Articles | Volume 35, issue 1
https://doi.org/10.5194/angeo-35-123-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Special issue:
https://doi.org/10.5194/angeo-35-123-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Regular paper
| 
20 Jan 2017
Regular paper |
| 20 Jan 2017
Observations of equatorial ionization anomaly over Africa and Middle East during a year of deep minimum
Olawale Bolaji
CORRESPONDING AUTHOR
Department of Physics, University of Lagos, Akoka – Yaba, Lagos,
Nigeria
Department of Physics, University of Tasmania, Hobart, Australia
Oluwafisayo Owolabi
Department of Physics, University of Lagos, Akoka – Yaba, Lagos,
Nigeria
Elijah Falayi
Department of Physics, Tai Solarin University of Education, Ijagun,
Ijebu-Ode, Nigeria
Emmanuel Jimoh
Department of Physics, University of Lagos, Akoka – Yaba, Lagos,
Nigeria
Afolabi Kotoye
Abraham Adesanya Polytechnic, Ijebu-Igbo, Nigeria
Olumide Odeyemi
Department of Physics, University of Lagos, Akoka – Yaba, Lagos,
Nigeria
Babatunde Rabiu
Center for Atmospheric Research (CAR), National Space Research and
Development Agency (NASRDA), Kogi State University Campus, Anyigba, 270109,
Nigeria
Patricia Doherty
Institute for Scientific Research, Boston College, Chestnut Hill,
Massachusetts, USA
Endawoke Yizengaw
Institute for Scientific Research, Boston College, Chestnut Hill,
Massachusetts, USA
Yosuke Yamazaki
Department of Physics, Lancaster University, Lancaster, UK
Jacob Adeniyi
Department of Physics, University of Ilorin, Kwara, Nigeria
Rafiat Kaka
Department of Physics, Afe Babalola University, Ado-Ekiti, Nigeria
Kehinde Onanuga
Department of Science Laboratory Technology, Lagos State Polytechnics,
Lagos, Nigeria
Related authors
Irewola Aaron Oludehinwa, Andrei Velichko, Olasunkanmi Isaac Olusola, Olawale Segun Bolaji, Norbert Marwan, Babaola O. Ogunsua, Abdullahi Ndzi Njah, and Timothy O. Ologun
EGUsphere, https://doi.org/10.5194/egusphere-2024-3554, https://doi.org/10.5194/egusphere-2024-3554, 2024
Short summary
Short summary
The contributing influence of SSW to regional ionosphere through chaos theory is examined. We found that ionospheric chaos is more pronounced in the European sector compared to Africa sector during SSW. Evidence of orderliness behavior in regional ionosphere of African sector was observed. Finally, we noticed that after the peak phase of SSW, ionospheric chaos is found to be more pronounced.
Irewola Aaron Oludehinwa, Olasunkanmi Isaac Olusola, Olawale Segun Bolaji, Olumide Olayinka Odeyemi, and Abdullahi Ndzi Njah
Nonlin. Processes Geophys., 28, 257–270, https://doi.org/10.5194/npg-28-257-2021, https://doi.org/10.5194/npg-28-257-2021, 2021
Short summary
Short summary
The MLE and ApEn values of the Dst indicate that chaotic and dynamical complexity responses are high during minor geomagnetic storms, reduce at moderate geomagnetic storms and decline further during major geomagnetic storms.
However, the MLE and ApEn values obtained from solar wind electric field (VBs) indicate that chaotic and dynamical complexity responses are high with no significant difference between the periods that are associated with minor, moderate and major geomagnetic storms.
Bolarinwa J. Adekoya, Babatunde O. Adebesin, Timothy W. David, Stephen O. Ikubanni, Shola J. Adebiyi, Olawale S. Bolaji, and Victor U. Chukwuma
Ann. Geophys., 37, 171–182, https://doi.org/10.5194/angeo-37-171-2019, https://doi.org/10.5194/angeo-37-171-2019, 2019
Short summary
Short summary
We present the dynamics of perturbations during a solar eclipse using rare parameters for eclipse study. Reduction in solar radiation and natural gas heating are the cause of the observed changes. The use of the bottomside F-layer parameters to probe the topside ionosphere established their interrelationship. The implication is that eclipse-caused perturbation could be better explained using some ionosonde parameters.
