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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 (15 March 2023) | Viewed by 17839

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Special Issue Editors

Dr. Alessio Pignalberi

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Guest Editor

UF Osservatori Ionosferici e di Rilevamento Elettromagnetico, Istituto Nazionale di Geofisica e Vulcanologia (INGV), 00143 Rome, Italy
Interests: ionosphere; space weather; empirical models; data-assimilation models; calibration and validation of satellite measurements

Dr. Tommaso Alberti

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Guest Editor

Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome, Italy
Interests: near-earth electromagnetic environment (magnetosphere, ionosphere); extreme events in climate; sea level rise; turbulence in fluids and plasmas; theory of complex systems and chaos
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent years, the monitoring of the ionosphere and near‐Earth environment through satellite measurements has gained increasing importance in the context of Space Weather. Indeed, our society mostly relies on technologies strongly dependent on the properties of the plasma surrounding the Earth. Failures in radars, navigation systems based on Global Navigational Satellite Systems (GNSS), power distribution networks, and the disruption of radio communications, can be directly attributed to Space Weather events triggered by complex phenomena occurring in the ionosphere–magnetosphere–solar wind physical system.

The ever-larger availability of satellite missions probing the properties of the ionospheric plasma provides very valuable measurements to deepen our knowledge of the near‐Earth environment and to develop and improve our models for mitigating Space Weather effects.

This Special Issue aims at studies covering the use of satellite measurements for characterizing the ionosphere and near‐Earth environment plasma conditions with implications on Space Weather applications. Contributions covering, but not restricted to, the following topics are welcomed:

1) Investigation and modeling of the topside ionospheric plasma through in situ measurements on-board Low Earth Orbit (LEO) satellite missions such as ESA Swarm, CSES, C/NOFS, DMSP, and ICON;

2) Calibration and validation of plasma in situ satellite measurements against remote sensing observations from ground-based and space-based instruments and empirical models;

3) Studies on the multiscale properties of the ionosphere through ionospheric indices such as RODI, ROTI, and ROTEI and comparison with empirical ionospheric models;

4) Characterization of the ionospheric plasma under severe Space Weather events, relations with external source mechanisms of magnetospheric and solar wind origin, and impact on the technological systems;

5) Theoretical studies and modeling of the ionospheric plasma dynamics.

Dr. Alessio Pignalberi
Dr. Tommaso Alberti
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

space weather
ionosphere
LEO satellite measurements
plasma density and temperature
ionospheric indices
empirical ionosphere modeling
calibration and validation of satellite measurements
GNSS radio occultation and total electron content

Published Papers (10 papers)

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Research

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28 pages, 5213 KiB

Open AccessArticle

Analyzing the Ionospheric Irregularities Caused by the September 2017 Geomagnetic Storm Using Ground-Based GNSS, Swarm, and FORMOSAT-3/COSMIC Data near the Equatorial Ionization Anomaly in East Africa

by Alireza Atabati, Iraj Jazireeyan, Mahdi Alizadeh, Mahmood Pirooznia, Jakob Flury, Harald Schuh and Benedikt Soja

Remote Sens. 2023, 15(24), 5762; https://doi.org/10.3390/rs15245762 - 17 Dec 2023

