Articles | Volume 37, issue 5
https://doi.org/10.5194/angeo-37-807-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/angeo-37-807-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
17 Sep 2019
Regular paper |
| 17 Sep 2019
| 17 Sep 2019
On developing a new ionospheric plasma index for Brazilian equatorial F region irregularities
Laysa Cristina Araujo Resende
CORRESPONDING AUTHOR
National Institute for Space Research (INPE), São José dos Campos,
SP, Brazil
National Space Science Center, Chinese Academy of Sciences (CAS), Beijing,
China
Clezio Marcos Denardini
National Institute for Space Research (INPE), São José dos Campos,
SP, Brazil
Giorgio Arlan Silva Picanço
National Institute for Space Research (INPE), São José dos Campos,
SP, Brazil
Juliano Moro
National Space Science Center, Chinese Academy of Sciences (CAS), Beijing,
China
Southern Regional Space Research Center (CRS/INPE), Santa Maria, RS, Brazil
Diego Barros
National Institute for Space Research (INPE), São José dos Campos,
SP, Brazil
Cosme Alexandre Oliveira Barros Figueiredo
National Institute for Space Research (INPE), São José dos Campos,
SP, Brazil
Régia Pereira Silva
National Institute for Space Research (INPE), São José dos Campos,
SP, Brazil
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Pedro Alves Fontes, Marcio Tadeu de Assis Honorato Muella, Laysa Cristina Araújo Resende, Vânia Fátima Andrioli, Paulo Roberto Fagundes, Valdir Gil Pillat, Paulo Prado Batista, and Alexander Jose Carrasco
Ann. Geophys., 41, 209–224, https://doi.org/10.5194/angeo-41-209-2023, https://doi.org/10.5194/angeo-41-209-2023, 2023
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In the terrestrial ionosphere, sporadic (metallic) layers are formed. The formation of these layers are related to the action of atmospheric waves. These waves, also named tides, are due to the absorption of solar radiation in the atmosphere. We investigated the role of the tides with 8 h period in the formation of the sporadic layers. The study was conducted using ionosonde and meteor radar data, as well as computing simulations. The 8 h tides intensified the density of the sporadic layers.
Giorgio Arlan Silva Picanço, Clezio Marcos Denardini, Paulo Alexandre Bronzato Nogueira, Laysa Cristina Araujo Resende, Carolina Sousa Carmo, Sony Su Chen, Paulo França Barbosa-Neto, and Esmeralda Romero-Hernandez
Ann. Geophys., 40, 503–517, https://doi.org/10.5194/angeo-40-503-2022, https://doi.org/10.5194/angeo-40-503-2022, 2022
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In this work, we use the Disturbance Ionosphere indeX (DIX) to study equatorial plasma bubble (EPB) events over the Brazilian equatorial and low latitudes. Our results showed that the DIX detected EPB disturbances in terms of their intensity and occurrence times. Therefore, these responses agreed with the ionosphere behavior before, during, and after the studied EPBs. Finally, these disturbances tended to be higher (lower) in high (low) solar activity.
Laysa C. A. Resende, Yajun Zhu, Clezio M. Denardini, Sony S. Chen, Ronan A. J. Chagas, Lígia A. Da Silva, Carolina S. Carmo, Juliano Moro, Diego Barros, Paulo A. B. Nogueira, José P. Marchezi, Giorgio A. S. Picanço, Paulo Jauer, Régia P. Silva, Douglas Silva, José A. Carrasco, Chi Wang, and Zhengkuan Liu
Ann. Geophys., 40, 191–203, https://doi.org/10.5194/angeo-40-191-2022, https://doi.org/10.5194/angeo-40-191-2022, 2022
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This study showed the ionospheric response over low-latitude regions in Brazil predicted by Martínez-Ledesma et al. (2020) for the solar eclipse event on 14 December 2020. We used a multi-instrumental and modeling analysis to observe the modifications in the E and F regions and the Es layers over Campo Grande and Cachoeira Paulista. The results showed that solar eclipses can cause significant ionosphere modifications even though they only partially reach the Brazilian low-latitude regions.