Victor Adetayo Eyelade, Adekola Olajide Adewale, Andrew Ovie Akala, Olawale Segun Bolaji, and A. Babatunde Rabiu
Ann. Geophys., 35, 701–710, https://doi.org/10.5194/angeo-35-701-2017, https://doi.org/10.5194/angeo-35-701-2017, 2017
Short summary
Short summary
The study examined the diurnal and seasonal variations in total electron content (TEC) over Nigeria. The derived GPS TEC across all the stations demonstrated consistent minimum diurnal variations during the pre-sunrise hours, increased with a sharp gradient during the sunrise period, attained a postnoon maximum at about 14:00 LT, and then fell to a minimum just before sunset. The seasonal variation depicted a semi-annual distribution with higher values around equinoxes than solstices.
Irewola Aaron Oludehinwa, Andrei Velichko, Olasunkanmi Isaac Olusola, Olawale Segun Bolaji, Norbert Marwan, Babaola O. Ogunsua, Abdullahi Ndzi Njah, and Timothy O. Ologun
EGUsphere, https://doi.org/10.5194/egusphere-2024-3554, https://doi.org/10.5194/egusphere-2024-3554, 2024
Short summary
Short summary
The contributing influence of SSW to regional ionosphere through chaos theory is examined. We found that ionospheric chaos is more pronounced in the European sector compared to Africa sector during SSW. Evidence of orderliness behavior in regional ionosphere of African sector was observed. Finally, we noticed that after the peak phase of SSW, ionospheric chaos is found to be more pronounced.
Markus Kunze, Christoph Zülicke, Tarique Adnan Siddiqui, Claudia Christine Stephan, Yosuke Yamazaki, Claudia Stolle, Sebastian Borchert, and Hauke Schmidt
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2024-191, https://doi.org/10.5194/gmd-2024-191, 2024
Preprint under review for GMD
Short summary
Short summary
We present the Icosahedral Nonhydrostatic (ICON) general circulation model with upper atmosphere extension with the physics package for numerical weather prediction (UA-ICON(NWP)). The parameters for the gravity wave parameterizations were optimized, and realistic modelling of the thermal and dynamic state of the mesopause regions was achieved. UA-ICON(NWP) now shows a realistic frequency of major sudden stratospheric warmings and well-represented solar tides in temperature.
Yosuke Yamazaki
Geosci. Model Dev., 16, 4749–4766, https://doi.org/10.5194/gmd-16-4749-2023, https://doi.org/10.5194/gmd-16-4749-2023, 2023
Short summary
Short summary
The Earth's atmosphere can support various types of global-scale waves. Some waves propagate eastward and others westward, and they can have different zonal wavenumbers. The Fourier–wavelet analysis is a useful technique for identifying different components of global-scale waves and their temporal variability. This paper introduces an easy-to-implement method to derive Fourier–wavelet spectra from 2-D space–time data. Application examples are presented using atmospheric models.
Olalekan David Ayokunnu, Oluseyi Enitan Ogunsola, Jacob Olusegun Adeniyi, and Ismail Adekunle Animasaun
EGUsphere, https://doi.org/10.5194/egusphere-2023-107, https://doi.org/10.5194/egusphere-2023-107, 2023
Preprint archived
Short summary
Short summary
The in-depth study of the ionospheric electron density profile contributes significantly to our understanding of the ionosphere, its dynamic nature and characteristics of radio wave for telecommunication. it was observed that the results from Ilorin and Fortaleza are similar and that of Jicamarca are different from those of other two stations. This is the second time in our studies that two stations from different latitude will be presented as being having similar profile.
Juliana Jaen, Toralf Renkwitz, Jorge L. Chau, Maosheng He, Peter Hoffmann, Yosuke Yamazaki, Christoph Jacobi, Masaki Tsutsumi, Vivien Matthias, and Chris Hall
Ann. Geophys., 40, 23–35, https://doi.org/10.5194/angeo-40-23-2022, https://doi.org/10.5194/angeo-40-23-2022, 2022
Short summary
Short summary
To study long-term trends in the mesosphere and lower thermosphere (70–100 km), we established two summer length definitions and analyzed the variability over the years (2004–2020). After the analysis, we found significant trends in the summer beginning of one definition. Furthermore, we were able to extend one of the time series up to 31 years and obtained evidence of non-uniform trends and periodicities similar to those known for the quasi-biennial oscillation and El Niño–Southern Oscillation.
Irewola Aaron Oludehinwa, Olasunkanmi Isaac Olusola, Olawale Segun Bolaji, Olumide Olayinka Odeyemi, and Abdullahi Ndzi Njah
Nonlin. Processes Geophys., 28, 257–270, https://doi.org/10.5194/npg-28-257-2021, https://doi.org/10.5194/npg-28-257-2021, 2021
Short summary
Short summary
The MLE and ApEn values of the Dst indicate that chaotic and dynamical complexity responses are high during minor geomagnetic storms, reduce at moderate geomagnetic storms and decline further during major geomagnetic storms.
