Ionospheric Response to Intense Geomagnetic Storms and Pre-storm

R.F. Oloruntola, A.K. Ogundele, A.F. Akinfoyeku and S.M.A. Shittu

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Received: October 25, 2019       Accepted: December 18, 2019

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Abstract: In this study, the investigation of the ionospheric response to the geomagnetic and interplanetary, pre-storm and storm phenomena was concerned with variation in foF2 during Oct. 19-23, 2001 covering the three phases of the storm. The storm was chosen on the criteria of its intensity and also it is a double step storm. Analysis of the changes in foF2 was conducted using a normalized deviation of critical frequency (δ(foF2)) on the ionosphere of 3 low and 6 mid-latitude stations from 3 sectors of the earth ionosphere. Analysis of a vertical error bar onδfoF2 was also used to investigate the vivid effect of positive and negative storm on the aforementioned parts of the ionosphere. The upper error bar represents the positive storm while the lower error bar presents the negative storm. The result of the study showed that the enormity of Bz turning into southward from northward direction and the variation in F2 layer parameter at the time of geomagnetic storm strongly depends on the intensity of the storm. There was no significant difference between the ionospheric F2 response of low and middle latitude ionosphere any newly burst of storm activity is associated with a newly generated disturbance at the ionospheric F2 layer of the ionosonde stations. The pre-storm period was preceded by intense positive and negative ionospheric storms. Furthermore, the variations in ionospheric F2 in the pre-storm period suggest the impending large ionospheric disturbances at the main phase and increase ionospheric variation exceeding the main phase signified the storm recovery. Also, the record intense ionospheric storm was recorded at the initial phase despite the low geomagnetic storm activity in the period. Correspondingly, the error bar showed clearly the contribution of both negative and positive storm to the stations along the same narrow longitude.

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