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Universe
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Planetary Plasma Environment
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Planetary Plasma Environment

A special issue of Universe (ISSN 2218-1997). This special issue belongs to the section "Space Science".

Deadline for manuscript submissions: closed (20 August 2022) | Viewed by 9654

Special Issue Editor

Dr. František Němec

E-Mail Website
Guest Editor
Space Physics Group, Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic
Interests: space plasma physics; solar-terrestrial physics; inner magnetosphere; plasma waves; radiation belts

Special Issue Information

Dear Colleagues,

Solar wind interaction with planetary objects in the solar system generally results in a formation of two distinct boundaries upstream the obstacle, called magnetopause (or, in the case of unmagnetized planets, rather magnetic pileup boundary) and bow shock. In the first approximation, the solar wind plasma has no access to radial distances lower than the magnetopause standoff distance, and an (induced) magnetosphere is formed. The focus of this Special Issue is the magnetospheric plasma environment around the solar system’s planetary objects. At lower altitudes, this includes the planetary ionospheres and various factors responsible for their variability, including energetic particle precipitation. Various electromagnetic wave phenomena taking place in the respective magnetospheres are also of interest, as these can ultimately be responsible for the particle energization and/or loss. At larger radial distances, the topic includes the energy coupling between solar wind and the magnetospheres, as well as studies related to the features of and the balance across distinct plasma boundaries. Theoretical and model contributions, as well as observational studies using data from both older and recent satellite missions and ground-based instruments, are envisaged.

Dr. František Němec
Guest Editor

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. Universe is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. 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

  • Magnetosphere
  • Plasmasphere
  • Ionosphere

Published Papers (6 papers)