However, the MLE and ApEn values obtained from solar wind electric field (VBs) indicate that chaotic and dynamical complexity responses are high with no significant difference between the periods that are associated with minor, moderate and major geomagnetic storms.
Bolarinwa J. Adekoya, Babatunde O. Adebesin, Timothy W. David, Stephen O. Ikubanni, Shola J. Adebiyi, Olawale S. Bolaji, and Victor U. Chukwuma
Ann. Geophys., 37, 171–182, https://doi.org/10.5194/angeo-37-171-2019, https://doi.org/10.5194/angeo-37-171-2019, 2019
Short summary
Short summary
We present the dynamics of perturbations during a solar eclipse using rare parameters for eclipse study. Reduction in solar radiation and natural gas heating are the cause of the observed changes. The use of the bottomside F-layer parameters to probe the topside ionosphere established their interrelationship. The implication is that eclipse-caused perturbation could be better explained using some ionosonde parameters.
Tarique A. Siddiqui, Astrid Maute, Nick Pedatella, Yosuke Yamazaki, Hermann Lühr, and Claudia Stolle
Ann. Geophys., 36, 1545–1562, https://doi.org/10.5194/angeo-36-1545-2018, https://doi.org/10.5194/angeo-36-1545-2018, 2018
Short summary
Short summary
Extreme meteorological events such as SSWs induce variabilities in the ionosphere by modulating the atmospheric tides, and these variabilities can be comparable to a moderate geomagnetic storm. The equatorial electrojet (EEJ) is a narrow ribbon of current flowing over the dip equator in the ionosphere and is particularly sensitive to tidal changes. In this study, we use ground-magnetic measurements to investigate the semidiurnal solar and lunar tidal variabilities of the EEJ during SSWs.
Olumide Olayinka Odeyemi, Jacob Adeniyi, Olushola Oladipo, Olayinka Olawepo, Isaac Adimula, and Elijah Oyeyemi
Ann. Geophys., 36, 1457–1469, https://doi.org/10.5194/angeo-36-1457-2018, https://doi.org/10.5194/angeo-36-1457-2018, 2018
Short summary
Short summary
This paper investigates the combined relationship between the GPS TEC and DPS TEC, and validations of IRI TEC and NeQ TEC models. Our findings reveal the suitability of DPS TEC, IRI TEC, and NeQ TEC in place of GPS TEC. The DPS TEC predicts GPS TEC very well during the daytime when PEC contribution is often negligible; however, the dusk period requires a substantial correction. Thus, the changed TEC obtained could be used to improve models for the equatorial station in Africa.
Victor Adetayo Eyelade, Adekola Olajide Adewale, Andrew Ovie Akala, Olawale Segun Bolaji, and A. Babatunde Rabiu
Ann. Geophys., 35, 701–710, https://doi.org/10.5194/angeo-35-701-2017, https://doi.org/10.5194/angeo-35-701-2017, 2017
Short summary
Short summary
The study examined the diurnal and seasonal variations in total electron content (TEC) over Nigeria. The derived GPS TEC across all the stations demonstrated consistent minimum diurnal variations during the pre-sunrise hours, increased with a sharp gradient during the sunrise period, attained a postnoon maximum at about 14:00 LT, and then fell to a minimum just before sunset. The seasonal variation depicted a semi-annual distribution with higher values around equinoxes than solstices.
Fasil Tesema, Rafael Mesquita, John Meriwether, Baylie Damtie, Melessew Nigussie, Jonathan Makela, Daniel Fisher, Brian Harding, Endawoke Yizengaw, and Samuel Sanders
Ann. Geophys., 35, 333–344, https://doi.org/10.5194/angeo-35-333-2017, https://doi.org/10.5194/angeo-35-333-2017, 2017
Short summary
Short summary
Measurements of equatorial thermospheric winds obtained from an optical instrument called a Fabry–Perot interferometer in Ethiopia show a significance difference as compared with other longitudinal sectors. The zonal wind in this sector is small and shows a gradual decrease through out the night. Application of climatological wind and temperature models shows good agreement with the observations over Ethiopia.
Short summary
Movement of plasma to higher latitudes by EIA is known to relate to eastward electric field/EEJ and thermospheric meridional neutral wind. Experiments from GPS measurements that unveil thermospheric meridional neutral wind effect on plasma transportation in the F region are very few compared with electric field/EEJ. This work includes examples of thermospheric meridional neutral wind effects on GPS TEC measurements and their roles in transportation of plasma compared to electric field/EEJ.
Movement of plasma to higher latitudes by EIA is known to relate to eastward electric field/EEJ...
Special issue