Juliano Moro, Jiyao Xu, Clezio Marcos Denardini, Laysa Cristina Araújo Resende, Régia Pereira Silva, Sony Su Chen, Giorgio Arlan da Silva Picanço, Liu Zhengkuan, Hui Li, Chunxiao Yan, Chi Wang, and Nelson Jorge Schuch
Ann. Geophys., 38, 457–466, https://doi.org/10.5194/angeo-38-457-2020, https://doi.org/10.5194/angeo-38-457-2020, 2020
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The monthly averages of the F2 critical frequency (foF2), its peak height (hmF2), and the E-region critical frequency (foE) acquired by the DPS4-D installed in Santa Maria, Brazil, is compared to the International Reference Ionosphere (IRI-2016) model predictions. It is important to test the performance of the IRI over Santa Maria because it is located in the SAMA, which is a region particularly important for high-frequency (HF) ground-to-satellite navigation signals.
Regia Pereira da Silva, Clezio Marcos Denardini, Manilo Soares Marques, Laysa Cristina Araujo Resende, Juliano Moro, Giorgio Arlan da Silva Picanço, Gilvan Luiz Borba, and Marcos Aurelio Ferreira dos Santos
Ann. Geophys., 38, 27–34, https://doi.org/10.5194/angeo-38-27-2020, https://doi.org/10.5194/angeo-38-27-2020, 2020
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In this work, we studied the HILDCAA disturbance time effects in the TEC by analyzing local time and seasonal dependences, and the influences of the solar wind velocity on a sample of 10 intervals occurring in 2015 and 2016. The main results show great variability in the hourly distribution of the dTEC between one interval and another, seasonal behavior different from that presented by geomagnetic storms, and interestingly no relation between the dTEC disturbances and the magnitude of the HSS.
Laysa C. A. Resende, Christina Arras, Inez S. Batista, Clezio M. Denardini, Thainá O. Bertollotto, and Juliano Moro
Ann. Geophys., 36, 587–593, https://doi.org/10.5194/angeo-36-587-2018, https://doi.org/10.5194/angeo-36-587-2018, 2018
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We present new results on the behavior of sporadic E layers (Es layers) using GPS (global positioning system) radio occultation (RO) measurements obtained from the FORMOSAT-3/COSMIC satellites and digisonde data over Cachoeira Paulista, a low-latitude station in Brazil.
Cristiano M. Wrasse, Prosper K. Nyassor, Ligia A. da Silva, Cosme O. A. B. Figueiredo, José V. Bageston, Kleber P. Naccarato, Diego Barros, Hisao Takahashi, and Delano Gobbi
EGUsphere, https://doi.org/10.5194/egusphere-2023-1825, https://doi.org/10.5194/egusphere-2023-1825, 2023
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This present work investigates the propagation dynamics and the sources-source mechanisms of quasi-monochromatic gravity waves (QMGWs) observed between April, 2017 and April, 2022 at São Martinho da Serra. The QMGW parameters were estimated using a 2D spectral analysis, and their source locations were identified using a backward ray tracing model. Furthermore, the propagation conditions, sources, and source mechanisms of the QMGWs were extensively studied.
Pedro Alves Fontes, Marcio Tadeu de Assis Honorato Muella, Laysa Cristina Araújo Resende, Vânia Fátima Andrioli, Paulo Roberto Fagundes, Valdir Gil Pillat, Paulo Prado Batista, and Alexander Jose Carrasco
Ann. Geophys., 41, 209–224, https://doi.org/10.5194/angeo-41-209-2023, https://doi.org/10.5194/angeo-41-209-2023, 2023
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In the terrestrial ionosphere, sporadic (metallic) layers are formed. The formation of these layers are related to the action of atmospheric waves. These waves, also named tides, are due to the absorption of solar radiation in the atmosphere. We investigated the role of the tides with 8 h period in the formation of the sporadic layers. The study was conducted using ionosonde and meteor radar data, as well as computing simulations. The 8 h tides intensified the density of the sporadic layers.
Hisao Takahashi, Cosme A. O. B. Figueiredo, Patrick Essien, Cristiano M. Wrasse, Diego Barros, Prosper K. Nyassor, Igo Paulino, Fabio Egito, Geangelo M. Rosa, and Antonio H. R. Sampaio
Ann. Geophys., 40, 665–672, https://doi.org/10.5194/angeo-40-665-2022, https://doi.org/10.5194/angeo-40-665-2022, 2022
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We observed two different wave propagations in the earth’s upper atmosphere: a gravity wave in the mesosphere and the ionospheric disturbances. We investigated the wave propagations by using airglow imaging techniques. It is found that there was a gravity wave generation from the tropospheric convection spot, and it propagated upward in the ionosphere. This reports observational evidence of gravity wave propagation from the troposphere to ionosphere.
