Comparison between African equatorial station ground-based inferred vertical E×B drift, Jicamarca direct measured drift, and IRI model

Adeniyi, J.O. and Adebesin, B.O. and Adimula, I.A. and Oladipo, O.A. and Olawepo, A.O. and Ikubanni, S.O. and Reinisch, B.W. (2014) Comparison between African equatorial station ground-based inferred vertical E×B drift, Jicamarca direct measured drift, and IRI model. Advances in Space Research, 54 (8). pp. 1629-1641. ISSN 02731177

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The Incoherent Scatter Radar measurement over Jicamarca, together with the IRI model-2007 measurements were compared with ground-based digisonde inferred E x B drift over Ilorin in the African region during year of solar minima (F10.7 = 81). Seasonally, Ilorin pre-reversal enhancement (PRE) had peak drift velocities of 7.2, 3.7 and 7.9 m/s for March equinox, September equinox and December solstice respectively, while Jicamarca drifts indicated 13.0, 10.5 and 5.2 m/s; as well as the IRI model with 14.3, 8.4 and 0.7 m/s in similar order. PRE value was insignificant during June solstice. The PRE magnitude of the IRI-model during the equinoxes is twice the value obtained at Ilorin. The daytime E x B drift peaked over Ilorin 1-2h earlier than both the modelled and Jicamarca observations. This could be due to the difference in sunset time at the conjugate points corresponding to the altitude of the observation. During the evening time PRE, the respective correlation coefficients (R) for Vz-F10.7 relation over Jicamarca, Ilorin and the modelled observations are -0.5559, 0.4796 and -0.4979. Similarly, the Vz-Ap relation exhibit excellent anti-correlation coefficient (R = -0.8637) for the IRI-model, -0.4827 over Jicamarca and 0.3479 for Ilorin. Annual mean drift velocities over Jicamarca, Ilorin and IRI model measurements respectively are 10, 5.6 and 10 m/s for the peak PRE observation; 15, 16 and 21 m/s for the daytime pre-sunrise peak values; and -21, -9 and -16 m/s for the nighttime downward reversals. The root-mean square (RMS) deviation between IRI-model and the Ilorin drift between 2000-0500h is 4.37, 2.03, 3.71 and 2.42 m/s for March equinox, June solstice, September equinox and December solstice respectively. For Jicamarca-Ilorin drift relation, RMS deviation is 5.48, 2.30, 3.47 and 1.27 m/s in the same order respectively. Annual hmF2 inferred drift over Ilorin during daytime is higher by a factor of ≈ 2 and 3 at Jicamarca and IRI model measurements respectively; and by a factor of ≈ 5 for both during the night-time period. The limitations in using hmF2 to infer drifts are discussed.

Item Type: Article
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Depositing User: DR. B. OLUFEMI ADEBESIN
Date Deposited: 12 Jun 2015 20:24
Last Modified: 12 Jun 2015 20:24

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