Viewed by 830

Abstract

Geomagnetic storms are one of the leading causes of ionospheric irregularities, depending on their intensity. The 6–10 September 2017 geomagnetic storm, the most severe geomagnetic event of the year, resulted from an X9 solar flare and a subsequent coronal mass ejection (CME), with the first sudden storm commencements (SSC) occurring at 23:43 UT on day 06, coinciding with a Sym-H value of approximately 50 nT, triggered by a sudden increase in the solar wind. The interplanetary magnetic field (IMF) and disturbance storm time (Dst) increased when the first SSC occurred at 23:43 UT on 6 September. The second SSC occurred with a more vigorous intensity at 23:00 UT on 7 September, with the Kp index reaching 8 and the auroral electrojet (AE) 2500 nT. In this study, we investigated this phenomenon using data from Swarm, FORMOSAT-3/COSMIC, and ground-based GNSS networks in East Africa to measure ionospheric irregularities near the equatorial ionization anomaly (EIA). In this procedure, the total electron content (TEC), amplitude scintillation (S4), and rate of TEC Index (ROTI) were implemented to recognize ionospheric irregularities appearing during the geomagnetic storm. In addition, the Langmuir plasma probes of the Swarm satellites were employed to identify the rate of electron density index (RODI). The results obtained from the different techniques indicate the effects of geomagnetic storms in terms of increased ionospheric irregularities indicated by geophysical ionospheric parameters. This study demonstrates the potential of using space-based measurements to detect the effects of a geomagnetic storm on ionospheric irregularities for regions where ground-based ionospheric observations are rarely available, such as above the oceans. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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18 pages, 3568 KiB

Open AccessArticle

Statistical Study of the Ionospheric Slab Thickness at Beijing Midlatitude Station

by Yuqiang Zhang, Yong Zhou, Fubin Zhang, Jian Feng, Tong Xu, Zhongxin Deng, Jiawei Zhu, Yi Liu, Xiang Wang, Zhengyu Zhao and Chen Zhou

Remote Sens. 2023, 15(9), 2229; https://doi.org/10.3390/rs15092229 - 23 Apr 2023

Viewed by 1008

Abstract

The ratio of the total electron content (TEC) to the F2-layer peak electron density (NmF2) is known as the ionospheric equivalent slab thickness (EST, also known as τ), and it is a crucial indicator of the ionosphere. Using TEC and NmF2 data from the years 2010 to 2017, this work conducts a comprehensive statistical analysis of the ionospheric slab thickness in Beijing, which is in the midlatitude of East Asia. The outcomes show that the τ have different diurnal variations at different seasons for high/low-solar-activity years. On the whole, daytime τ significantly greater than nighttime τ in summer, and it is the opposite for the τ in winter regardless of the solar cycle, whereas the τ during equinox shows different morphology for high/low-solar-activity years. Specifically, daytime τ is larger than nighttime τ during equinox in years of high-solar activity, while the opposite situation applies for the τ during equinox in years of low-solar activity. Moreover, the pre-sunrise and post-sunset peaks are most pronounced during winter for low-solar-activity years. In summer, there is a great increase in τ during the morning hours when compared with other seasons. Furthermore, the τ decreases with the solar activity during nighttime, whereas it seems there is no correlation between daytime τ and solar activity. This paper explained the primary diurnal variations in τ across different seasons during high-/low-solar-activity years by analyzing relative fluctuations of TEC and NmF2 throughout the corresponding period. In addition, based on the disturbance index (DI), which is calculated by instantaneous τ and its corresponding median, this paper found that the storm-time τ might increase when compared with its median value during the daytime, while it may both increase and decrease during the nighttime, especially around dawn and dusk hours. To further analyze the physical mechanism, an example on 2 October 2013 is also presented. The results indicate that the positive disturbance of τ during the main phase of a geomagnetic storm might be caused by the prompt penetration electric field and neutral wind during the storm, and the τ increases during the early recovery phase might be due to the disturbance dynamo electric field as well as the neutral wind during the storm. Moreover, there is a negative disturbance of τ in the recovery phase during the most disturbed sunrise hours, and it might be due to the electric field reversal, neutral wind or other factors during this period. This paper notes the differences of τ in midlatitude between different longitudinal sectors from the related climatology and storm-time behavior, as it would be helpful to improve the current understanding of τ at midlatitudes in East Asia. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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Graphical abstract

