Quantifying the EEJ current with ground-based ionosonde inferred vertical E × B drifts in the morning hours over Ilorin, West Africa
- 59 Downloads
The relationship between the ground-based inferred vertical E × B drifts, Vz, and the magnetic equatorial electrojet current during the year of solar minima was presented. Both the diurnal and seasonal Vz variations are positively directed during the daytime and negative at nighttime. The evening time pre-reversal enhancement occurs around 19:00 LT. The fairly strong linear relationship between the electrojet current strength and Vz exhibited higher correlations during the daytime (06:00–16:00 LT). The maximum morning time proxy parameter described by E = [d (ΔH ILR)/dt]max in the morning hours, indicating the east-west electric field in the EEJ, corresponds reasonably well with the E × B drift and, hence, can be used as a proxy parameter for representing Vz in the morning hours. The daytime EEJ magnitude seasonal changes are connected with a change in conductivity emerging from the action of turbulence and divergence of momentum flux. These waves above the dynamo region are suggested to lead to partial counter electrojet during the equinoctial months.
Keywordsequatorial electrojet E × B drifts counter electrojet electric field pre-reversal enhancement
Unable to display preview. Download preview PDF.
- Abdu, M.A., G.O. Walker, B.M. Reddy, E.R. de Paula, J.H.A. Sobral, and B.G. Fejer (1993), Global scale equatorial ionization anomaly (EIA) response to magnetospheric disturbances based on the May-June 1987 SUNDIALcoordinated observations, Ann. Geophys. 11,7, 585–594.Google Scholar
- Abdu, M.A., T.K. Ramkumar, I.S. Batista, C.G.M. Brum, H. Takahasi, B.W. Reinisch, and J.H.A. Sobral (2006), Planetary wave signatures in the equatorial atmosphere-ionosphere system, and mesosphere — E- and F-region coupling, J. Atmos. Sol.-Terr. Phys. 68,3–5, 509–522, DOI: 10.1016/j.jastp.2005.03.019.CrossRefGoogle Scholar
- Adebesin, B.O., J.O. Adeniyi, I.A. Adimula, and B.W. Reinisch (2013b), Equatorial vertical plasma drift velocities and electron densities inferred from groundbased ionosonde measurements during low solar activity, J. Atmos. Sol.-Terr. Phys. 97, 58–64, DOI: 10.1016/j.jastp.2013.02.010.CrossRefGoogle Scholar
- Adimula, I.A., A.B. Rabiu, Y. Yumoto, and the MAGDAS Group (2011), Geomagnetic field variations from some equatorial electrojet stations, Sun Geosphere 6,2, 45–49.Google Scholar
- Araujo-Pradere, E.A., D.N. Anderson, M. Fedrizzi, and R. Stoneback (2010), Quantifying the daytime, equatorial E × B drift velocities at the boundaries of the 4-cell tidal structure using C/NOFS’ CINDI observations. In: P. Doherty, M. Hernández-Pajares, J.M. Juan, J. Sanz, and A. Aragon-Angel (eds.), Proc. Int. Beacon Satellite Symposium 2010, 7–11 June 2010, Barcelona, Spain.Google Scholar
- Huang, X., and B.W. Reinisch (1996), Vertical electron density profiles from Digisonde ionograms. The average representative profile, Ann. Geophys. 39,4, 751–756, DOI: 10.4401/ag-4010.Google Scholar
- Rabiu, A.B., A.I. Mamukuyomi, and E.O. Joshua (2007), Variability of equatorial ionosphere inferred from geomagnetic field measurements, Bull. Astron. Soc. India 35,4, 607–618.Google Scholar
- Vineeth, C., T.K. Pant, and M.M. Hossain (2012a), Enhanced gravity wave activity over the equatorial MLT region during counter electrojet events, Indian J. Radio Space Phys. 41,2, 258–263.Google Scholar
- Yumoto, K., and the MAGDAS Group (2007), Space weather activities at SERC for IHY: MAGDAS, Bull. Astron. Soc. India 35,4, 511–522.Google Scholar