Prosper K. Nyassor, Cristiano M. Wrasse, Igo Paulino, Eliah F. M. T. São Sabbas, José V. Bageston, Kleber P. Naccarato, Delano Gobbi, Cosme A. O. B. Figueiredo, Toyese T. Ayorinde, Hisao Takahashi, and Diego Barros
Atmos. Chem. Phys., 22, 15153–15177, https://doi.org/10.5194/acp-22-15153-2022, https://doi.org/10.5194/acp-22-15153-2022, 2022
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This work investigates the sources of concentric gravity waves (CGWs) excited by a moving system of clouds with several overshooting regions on 1–2 October 2019 at São Martinho da Serra. The parameters of these waves were estimated using 2D spectral analysis and their source locations identified using backward ray tracing. Furthermore, the sources of these waves were properly identified by tracking the individual overshooting regions in space and time since the system of clouds was moving.
Giorgio Arlan Silva Picanço, Clezio Marcos Denardini, Paulo Alexandre Bronzato Nogueira, Laysa Cristina Araujo Resende, Carolina Sousa Carmo, Sony Su Chen, Paulo França Barbosa-Neto, and Esmeralda Romero-Hernandez
Ann. Geophys., 40, 503–517, https://doi.org/10.5194/angeo-40-503-2022, https://doi.org/10.5194/angeo-40-503-2022, 2022
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In this work, we use the Disturbance Ionosphere indeX (DIX) to study equatorial plasma bubble (EPB) events over the Brazilian equatorial and low latitudes. Our results showed that the DIX detected EPB disturbances in terms of their intensity and occurrence times. Therefore, these responses agreed with the ionosphere behavior before, during, and after the studied EPBs. Finally, these disturbances tended to be higher (lower) in high (low) solar activity.
Laysa C. A. Resende, Yajun Zhu, Clezio M. Denardini, Sony S. Chen, Ronan A. J. Chagas, Lígia A. Da Silva, Carolina S. Carmo, Juliano Moro, Diego Barros, Paulo A. B. Nogueira, José P. Marchezi, Giorgio A. S. Picanço, Paulo Jauer, Régia P. Silva, Douglas Silva, José A. Carrasco, Chi Wang, and Zhengkuan Liu
Ann. Geophys., 40, 191–203, https://doi.org/10.5194/angeo-40-191-2022, https://doi.org/10.5194/angeo-40-191-2022, 2022
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This study showed the ionospheric response over low-latitude regions in Brazil predicted by Martínez-Ledesma et al. (2020) for the solar eclipse event on 14 December 2020. We used a multi-instrumental and modeling analysis to observe the modifications in the E and F regions and the Es layers over Campo Grande and Cachoeira Paulista. The results showed that solar eclipses can cause significant ionosphere modifications even though they only partially reach the Brazilian low-latitude regions.
Joyrles Fernandes de Moraes, Igo Paulino, Lívia R. Alves, and Clezio Marcos Denardini
Ann. Geophys., 38, 881–888, https://doi.org/10.5194/angeo-38-881-2020, https://doi.org/10.5194/angeo-38-881-2020, 2020
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Effects of space weather events in technological systems were studied in the tropical region of Brazil by investigating the Bolivia–Brazil pipeline during space weather events with different intensities. The results presented significant corrosion levels during the 17 March 2015 geomagnetic storm and showed that the effects of space weather must be accounted for, even in low latitudes, since the lifetime of the pipelines can be reduced.
Oluwakemi Dare-Idowu, Igo Paulino, Cosme A. O. B. Figueiredo, Amauri F. Medeiros, Ricardo A. Buriti, Ana Roberta Paulino, and Cristiano M. Wrasse
Ann. Geophys., 38, 507–516, https://doi.org/10.5194/angeo-38-507-2020, https://doi.org/10.5194/angeo-38-507-2020, 2020
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Some strong gravity wave activity occurred and was observed on 8 April 2005. This work reports the spectral characteristics of these waves using OH airglow images captured by the all-sky imager installed at São João do Cariri (7.4° S, 36.5° W). A preferential propagation direction was observed due to the positioning of the source and also due to the wind filtering effect. Furthermore, the source of these waves was identified by performing reverse-ray tracing analysis.
