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Comparative Investigation of the Digisonde‐Derived Electron Density and IRI Profiles at a Station Near the African Magnetic Equator During LowSolar Activity
Author(s) -
Adebiyi S. J.,
Adeniyi J. O.,
Adebesin B. O.,
Ikubanni S. O.,
Adimula I. A.,
Oladipo O. A.,
Olawepo A. O.,
Adekoya B. J.,
Joshua B. W.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2019ja027477
Subject(s) - solstice , daytime , equinox , sunset , ionosphere , tec , sunrise , international reference ionosphere , atmospheric sciences , solar maximum , total electron content , f region , equator , solar minimum , geology , environmental science , meteorology , geodesy , latitude , solar cycle , physics , geophysics , solar wind , quantum mechanics , astronomy , magnetic field
Information about the altitudinal distribution of ionospheric electron density (Ne) in the African equatorial region is very scanty. Such information is vital in modeling of key ionospheric parameters and in solving problems associated with ionospheric effect on the applications that depend on space‐based positioning and navigation systems. For the first time in the region, the entire Ne profile estimated by IRI is evaluated with profile deduced from Digisonde measurements at Ilorin (geog. 8.50°N, 4.50°E; dip. −7.9°) during low solar activity condition. Results obtained indicate marked discrepancies between the two profiles with magnitudes revealing local time and altitudinal and seasonal trends. The largest discrepancies are found between the post‐sunset and sunrise hours regardless of the seasons. IRI underestimates the Ne around the F1 region and is most obvious in September equinox and December solstice with deviation up to −42%. Further, IRI overestimates the Ne around the F2 peak at daytime, mostly in solstices with maximum deviation of 26% at F2 peak. All the three IRI topside models generally underestimate Ne between ~F2 peak height and ~800 km in all seasons except in June solstice. Beyond 800 km, the Digisonde, IRI‐NeQuick, and IRI‐2001 Corr profiles tend to converge, whereas the IRI‐2001 profiles still show marked divergence from the Digisonde profile in all seasons. Overall, the IRI‐NeQuick gives the best topside representation at this station at daytime/nighttime. The comparative analysis of Digisonde‐TEC and GPS‐TEC suggests that the Digisonde alone may not give a reliable estimate of the nighttime topside altitudinal distribution of Ne at this location.