 1016 el m−2) near the epicenter, and gradually decreases with the location of sub-ionospheric points (SIPs) far away from the epicenter. The attenuation rate of amplitude slows down as the distance between the SIPs and the epicenter increases. The direction of the CIDs caused by strike-slip faults may be affected by the horizontal direction of fault slip. The propagation characteristics of the ionospheric disturbance in the Alaska earthquake may be related to the complex conditions of focal mechanisms and fault location. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
Show Figures

Figure 1

Back to TopTop