Juliano Moro, Jiyao Xu, Clezio Marcos Denardini, Laysa Cristina Araújo Resende, Régia Pereira Silva, Sony Su Chen, Giorgio Arlan da Silva Picanço, Liu Zhengkuan, Hui Li, Chunxiao Yan, Chi Wang, and Nelson Jorge Schuch
Ann. Geophys., 38, 457–466, https://doi.org/10.5194/angeo-38-457-2020, https://doi.org/10.5194/angeo-38-457-2020, 2020
Short summary
Short summary
The monthly averages of the F2 critical frequency (foF2), its peak height (hmF2), and the E-region critical frequency (foE) acquired by the DPS4-D installed in Santa Maria, Brazil, is compared to the International Reference Ionosphere (IRI-2016) model predictions. It is important to test the performance of the IRI over Santa Maria because it is located in the SAMA, which is a region particularly important for high-frequency (HF) ground-to-satellite navigation signals.
Regia Pereira da Silva, Clezio Marcos Denardini, Manilo Soares Marques, Laysa Cristina Araujo Resende, Juliano Moro, Giorgio Arlan da Silva Picanço, Gilvan Luiz Borba, and Marcos Aurelio Ferreira dos Santos
Ann. Geophys., 38, 27–34, https://doi.org/10.5194/angeo-38-27-2020, https://doi.org/10.5194/angeo-38-27-2020, 2020
Short summary
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In this work, we studied the HILDCAA disturbance time effects in the TEC by analyzing local time and seasonal dependences, and the influences of the solar wind velocity on a sample of 10 intervals occurring in 2015 and 2016. The main results show great variability in the hourly distribution of the dTEC between one interval and another, seasonal behavior different from that presented by geomagnetic storms, and interestingly no relation between the dTEC disturbances and the magnitude of the HSS.
Maurício J. A. Bolzan, Clezio M. Denardini, and Alexandre Tardelli
Ann. Geophys., 36, 937–943, https://doi.org/10.5194/angeo-36-937-2018, https://doi.org/10.5194/angeo-36-937-2018, 2018
Laysa C. A. Resende, Christina Arras, Inez S. Batista, Clezio M. Denardini, Thainá O. Bertollotto, and Juliano Moro
Ann. Geophys., 36, 587–593, https://doi.org/10.5194/angeo-36-587-2018, https://doi.org/10.5194/angeo-36-587-2018, 2018
Short summary
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We present new results on the behavior of sporadic E layers (Es layers) using GPS (global positioning system) radio occultation (RO) measurements obtained from the FORMOSAT-3/COSMIC satellites and digisonde data over Cachoeira Paulista, a low-latitude station in Brazil.
Paulo A. B. Nogueira, Mangalathayil A. Abdu, Jonas R. Souza, Clezio M. Denardini, Paulo F. Barbosa Neto, João P. Serra de Souza da Costa, and Ana P. M. Silva
Ann. Geophys., 36, 139–147, https://doi.org/10.5194/angeo-36-139-2018, https://doi.org/10.5194/angeo-36-139-2018, 2018
Short summary
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We have analyzed the low-latitude ionospheric responses to solar flares. In particular we show for the first time that 5 to 8 min of time delay is present in the peak effect in the EEJ, with respect that of Sq current outside the magnetic equator, in response to the flare radiation enhancement. We propose that the flare induced enhancement in neutral wind occurring with a time delay could be responsible for a delayed zonal electric field disturbance driving the EEJ.