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Research

15 pages, 3542 KiB  
Article
Ionospheric TEC Forecasting over an Indian Low Latitude Location Using Long Short-Term Memory (LSTM) Deep Learning Network
by Kanaka Durga Reddybattula, Likhita Sai Nelapudi, Mefe Moses, Venkata Ratnam Devanaboyina, Masood Ashraf Ali, Punyawi Jamjareegulgarn and Sampad Kumar Panda
Universe 2022, 8(11), 562; https://doi.org/10.3390/universe8110562 - 27 Oct 2022
Cited by 16 | Viewed by 1826
Abstract
The forecasting of ionospheric electron density has been of great interest to the research scientists and engineers’ community as it significantly influences satellite-based navigation, positioning, and communication applications under the influence of space weather. Hence, the present paper adopts a long short-term memory [...] Read more.
The forecasting of ionospheric electron density has been of great interest to the research scientists and engineers’ community as it significantly influences satellite-based navigation, positioning, and communication applications under the influence of space weather. Hence, the present paper adopts a long short-term memory (LSTM) deep learning network model to forecast the ionospheric total electron content (TEC) by exploiting global positioning system (GPS) observables, at a low latitude Indian location in Bangalore (IISC; Geographic 13.03° N and 77.57° E), during the 24th solar cycle. The proposed model uses about eight years of GPS-TEC data (from 2009 to 2017) for training and validation, whereas the data for 2018 was used for independent testing and forecasting of TEC. Apart from the input TEC parameters, the model considers sequential data of solar and geophysical indices to realize the effects. The performance of the model is evaluated by comparing the forecasted TEC values with the observed and global empirical ionosphere model (international reference ionosphere; IRI-2016) through a set of validation metrics. The analysis of the results during the test period showed that LSTM output closely followed the observed GPS-TEC data with a relatively minimal root mean square error (RMSE) of 1.6149 and the highest correlation coefficient (CC) of 0.992, as compared to IRI-2016. Furthermore, the day-to-day performance of LSTM was validated during the year 2018, inferring that the proposed model outcomes are significantly better than IRI-2016 at the considered location. Implementation of the model at other latitudinal locations of the region is suggested for an efficient regional forecast of TEC across the Indian region. The present work complements efforts towards establishing an efficient regional forecasting system for indices of ionospheric delays and irregularities, which are responsible for degrading static, as well as dynamic, space-based navigation system performances. Full article
(This article belongs to the Special Issue Planetary Plasma Environment)
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11 pages, 1598 KiB  
Article
The Validation of FORMOSAT-3/COSMIC Measurements in the Middle Latitude Region of China with Ionosonde Observations during 2015–2018
by Liangchen Hu, Fanfan Su, Fuying Zhu and Xinxing Li
Universe 2022, 8(10), 528; https://doi.org/10.3390/universe8100528 - 11 Oct 2022
Viewed by 790
Abstract
We used ground-based ionosonde observations at Ganzi (31.2° N, 100.4° E) to validate the COSMIC measurement in the middle latitude region of China during low solar activity. First, eligible data pairs from two kinds of techniques were selected for the validation. Then, we [...] Read more.
We used ground-based ionosonde observations at Ganzi (31.2° N, 100.4° E) to validate the COSMIC measurement in the middle latitude region of China during low solar activity. First, eligible data pairs from two kinds of techniques were selected for the validation. Then, we investigated the consistency of the ionospheric parameters’ F layer peak density (NmF2) from selected data pairs at different local times in different seasons, and we also investigated the F layer peak height (hmF2). The correlation of the parameters (including NmF2 and hmF2) were good in general. The correlation coefficients of the NmF2 and hmF2 from all selected data pairs were 0.94 and 0.77, respectively. The correlation coefficients were higher in the daytime than those at night for both the NmF2 and hmF2. The correlation coefficients in different seasons were close to each other for both the NmF2 and hmF2. The NmF2 from the COSMIC tends to be overestimated during the whole day except in the morning; the hmF2 from the COSMIC tends to be overestimated in the morning and underestimated in the afternoon. Full article
(This article belongs to the Special Issue Planetary Plasma Environment)
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8 pages, 629 KiB  
Communication
Modeling of Magnetospheres of Terrestrial Exoplanets in the Habitable Zone around G-Type Stars
by Elena S. Belenkaya, Igor I. Alexeev and Marina S. Blokhina
Universe 2022, 8(4), 231; https://doi.org/10.3390/universe8040231 - 08 Apr 2022
Cited by 1 | Viewed by 1604
Abstract
Using a paraboloid model of an Earth-like exoplanetary magnetospheric magnetic field, developed from a model of the Earth, we investigate the magnetospheric structure of planets located in the habitable zone around G-type stars. Different directions of the stellar wind magnetic field are considered [...] Read more.
Using a paraboloid model of an Earth-like exoplanetary magnetospheric magnetic field, developed from a model of the Earth, we investigate the magnetospheric structure of planets located in the habitable zone around G-type stars. Different directions of the stellar wind magnetic field are considered and the corresponding variations in the magnetospheric structure are obtained. It is shown that the exoplanetary environment significantly depends on stellar wind magnetic field orientation and that the parameters of magnetospheric current systems depend on the distance to the stand-off magnetopause point. Full article
(This article belongs to the Special Issue Planetary Plasma Environment)
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13 pages, 2613 KiB  
Communication
