Observations of equatorial ionization anomaly over Africa and Middle East during a year of deep minimum

Article, 0038 OPEN
Olawale Bolaji ; Oluwafisayo Owolabi ; Elijah Falayi ; Emmanuel Jimoh ; Afolabi Kotoye ; Olumide Odeyemi ; Babatunde Rabiu ; Patricia Doherty ; Endawoke Yizengaw ; Yosuke Yamazaki ; Jacob Adeniyi ; Rafiat Kaka ; Kehinde Onanuga (2017)

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.
  • References (35)
    35 references, page 1 of 4

    African Geodetic Reference Frame: available at: http://www. afrefdata.org, last access: 18 February 2015.

    Anderson, D., Anghel, A., Yumoto, K., Ishitsuka, M., and Kudeki, E.: Estimating day time vertical ExB drift velocities in the equatorial F-region using ground-based magnetometer observations, Geophys. Res. Lett., 29, 37-1-37-4, doi:10.1029/2001GL014562, 2002.

    Appleton, E. V.: Two anomalies in the ionosphere, Nature, 157, 691-693, 1946.

    Balan, N. and Iyer, K. N.: Equatorial anomaly in ionospheric electron content and its relation to dynamo currents, J. Geophys. Res., 88, 10259-10262, 1983.

    Barbara, A. K., Devi, M., Bardoli, P., and Rehman, K.: Ionosheric effect observed at Gauhati during the solar eclipse of February 16, 1980, Proc Int. Symp. Beacon Satellite studies on the Earth's Environment, 387 pp., 1980.

    Batista, I. S., Diogo, E. M., Souza, J. R., Abdu, M. A., and Bailey, G. J.: Equatorial ionization anomaly: The role of thermospheric wind and the effect of the geomagnetic field secular variation, Aeronomy of the Earth's Atmosphere and Ionosphere, Springer Dordrecht Heidelberg, London New York, 2011.

    Bolaji, O. S., Adeniyi, J. O., Radicella, S. M., and Doherty P. H.: Variability of total electron content over an equatorial West African station during low solar activity, Radio Sci. 47, RS1001, doi:10.1029/2011RS004812, 2012.

    Bolaji, O. S., Adeniyi, J. O., Radicella, S. M., and Doherty, P. H.: Total electron content over and magnetic field intensity over Ilorin, Nigeria, J. Atmos. Sol.-Terr. Phy., 98, 1-11, 2013.

    Bolaji, O. S., Rabiu, A. B., Bello, O. R., Yoshikawa, A., Yumoto, K., Odeyemi, O. O., and Ogunmodimu O.: Spatial variability of solar quiet fields along 960 magnetic meridian in Africa: Results from MAGDAS, J. Geophys. Res., 120, 3883-3898, doi:10.1002/2014JA020728, 2015.

    Bramley, E. N. and Peart, M.: Diffusion and electromagnetic drift in the equatorial F2-region, J. Atmos. Terr. Phys., 27, 1201, doi:10.1016/0021-9169(65)90081-4, 1965.

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