Diego Barros, Hisao Takahashi, Cristiano M. Wrasse, and Cosme Alexandre O. B. Figueiredo
Ann. Geophys., 36, 91–100, https://doi.org/10.5194/angeo-36-91-2018, https://doi.org/10.5194/angeo-36-91-2018, 2018
Cosme Alexandre O. B. Figueiredo, Ricardo A. Buriti, Igo Paulino, John W. Meriwether, Jonathan J. Makela, Inez S. Batista, Diego Barros, and Amauri F. Medeiros
Ann. Geophys., 35, 953–963, https://doi.org/10.5194/angeo-35-953-2017, https://doi.org/10.5194/angeo-35-953-2017, 2017
Related subject area
Subject: Earth's ionosphere & aeronomy | Keywords: Ionospheric irregularities
F-region drift current and magnetic perturbation distribution by the X-wave heating ionosphere
Fluid models capturing Farley–Buneman instabilities
Temporal and altitudinal variability of the spread F observed by the VHF radar over Christmas Island
Effect of neutral winds on the creation of non-specular meteor trail echoes
Simultaneous ground-based and in situ Swarm observations of equatorial F-region irregularities over Jicamarca
Occurrence climatology of equatorial plasma bubbles derived using FormoSat-3 ∕ COSMIC GPS radio occultation data
Localized total electron content enhancements in the Southern Hemisphere
Stratification observed by the in situ plasma density measurements from the Swarm satellites
Structural characterization of the equatorial F region plasma irregularities in the multifractal context
Traits of sub-kilometre F-region irregularities as seen with the Swarm satellites
Equatorial plasma bubbles developing around sunrise observed by an all-sky imager and global navigation satellite system network during storm time
Investigation of the relationship between the spatial gradient of total electron content (TEC) between two nearby stations and the occurrence of ionospheric irregularities
Research on small-scale structures of ice particle density and electron density in the mesopause region
Observation of seasonal asymmetry in the range spread F occurrence at different longitudes during low and moderate solar activity
Identifying a possible stratification phenomenon in ionospheric F2 layer using the data observed by the DEMETER satellite: method and results
Global sounding of F region irregularities by COSMIC during a geomagnetic storm
On the convection of ionospheric density features
The ionospheric response over the UK to major bombing raids during World War II
Yong Li, Hui Li, Jian Wu, Xingbao Lv, Chengxun Yuan, Ce Li, and Zhongxiang Zhou
Ann. Geophys., 41, 541–549, https://doi.org/10.5194/angeo-41-541-2023, https://doi.org/10.5194/angeo-41-541-2023, 2023
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According to plasma drift theory, charged particles will drift when they are subjected to external forces, thus generating a drift current. In this paper, we establish the drift current and magnetic perturbation model in the ionosphere. Based on the HAARP ionospheric background, we analyze the properties of drift current and magnetic perturbation. This work provides guidance for a better understanding of ionospheric current distributions and magnetic perturbations.
Enrique L. Rojas, Keaton J. Burns, and David L. Hysell
Ann. Geophys., 41, 281–287, https://doi.org/10.5194/angeo-41-281-2023, https://doi.org/10.5194/angeo-41-281-2023, 2023
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The standard linear fluid theory of Farley and Buneman predicts that kinetic physics are required to avoid the artificial growth of smaller structures. We explore the possibility of simulating the Farley–Buneman instability using, for the first time, a fully fluid five-moment model. This is the first time a fully fluid model has been used to simulate the Farley–Buneman instability. The results obtained with both models are qualitatively consistent with the ones from kinetic simulations.
Ricardo Yvan de La Cruz Cueva, Eurico Rodrigues de Paula, and Acácio Cunha Neto
Ann. Geophys., 40, 563–570, https://doi.org/10.5194/angeo-40-563-2022, https://doi.org/10.5194/angeo-40-563-2022, 2022
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This paper brings analysis of spread-F echoes along the years of 2003 to 2012 from Christmas Island radar. We organize our data with the objective of observing the peak time and altitude distribution. Our results indicate the peak time occurrence of echoes to be distributed closer to local sunset during solar maximum and around midnight during solar minimum; meanwhile, the peak altitude echoes show higher altitude occurrences during solar maxima and lower altitudes during solar minima.
Freddy Galindo, Julio Urbina, and Lars Dyrud
Ann. Geophys., 39, 709–719, https://doi.org/10.5194/angeo-39-709-2021, https://doi.org/10.5194/angeo-39-709-2021, 2021
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Micro-size particles entering the Earth’s atmosphere do not emit enough light to be observed as meteors, but they can be probed with radars. The echo from these meteors depends on particle size and the atmosphere in which the particle travels. In this paper, we study the importance of neutral winds in forming meteor returns sensed by radars. We show that meteor trails can exhibit unique radar signatures due to neutral winds, explaining unique signatures in radar maps.
Sharon Aol, Stephan Buchert, Edward Jurua, and Marco Milla
Ann. Geophys., 38, 1063–1080, https://doi.org/10.5194/angeo-38-1063-2020, https://doi.org/10.5194/angeo-38-1063-2020, 2020
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Ionospheric irregularities are a common phenomenon in the low-latitude ionosphere. In this paper, we compared simultaneous observations of plasma plumes by the JULIA radar, ionogram spread F generated from ionosonde observations installed at the Jicamarca Radio Observatory, and irregularities observed in situ by Swarm to determine whether Swarm in situ observations can be used as indicators of the presence of plasma plumes and spread F on the ground.
