Articles | Volume 37, issue 1
https://doi.org/10.5194/angeo-37-65-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-37-65-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Modeling of GPS total electron content over the African low-latitude region using empirical orthogonal functions
Geoffrey Andima
CORRESPONDING AUTHOR
Department of Physics, Mbarara University of Science and Technology, Mbarara, Uganda
Emirant B. Amabayo
Department of Physics, Mbarara University of Science and Technology, Mbarara, Uganda
Department of Physics, Busitema University, Tororo, Uganda
Edward Jurua
Department of Physics, Mbarara University of Science and Technology, Mbarara, Uganda
Pierre J. Cilliers
South African National Space Agency (SANSA) Space Science, Hermanus, South Africa
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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.
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.
Sylvain M. Ahoua, John Bosco Habarulema, Olivier K. Obrou, Pierre J. Cilliers, and Zacharie K. Zaka
Ann. Geophys., 36, 1161–1170, https://doi.org/10.5194/angeo-36-1161-2018, https://doi.org/10.5194/angeo-36-1161-2018, 2018
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Many studies carried out for model validation are realised under geomagnetically quiet conditions. For climatological models this is not an issue. But for models like NeQuick, which plays a crucial role in daily human activities, it has to be evaluated under different conditions. Our study, which is probably a preliminary study, shows the advantage of the ingestion of ionospheric data. Thus, through this technique, a model could be assessed regardless of the geomagnetic activity.
Patrick Mungufeni, John Bosco Habarulema, Yenca Migoya-Orué, and Edward Jurua
Ann. Geophys., 36, 841–853, https://doi.org/10.5194/angeo-36-841-2018, https://doi.org/10.5194/angeo-36-841-2018, 2018
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We have established that, over the East African region, the trough of the equatorial ionisation anomaly (EIA) during high solar activity and quiet geomagnetic conditions lies slightly south of the magnetic equator. During the equinox and December solstice seasons, and a local time interval of 13:00–15:00, the probability of observing the EIA on days with daytime equatorial electrojet (EEJ) strength ≥ 40 nT was mostly > 80 %.
P. Prikryl, R. Ghoddousi-Fard, L. Spogli, C. N. Mitchell, G. Li, B. Ning, P. J. Cilliers, V. Sreeja, M. Aquino, M. Terkildsen, P. T. Jayachandran, Y. Jiao, Y. T. Morton, J. M. Ruohoniemi, E. G. Thomas, Y. Zhang, A. T. Weatherwax, L. Alfonsi, G. De Franceschi, and V. Romano
Ann. Geophys., 33, 657–670, https://doi.org/10.5194/angeo-33-657-2015, https://doi.org/10.5194/angeo-33-657-2015, 2015
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A series of interplanetary coronal mass ejections in the period 7–17 March 2012 caused geomagnetic storms that strongly affected the high-latitude ionosphere in the Northern and Southern Hemisphere. Interhemispheric comparison of GPS phase scintillation reveals commonalities as well as asymmetries, as a consequence of the coupling between the solar wind and magnetosphere. The interhemispheric asymmetries are primarily caused by the dawn-dusk component of the interplanetary magnetic field.
J. S. de Villiers and P. J. Cilliers
Ann. Geophys., 32, 1263–1275, https://doi.org/10.5194/angeo-32-1263-2014, https://doi.org/10.5194/angeo-32-1263-2014, 2014
Related subject area
Subject: Earth's ionosphere & aeronomy | Keywords: Long-term changes and trends
Long-term trends in the ionospheric response to solar extreme-ultraviolet variations
Rajesh Vaishnav, Christoph Jacobi, and Jens Berdermann
Ann. Geophys., 37, 1141–1159, https://doi.org/10.5194/angeo-37-1141-2019, https://doi.org/10.5194/angeo-37-1141-2019, 2019
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We investigate the ionospheric response to the temporal and spatial dynamics of the solar activity using total electron content (TEC) maps and multiple solar proxies. The maximum correlation at a 16–32-d timescale is observed between the He-II, Mg-II, and F30 with respect to global mean TEC, with an effective time delay of about 1 d. The most suitable proxy to represent the solar activity at the timescales of 16–32 d and 32–64 d is He-II.
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Short summary
Based on hourly averages of the total electron content (TEC), a regional model of the TEC was constructed. Annual averages calculated from monthly medians of the detrended TEC were used to estimate any trends in the TEC over the African low latitudes. A predominantly negative trend in the ionospheric TEC was observed in the vicinity of the dip equator.
Based on hourly averages of the total electron content (TEC), a regional model of the TEC was...