کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1764604 | 1020063 | 2014 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Comparison between African equatorial station ground-based inferred vertical EÂ ÃÂ B drift, Jicamarca direct measured drift, and IRI model
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
علوم فضا و نجوم
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چکیده انگلیسی
The Incoherent Scatter Radar measurement over Jicamarca, together with the IRI model-2007 measurements were compared with ground-based digisonde inferred EÂ ÃÂ B drift over Ilorin in the African region during year of solar minima (F10.7Â =Â 81). Seasonally, Ilorin pre-reversal enhancement (PRE) had peak drift velocities of 7.2, 3.7 and 7.9Â m/s for March equinox, September equinox and December solstice respectively, while Jicamarca drifts indicated 13.0, 10.5 and 5.2Â m/s; as well as the IRI model with 14.3, 8.4 and 0.7Â 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 EÂ ÃÂ B drift peaked over Ilorin 1-2Â h 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 â0.5559, 0.4796 and â0.4979. Similarly, the Vz-Ap relation exhibit excellent anti-correlation coefficient (RÂ =Â â0.8637) for the IRI-model, â0.4827 over Jicamarca and 0.3479 for Ilorin. Annual mean drift velocities over Jicamarca, Ilorin and IRI model measurements respectively are 10, 5.6 and 10Â m/s for the peak PRE observation; 15, 16 and 21Â m/s for the daytime pre-sunrise peak values; and â21, â9 and â16Â m/s for the nighttime downward reversals. The root-mean square (RMS) deviation between IRI-model and the Ilorin drift between 2000 and 0500Â h is 4.37, 2.03, 3.71 and 2.42Â 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 1.27Â m/s in the same order respectively. Annual hmF2 inferred drift over Ilorin during daytime is higher by a factor of â2 and 3 at Jicamarca and IRI model measurements respectively; and by a factor of â5 for both during the night-time period. The limitations in using hmF2 to infer drifts are discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Advances in Space Research - Volume 54, Issue 8, 15 October 2014, Pages 1629-1641
Journal: Advances in Space Research - Volume 54, Issue 8, 15 October 2014, Pages 1629-1641
نویسندگان
J.O. Adeniyi, B.O. Adebesin, I.A. Adimula, O.A. Oladipo, A.O. Olawepo, S.O. Ikubanni, B.W. Reinisch,