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On the Pre‐Magnetic Storm Signatures in NmF2 in Some Equatorial, Low‐ and Mid‐Latitude Stations

Abstract : In this paper, the ionospheric quiet-time disturbances otherwise known as Pre-Magnetic Storm Signatures (PMS) have been studied using the F2-layer peak electron density (NmF2) data obtained from 12 Digisonde/ionosonde stations distributed across equatorial, low and mid-latitudes. The datasets used spans the years 2010–2012. Results from this study reveals strong PMS in NmF2 with percentage deviations (ΔNmF2) ranging from −91% to 500% at the equatorial, low and mid-latitudes, with maxima occurring at the equatorial region. Significant effects on the peak height of the F2-layer (hmF2) were also observed, and they are correlated with the variations in NmF2 particularly at the equatorial station during the PMS. The duration of a PMS is found to be 12–48 h. Although, it was difficult to state clearly the connection between the PMS and the geomagnetic storm that usually follows within 24–48 h; but the NmF2 and hmF2 responses during the PMS were quite similar to those observed during geomagnetic storms. A slight increase in the Solar-wind-plasma speed (>20 km/s) was also observed during PMS. The PMS occur under a southward IMF-Bz, moderate aurora activity (AE ranging from 114 to 560 nT) and quiet ring current (Dst >−10 nT). Therefore, it is pertinent to consider a certain threshold of the aurora indices (AE, AL, and AU) in addition to the Dst, ap, and Kp in the definition of a geomagnetically quiet day. This may eliminate the ambiguity in explaining the ionospheric variability that occurs few days before Sudden Storm Commencement (SSC).
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Contributor : Christine Amory-Mazaudier Connect in order to contact the contributor
Submitted on : Monday, August 30, 2021 - 12:41:09 PM
Last modification on : Friday, October 8, 2021 - 2:44:01 PM


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B. Joshua, J. Adeniyi, C. Amory‐mazaudier, S. Adebiyi. On the Pre‐Magnetic Storm Signatures in NmF2 in Some Equatorial, Low‐ and Mid‐Latitude Stations. Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2021, 126 (8), pp.e2021JA029459. ⟨10.1029/2021JA029459⟩. ⟨hal-03328776⟩



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