17 pages, 2476 KiB

Open AccessArticle

Validation of Swarm Langmuir Probes by Incoherent Scatter Radars at High Latitudes

by Hayden Fast, Alexander Koustov and Robert Gillies

Remote Sens. 2023, 15(7), 1846; https://doi.org/10.3390/rs15071846 - 30 Mar 2023

Cited by 1 | Viewed by 1009

Abstract

Electron density measured at high latitudes by the Swarm satellites was compared with measurements by the incoherent scatter radars at Resolute Bay and Poker Flat. Overall, the ratio of Swarm-based electron density to that measured by the radars was about 0.5–0.6. Smaller ratios were observed at larger electron densities, usually during the daytime. At low electron densities less than 3 × 10¹⁰ m⁻³, the ratios were typically above 1, indicating an overestimation effect. The overestimation effect was stronger at night and for Swarm B. It was more evident at lower solar activity when the electron densities in the topside ionosphere were lower. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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Graphical abstract

11 pages, 6277 KiB

Open AccessCommunication

Travelling Ionospheric Disturbance Direction of Propagation Detection Using Swarm A-C In-Situ Electron Density

by Haris Haralambous and Krishnendu Sekhar Paul

Remote Sens. 2023, 15(4), 897; https://doi.org/10.3390/rs15040897 - 06 Feb 2023

Cited by 3 | Viewed by 1178

Abstract

We demonstrate a simple method to estimate the direction of propagation of travelling ionospheric disturbances using in-situ electron density measurements in the topside ionosphere by exploiting the side-by-side flying configuration of Swarm A and C satellites. Corresponding cases of TIDs recorded on detrended GPS total electron content (TEC) maps over different continents are used to validate this approach. This simple method could be suitable to detect the direction of propagation of TID wavefronts over the ocean and the polar regions where ground-based GNSS stations are unavailable. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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21 pages, 9738 KiB

Open AccessArticle

Parallel Electrical Conductivity at Low and Middle Latitudes in the Topside Ionosphere Derived from CSES-01 Measurements

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

Remote Sens. 2022, 14(20), 5079; https://doi.org/10.3390/rs14205079 - 11 Oct 2022

Viewed by 1288

Abstract

The study of electrical currents in the topside ionosphere is of great importance, as it may allow a better understanding of the processes involved in the Sun–Earth interaction and magnetosphere–ionosphere–thermosphere coupling, two crucial aspects debated by the Space Weather scientific community. In this context, investigating the electrical conductivity parallel to the geomagnetic field in the topside ionosphere is of primary importance because: (1) it provides information on the capability of the ionosphere to conduct currents; (2) it relates current density and electric field through Ohm’s law; (3) it can help to quantify the dissipation of currents; (4) it is generally modeled and not locally measured by in situ missions. In this work, we used in situ measurements of electron density and temperature recorded between 2019 and 2021 by the China Seismo-Electromagnetic Satellite (CSES-01) flying with an orbital inclination of 97.4° and at an altitude of about 500 km to compute the parallel electrical conductivity in the topside ionosphere at low and middle latitudes at the two fixed local times (LT) characterizing the CSES-01 mission: around 02 and 14 LT. The results, which are discussed in light of previous literature, highlight the dependence of conductivity on latitude and longitude and are compared with those obtained using values both measured by the Swarm B satellite (flying at a similar altitude) and modeled by the International Reference Ionosphere in the same time period. In particular, we found a diurnal variation in parallel electrical conductivity, with a slight hemispheric asymmetry. Daytime features are compatible with Sq and equatorial electrojet current systems, containing “anomalous” low values of conductivity in correspondence with the South Atlantic region that could be physical in nature. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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22 pages, 5128 KiB

Open AccessArticle

Inter-Calibration and Statistical Validation of Topside Ionosphere Electron Density Observations Made by CSES-01 Mission

by Alessio Pignalberi, Michael Pezzopane, Igino Coco, Mirko Piersanti, Fabio Giannattasio, Paola De Michelis, Roberta Tozzi and Giuseppe Consolini

Remote Sens. 2022, 14(18), 4679; https://doi.org/10.3390/rs14184679 - 19 Sep 2022