Ankur Kepkar, Christina Arras, Jens Wickert, Harald Schuh, Mahdi Alizadeh, and Lung-Chih Tsai
Ann. Geophys., 38, 611–623, https://doi.org/10.5194/angeo-38-611-2020, https://doi.org/10.5194/angeo-38-611-2020, 2020
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The paper focuses on the analyses of the global occurrence of equatorial plasma bubble events using S4 data that were calculated from GPS radio occultation measurements of the FormoSat-3/COSMIC mission. The advantage in using radio occultation data is that we get information not only on the occurrence and intensity of the equatorial bubble events, but also on the altitude distribution. We analyzed a 10.5-year time series of COSMIC data and demonstrated a strong dependence on the solar cycle.
Ilya K. Edemskiy
Ann. Geophys., 38, 591–601, https://doi.org/10.5194/angeo-38-591-2020, https://doi.org/10.5194/angeo-38-591-2020, 2020
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This paper investigates a feature in the Southern Hemisphere ionosphere that is observed near midday in the form of a localized enhancement of the electron density. After being discovered in global ionospheric maps, the enhancements were also observed via in situ measurements of the electron concentration. The probability of detecting an enhancement is maximal during the autumn–winter period and does not seem to be directly dependent on geomagnetic indices or solar wind parameters.
Xiuying Wang, Wanli Cheng, Zihan Zhou, Dehe Yang, Jing Cui, and Feng Guo
Ann. Geophys., 38, 517–526, https://doi.org/10.5194/angeo-38-517-2020, https://doi.org/10.5194/angeo-38-517-2020, 2020
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To get the global distribution of the stratification phenomenon, the in situ plasma density measurements, obtained by the Swarm satellites orbiting at different altitudes above the F2 peak, are used to study this phenomenon. The continuous morphology of this phenomenon and its features along the latitudinal direction are obtained, and a new discovery from the in situ measurements is the stratification on southern mid-latitudes.
Neelakshi Joshi, Reinaldo R. Rosa, Siomel Savio, Esfhan Alam Kherani, Francisco Carlos de Meneses, Stephan Stephany, and Polinaya Muralikrishna
Ann. Geophys., 38, 445–456, https://doi.org/10.5194/angeo-38-445-2020, https://doi.org/10.5194/angeo-38-445-2020, 2020
Sharon Aol, Stephan Buchert, and Edward Jurua
Ann. Geophys., 38, 243–261, https://doi.org/10.5194/angeo-38-243-2020, https://doi.org/10.5194/angeo-38-243-2020, 2020
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During the night, in the F region, equatorial ionospheric irregularities manifest as plasma depletions observed by satellites and may cause radio signals to fluctuate. We checked the distribution traits of ionospheric F-region irregularities in the low latitudes using 16 Hz electron density observations made by the faceplate onboard Swarm satellites. Using the high-resolution faceplate data, we were able to identify ionospheric irregularities of scales of only a few hundred metres.
Kun Wu, Jiyao Xu, Xinan Yue, Chao Xiong, Wenbin Wang, Wei Yuan, Chi Wang, Yajun Zhu, and Ji Luo
Ann. Geophys., 38, 163–177, https://doi.org/10.5194/angeo-38-163-2020, https://doi.org/10.5194/angeo-38-163-2020, 2020
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An equatorial plasma bubble (EPB) event, emerging near dawn and developing after sunrise, was simultaneously observed by an all-sky imager and the global navigation satellite system (GNSS) network. The observed EPBs showed westward drifts, different from post-sunset EPBs. The EPBs occurred in the recovery phase of a geomagnetic storm, possibly playing a key role in initializing their developments. The results provide a new perspective of EPBs, enriching our knowledge of ionospheric irregularity.
Teshome Dugassa, John Bosco Habarulema, and Melessew Nigussie
Ann. Geophys., 37, 1161–1180, https://doi.org/10.5194/angeo-37-1161-2019, https://doi.org/10.5194/angeo-37-1161-2019, 2019
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The relation between the occurrence of ionospheric irregularities and the spatial gradient of TEC derived from two closely located stations, located within the equatorial region over Ethiopia, was investigated. The relationship between σ(∆TEC/∆long) and ROTIave correlate linearly with correlation coefficients of C = 0.7975 and C = 0.7915 over ASAB and DEBK, respectively. In addition to latitudinal gradients, the longitudinal gradient of TEC has a significant contribution to the TEC fluctuations.