Ionospheric Response along Meridian for the Certain Storm Using TEC and foF2
by Olga Maltseva, Artem Kharakhashyan and Tatyana Nikitenko
Universe 2021, 7(9), 342; https://doi.org/10.3390/universe7090342 - 11 Sep 2021
Cited by 3 | Viewed by 1445
Abstract
For a long time, the equivalent ionospheric slab thickness τ has remained in the shadow of ionospheric main parameters: the maximum density, NmF2 (or the critical frequency, foF2), and the total electron content. Empirical global models have been developed for these two parameters. [...] Read more.
For a long time, the equivalent ionospheric slab thickness τ has remained in the shadow of ionospheric main parameters: the maximum density, NmF2 (or the critical frequency, foF2), and the total electron content. Empirical global models have been developed for these two parameters. Recently, several global models of τ have appeared concurrently. This paper compares τ of the Neustrelitz equivalent slab thickness model (NSTM), with τ(IRI-Plas) of the IRI-Plas model, and τ(Appr) of the approximation model, constructed along the 30° E meridian using data from several ionosondes. The choice of the model of the best conformity with observational data was made, which was used to study the effects of space weather during several magnetic storms in March 2012. The effects included: (1) a transition from negative disturbances at high latitudes to positive ones at low latitudes, (2) the super-fountain effect, which had been revealed and explained in previous papers, (3) a deepening of the main ionospheric trough. The efficiency of using τ(Appr) and τ(IRI-Plas) models for studying the effects of space weather has been confirmed. The advantage of the τ(Appr) model is its closeness to real data. The advantage of the τ(IRI-Plas) model is the ability to determine foF2 without ionosondes. The efficiency of the NSTM model is insufficient for a role of a global τ model due to the accuracy decreasing with the increasing latitude. Full article
(This article belongs to the Special Issue Planetary Plasma Environment)
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12 pages, 2035 KiB  
Article
Evaluating the Accuracy of Magnetospheric Magnetic Field Models Using Cluster Spacecraft Magnetic Field Measurements
by František Němec and Marie Kotková
Universe 2021, 7(8), 282; https://doi.org/10.3390/universe7080282 - 03 Aug 2021
Cited by 2 | Viewed by 1368
Abstract
Magnetic fields in the inner magnetosphere can be obtained as vector sums of the Earth’s own internal magnetic field and magnetic fields stemming from currents flowing in the space plasma. While the Earth’s internal magnetic field is accurately described by the International Geomagnetic [...] Read more.
Magnetic fields in the inner magnetosphere can be obtained as vector sums of the Earth’s own internal magnetic field and magnetic fields stemming from currents flowing in the space plasma. While the Earth’s internal magnetic field is accurately described by the International Geomagnetic Reference Field (IGRF) model, the characterization of the external magnetic fields is significantly more complicated, as they are highly variable and dependent on the actual level of the geomagnetic activity. Tsyganenko family magnetic field models (T89, T96, T01, TA15B, TA15N), parameterized by the geomagnetic activity level and solar wind parameters, are often used by the involved community to describe these fields. In the present paper, we use a large dataset (2001–2018) of magnetospheric magnetic field measurements obtained by the four Cluster spacecraft to assess the accuracy of these models. We show that, while the newer models (T01, TA15B, TA15N) perform significantly better than the old ones (T89, T96), there remain some systematic deviations, in particular at larger latitudes. Moreover, we compare the locations of the min-B equator determined using the four-point Cluster spacecraft measurements with the locations determined using the magnetic field models. We demonstrate that, despite the newer models being comparatively slightly more accurate, an uncertainty of about one degree in the latitude of the min-B equator remains. Full article
(This article belongs to the Special Issue Planetary Plasma Environment)
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12 pages, 17728 KiB  
Article
Variations in Energetic Particle Fluxes around Significant Geomagnetic Storms Observed by the Low-Altitude DEMETER Spacecraft
by Stefan Gohl, František Němec and Michel Parrot
Universe 2021, 7(8), 260; https://doi.org/10.3390/universe7080260 - 23 Jul 2021
Viewed by 1328
Abstract
A superposed epoch analysis is conducted for five geomagnetic storms in the years 2005 and 2006 with the aim to understand energetic particle flux variations as a function of L-shell, energy and time from the Dst minimum. Data measured by the low-altitude DEMETER [...] Read more.
A superposed epoch analysis is conducted for five geomagnetic storms in the years 2005 and 2006 with the aim to understand energetic particle flux variations as a function of L-shell, energy and time from the Dst minimum. Data measured by the low-altitude DEMETER spacecraft were used for this purpose. The storms were identified by a Dst index below −100 nT, as well as their being isolated events in a seven-day time window. It is shown that they can be categorized into two types. The first type shows significant variations in the energetic particle fluxes around the Dst minimum and increased fluxes at high energies (>1.5 MeV), while the second type only shows increased fluxes around the Dst minimum without the increased fluxes at high energies. The first type of storm is related to more drastic but shorter-lasting changes in the solar wind parameters than the second type. One storm does not fit either category, exhibiting features from both storm types. Additionally, we investigate whether the impenetrable barrier for ultra-relativistic electrons also holds in extreme geomagnetic conditions. For the highest analyzed energies, the obtained barrier L-shells do not go below 2.6, consistent with previous findings. Full article
(This article belongs to the Special Issue Planetary Plasma Environment)
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