Highlights Study area was an Africa equatorial station during period of solar minima. Ground-based hmF2 inferred vertical drift was compared with IRI model-2007; and Jicamarca. Observational periods are evening-time PRE, daytime pre-sunrise peak, and nighttime reversal peak. The solar (F10.7) and magnetic (Ap) activities relationship were also investigated.

    Abstract The Incoherent Scatter Radar measurement over Jicamarca, together with the IRI model-2007 measurements were compared with ground-based digisonde inferred E×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 7.9m/s for March equinox, September equinox and December solstice respectively, while Jicamarca drifts indicated 13.0, 10.5 and 5.2m/s; as well as the IRI model with 14.3, 8.4 and 0.7m/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×B drift peaked over Ilorin 1–2h earlier than both the modeled 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 modeled 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 10m/s for the peak PRE observation; 15, 16 and 21m/s for the daytime pre-sunrise peak values; and −21, −9 and −16m/s for the nighttime downward reversals. The root-mean square (RMS) deviation between IRI-model and the Ilorin drift between 2000 and 0500h is 4.37, 2.03, 3.71 and 2.42m/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 1.27m/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.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

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


    Beteiligte:
    Adeniyi, J.O. (Autor:in) / Adebesin, B.O. (Autor:in) / Adimula, I.A. (Autor:in) / Oladipo, O.A. (Autor:in) / Olawepo, A.O. (Autor:in) / Ikubanni, S.O. (Autor:in) / Reinisch, B.W. (Autor:in)

    Erschienen in:

    Advances in Space Research ; 54 , 8 ; 1629-1641


    Erscheinungsdatum :

    2014-06-09


    Format / Umfang :

    13 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch