Articles | Volume 35, issue 1
Ann. Geophys., 35, 123–132, 2017

Special issue: The 14th International Symposium on Equatorial Aeronomy

Ann. Geophys., 35, 123–132, 2017

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 Bolaji1,2, Oluwafisayo Owolabi1, Elijah Falayi7, Emmanuel Jimoh1, Afolabi Kotoye8, Olumide Odeyemi1, Babatunde Rabiu3, Patricia Doherty4, Endawoke Yizengaw4, Yosuke Yamazaki5, Jacob Adeniyi6, Rafiat Kaka10, and Kehinde Onanuga9 Olawale Bolaji et al.
  • 1Department of Physics, University of Lagos, Akoka – Yaba, Lagos, Nigeria
  • 2Department of Physics, University of Tasmania, Hobart, Australia
  • 3Center for Atmospheric Research (CAR), National Space Research and Development Agency (NASRDA), Kogi State University Campus, Anyigba, 270109, Nigeria
  • 4Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts, USA
  • 5Department of Physics, Lancaster University, Lancaster, UK
  • 6Department of Physics, University of Ilorin, Kwara, Nigeria
  • 7Department of Physics, Tai Solarin University of Education, Ijagun, Ijebu-Ode, Nigeria
  • 8Abraham Adesanya Polytechnic, Ijebu-Igbo, Nigeria
  • 9Department of Science Laboratory Technology, Lagos State Polytechnics, Lagos, Nigeria
  • 10Department of Physics, Afe Babalola University, Ado-Ekiti, Nigeria

Abstract. In this work, we investigated the veracity of an ion continuity equation in controlling equatorial ionization anomaly (EIA) morphology using total electron content (TEC) of 22 GPS receivers and three ground-based magnetometers (Magnetic Data Acquisition System, MAGDAS) over Africa and the Middle East (Africa–Middle East) during the quietest periods. Apart from further confirmation of the roles of equatorial electrojet (EEJ) and integrated equatorial electrojet (IEEJ) in determining hemispheric extent of EIA crest over higher latitudes, we found some additional roles played by thermospheric meridional neutral wind. Interestingly, the simultaneous observations of EIA crests in both hemispheres of Africa–Middle East showed different morphology compared to that reported over Asia. We also observed interesting latitudinal twin EIA crests domiciled at the low latitudes of the Northern Hemisphere. Our results further showed that weak EEJ strength associated with counter electrojet (CEJ) during sunrise hours could also trigger twin EIA crests over higher latitudes.

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.