Cited by 8 | Viewed by 1661

Abstract

The China Seismo-Electromagnetic Satellite (CSES-01) provides in situ electron density (Ne) observations through Langmuir probes (LPs) in the topside ionosphere since February 2018. CSES-01 is a sun-synchronous satellite probing the ionosphere around two fixed local times (LTs), 14 LT in the daytime sector and 02 LT in the night-time sector, at an altitude of about 500 km. Previous studies evidenced that CSES-01 seems to underestimate Ne measurements with respect to those acquired by similar satellites or obtained from different instruments. To overcome this issue, we calibrated CSES-01 LP Ne observations through Swarm B satellite data, which flies approximately at CSES-01 altitude. As a first step, Swarm B LP Ne observations were calibrated through Faceplate (FP) Ne observations from the same satellite. Such calibration allowed solving the Ne overestimation made by Swarm LP during nighttime for low solar activity. Then, the calibrated Swarm B LP Ne observations were used to calibrate CSES-01 Ne observations on a statistical basis. Finally, the goodness of the proposed calibration procedure was statistically assessed through a comparison with Ne observations by incoherent scatter radars (ISRs) located at Jicamarca, Arecibo, and Millstone Hill. The proposed calibration procedure allowed solving the CSES-01 Ne underestimation issue for both daytime and nighttime sectors and brought CSES-01 Ne observations in agreement with corresponding ones measured by Swarm B, ISRs, and with those modelled by the International Reference Ionosphere (IRI). This is a first fundamental step towards a possible future inclusion of CSES-01 Ne observations in the dataset underlying IRI for the purpose of improving the description of the topside ionosphere made by IRI. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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26 pages, 4860 KiB

Open AccessArticle

Signatures of Equatorial Plasma Bubbles and Ionospheric Scintillations from Magnetometer and GNSS Observations in the Indian Longitudes during the Space Weather Events of Early September 2017

by Ram Kumar Vankadara, Sampad Kumar Panda, Christine Amory-Mazaudier, Rolland Fleury, Venkata Ratnam Devanaboyina, Tarun Kumar Pant, Punyawi Jamjareegulgarn, Mohd Anul Haq, Daniel Okoh and Gopi Krishna Seemala

Remote Sens. 2022, 14(3), 652; https://doi.org/10.3390/rs14030652 - 29 Jan 2022

Cited by 28 | Viewed by 3601

Abstract

Scintillation due to ionospheric plasma irregularities remains a challenging task for the space science community as it can severely threaten the dynamic systems relying on space-based navigation services. In the present paper, we probe the ionospheric current and plasma irregularity characteristics from a latitudinal arrangement of magnetometers and Global Navigation Satellite System (GNSS) stations from the equator to the far low latitude location over the Indian longitudes, during the severe space weather events of 6–10 September 2017 that are associated with the strongest and consecutive solar flares in the 24th solar cycle. The night-time influence of partial ring current signatures in ASYH and the daytime influence of the disturbances in the ionospheric E region electric currents (D_iono) are highlighted during the event. The total electron content (TEC) from the latitudinal GNSS observables indicate a perturbed equatorial ionization anomaly (EIA) condition on 7 September, due to a sequence of M-class solar flares and associated prompt penetration electric fields (PPEFs), whereas the suppressed EIA on 8 September with an inverted equatorial electrojet (EEJ) suggests the driving disturbance dynamo electric current (Ddyn) corresponding to disturbance dynamo electric fields (DDEFs) penetration in the E region and additional contributions from the plausible storm-time compositional changes (O/N2) in the F-region. The concurrent analysis of the D_iono and EEJ strengths help in identifying the pre-reversal effect (PRE) condition to seed the development of equatorial plasma bubbles (EPBs) during the local evening sector on the storm day. The severity of ionospheric irregularities at different latitudes is revealed from the occurrence rate of the rate of change of TEC index (ROTI) variations. Further, the investigations of the hourly maximum absolute error (MAE) and root mean square error (RMSE) of ROTI from the reference quiet days’ levels and the timestamps of ROTI peak magnitudes substantiate the severity, latitudinal time lag in the peak of irregularity, and poleward expansion of EPBs and associated scintillations. The key findings from this study strengthen the understanding of evolution and the drifting characteristics of plasma irregularities over the Indian low latitudes. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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15 pages, 12331 KiB