Ruihuan Tian, Jian Wu, Jinxiu Ma, Yonggan Liang, Hui Li, Chengxun Yuan, Yongyuan Jiang, and Zhongxiang Zhou
Ann. Geophys., 37, 1079–1094, https://doi.org/10.5194/angeo-37-1079-2019, https://doi.org/10.5194/angeo-37-1079-2019, 2019
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The density distribution of ice particles and electrons near the boundary of the polar mesosphere summer echo (PMSE) region is studied. The results show that when the radius distribution function of the condensation nucleus is a Gaussian type, for a certain range of the condensation core radius, sharp peaks with a meter scale appear in the density profiles of ice particles and electrons. These small-scale structures of electron density may be one of the causes of the PMSE phenomenon.
Abimbola O. Afolayan, Mandeep Jit Singh, Mardina Abdullah, Suhaila M. Buhari, Tatsuhiro Yokoyama, and Pornchai Supnithi
Ann. Geophys., 37, 733–745, https://doi.org/10.5194/angeo-37-733-2019, https://doi.org/10.5194/angeo-37-733-2019, 2019
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The equatorial spread F (ESF) is a nighttime phenomenon that can have a deleterious effect on the radio communication system. We investigated the parameters influencing the seasonal morphology of the range type spread F (RSF) using ionosonde data from different longitude sectors. The observed RSF occurrence features showed distinct patterns across these sectors, including seasonal asymmetry. This asymmetry was attributed to the probable effect of the zonal wind reversal and gravity waves.
Xiuying Wang, Dehe Yang, Dapeng Liu, and Wei Chu
Ann. Geophys., 37, 645–655, https://doi.org/10.5194/angeo-37-645-2019, https://doi.org/10.5194/angeo-37-645-2019, 2019
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To check the difference between data observed at different altitudes of the DEMETER satellite, a statistical method is adopted to evaluate whether data difference is caused by normal data fluctuation or by altitude adjustment. Based on the method, in situ electron density data at higher altitudes are found to be greater than those at lower altitudes. We speculate that this phenomenon is caused by stratification above F2 peak region. The proposed method is useful when comparing fluctuated data.
Klemens Hocke, Huixin Liu, Nicholas Pedatella, and Guanyi Ma
Ann. Geophys., 37, 235–242, https://doi.org/10.5194/angeo-37-235-2019, https://doi.org/10.5194/angeo-37-235-2019, 2019
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The GPS radio occultation data of the COSMIC-FORMOSAT-3 mission are used to visualize the global distribution of ionospheric irregularities in the F2 region during a geomagnetic storm, at solar minimum, and at solar maximum.
John D. de Boer, Jean-Marc A. Noël, and Jean-Pierre St.-Maurice
Ann. Geophys., 37, 201–214, https://doi.org/10.5194/angeo-37-201-2019, https://doi.org/10.5194/angeo-37-201-2019, 2019
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Modelling aurorae, we asked what boundary condition (BC) to use for the E field on the upper boundary. Typically a Dirichlet BC is used, since processes above the domain generate E. But then conductivity structures trigger FACs driven immediately by magnetospheric convection, even though it is a finite energy source, delayed by the Alfvén speed. If the BC is not ideal, then E x B drift in the ionosphere depends on the plasma's properties. So we investigated.
Christopher J. Scott and Patrick Major
Ann. Geophys., 36, 1243–1254, https://doi.org/10.5194/angeo-36-1243-2018, https://doi.org/10.5194/angeo-36-1243-2018, 2018
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Short summary
The variability of the Earth's ionosphere (the electrified region of the Earth's upper atmosphere) results from external forcing from above (through solar activity and space weather effects) and from below (via natural sources such as lightning storms and tectonics). Bombing raids over Europe during World War II were used to determine the quantitative impact of explosions on the ionosphere. It was found that raids using more than 300 tonnes of explosives weakened the ionosphere for up to 5 h.
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Short summary
The Brazilian Space Weather Study and Monitoring Program (Embrace) has been developing different indexes that describe ionospheric effects in the Brazilian sector. The main purpose of this work was to produce a new ionospheric scale based on the analysis of the ionospheric plasma drift velocity. We analyzed 7 years of data in order to construct a standardized scale. The results of this new index allow us to evaluate the impacts of ionospheric phenomena in the space weather environment.
The Brazilian Space Weather Study and Monitoring Program (Embrace) has been developing different...
Special issue