Open AccessTechnical Note

A Proposal for Modification of Plasmaspheric Electron Density Profiles Using Characteristics of Lightning Whistlers

by Desy Purnami Singgih Putri, Yoshiya Kasahara, Mamoru Ota, Shoya Matsuda, Fuminori Tsuchiya, Atsushi Kumamoto, Ayako Matsuoka and Yoshizumi Miyoshi

Remote Sens. 2023, 15(5), 1306; https://doi.org/10.3390/rs15051306 - 26 Feb 2023

Cited by 1 | Viewed by 1264

Abstract

Reconstruction of reliable plasmaspheric electron density profiles is important for understanding physical processes in the plasmasphere. This paper proposes a technique that can be applied to correct the plasmaspheric electron density profiles using ray tracing by scrutinizing dispersion analyses of lightning whistlers. The Global Core Plasma Model and the International Reference Ionosphere were introduced as a reference electron density profile. Modifications of this electron density profile were then proposed to satisfy the dispersion characteristics of lightning whistlers measured by satellites in the plasmasphere. We first introduce two kinds of functions to modify the electron density: constant and linear, the linear function is more adequate. We applied our method to two lightning whistler events on 14 August 2017, measured by the Plasma Wave Experiment/Waveform Capture aboard the Arase satellite, and analyzed the dispersion of the observed lightning whistlers. We show how the density modification affects the delay time of the ray path and satisfies the dispersion characteristics under the appropriate adjustments. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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22 pages, 1330 KiB

Open AccessTechnical Note

The CAESAR Project for the ASI Space Weather Infrastructure

by M. Laurenza, D. Del Moro, T. Alberti, R. Battiston, S. Benella, F. Benvenuto, F. Berrilli, I. Bertello, B. Bertucci, L. Biasiotti, C. Campi, V. Carbone, M. Casolino, C. Cecchi Pestellini, F. Chiappetta, I. Coco, S. Colombo, G. Consolini, R. D’Amicis, G. De Gasperis, R. De Marco, A. Del Corpo, P. Diego, V. Di Felice, L. Di Fino, C. Di Geronimo, F. Faldi, F. Ferrente, C. Feruglio, E. Fiandrini, F. Fiore, R. Foldes, V. Formato, G. Francisco, F. Giannattasio, M. Giardino, P. Giobbi, L. Giovannelli, M. Giusti, A. Gorgi, B. Heilig, G. Iafrate, S. L. Ivanovski, G. Jerse, M. B. Korsos, F. Lepreti, D. Locci, C. Magnafico, V. Mangano, M. F. Marcucci, M. Martucci, S. Massetti, G. Micela, A. Milillo, R. Miteva, M. Molinaro, R. Mugatwala, A. Mura, G. Napoletano, L. Narici, C. Neubüser, G. Nisticò, M. Pauluzzi, A. Perfetti, S. Perri, A. Petralia, M. Pezzopane, M. Piersanti, E. Pietropaolo, A. Pignalberi, C. Plainaki, G. Polenta, L. Primavera, G. Romoli, M. Rossi, L. Santarelli, G. Santi Amantini, F. Siciliano, G. Sindoni, S. Spadoni, R. Sparvoli, M. Stumpo, N. Tomassetti, R. Tozzi, V. Vagelli, N. Vasantharaju, A. Vecchio, M. Vellante, S. Vernetto, C. Vigorito, M. J. West, G. Zimbardo, P. Zucca, F. Zuccarello and P. Zuccon Show full author list Hide full author list

Remote Sens. 2023, 15(2), 346; https://doi.org/10.3390/rs15020346 - 06 Jan 2023

Cited by 2 | Viewed by 2495

Abstract

This paper presents the project Comprehensive spAce wEather Studies for the ASPIS prototype Realization (CAESAR), which aims to tackle the relevant aspects of Space Weather (SWE) science and develop a prototype of the scientific data centre for Space Weather of the Italian Space Agency (ASI) called ASPIS (ASI SPace Weather InfraStructure). To this end, CAESAR involves the majority of the SWE Italian community, bringing together 10 Italian institutions as partners, and a total of 92 researchers. The CAESAR approach encompasses the whole chain of phenomena from the Sun to Earth up to planetary environments in a multidisciplinary, comprehensive, and unprecedented way. Detailed and integrated studies are being performed on a number of well-observed “target SWE events”, which exhibit noticeable SWE characteristics from several SWE perspectives. CAESAR investigations synergistically exploit a great variety of different products (datasets, codes, models), both long-standing and novel, that will be made available in the ASPIS prototype: this will consist of a relational database (DB), an interface, and a wiki-like documentation structure. The DB will be accessed through both a Web graphical interface and the ASPIS.py module, i.e., a library of functions in Python, which will be available for download and installation. The ASPIS prototype will unify multiple SWE resources through a flexible and adaptable architecture, and will integrate currently available international SWE assets to foster scientific studies and advance forecasting capabilities. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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13 pages, 2467 KiB

Open AccessTechnical Note

Modeling Post-Sunset Equatorial Spread-F Occurrence as a Function of Evening Upward Plasma Drift Using Logistic Regression, Deduced from Ionosondes in Southeast Asia

by Prayitno Abadi, Umar Ali Ahmad, Yuichi Otsuka, Punyawi Jamjareegulgarn, Dyah Rahayu Martiningrum, Agri Faturahman, Septi Perwitasari, Randy Erfa Saputra and Reza Rendian Septiawan

Remote Sens. 2022, 14(8), 1896; https://doi.org/10.3390/rs14081896 - 14 Apr 2022

Cited by 8 | Viewed by 1892

Abstract

The occurrence of post-sunset equatorial spread-F (ESF) could have detrimental effects on trans-ionospheric radio wave propagation used in modern communications systems. This problem calls for a simple but robust model that accurately predicts the occurrence of post-sunset ESF. Logistic regression was implemented to [...] Read more.

\hat{y} = 1 / [1 + \exp (- z)]

, where

\hat{y}

represents the probability of post-sunset ESF occurrence, and

z

is a linear function containing

v

. The value of

v

is derived from the vertical motion of the bottom side of the F-region in the evening equatorial ionosphere, which is observed by the ionosondes in Southeast Asia. Data points (938) of v and post-sunset ESF occurrence were collected in the equinox seasons from 2003 to 2016. The training set used 70% of the dataset to derive

z

and

\hat{y}

and the remaining 30% was used to test the performance of

\hat{y}

. The expression

z = - 2.25 + 0.14 v

was obtained from the training set, and

\hat{y} \geq 0.5

(v ≥ ~16.1 m/s) and

\hat{y} < 0.5

(v < ~16.1 m/s) represented the occurrence and non-occurrence of ESF, respectively, with an accuracy of ~0.8 and a true skill score (TSS) of ~0.6. Similarly, in the testing set,

\hat{y}

shows an accuracy of ~0.8 and a TSS of ~0.6. Further analysis suggested that the performance of the z-function can be reliable in the daily F_10.7 levels ranging from 60 to 140 solar flux units. The z-function implemented in the logistic regression (

\hat{y}

) found in this study is a novel technique to predict the post-sunset ESF occurrence. The performance consistency between the training set and the testing set concludes that the z-function and the

\hat{y}

values of the proposed model could be a simple and robust mathematical model for daily nowcasting the occurrence or non-occurrence of post-sunset ESFs. Full article

(This article belongs to the Special Issue Satellite Measurements and the Monitoring of Ionosphere and Space Weather)

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