Investigation of Ionospheric Response to Geomagnetic Storms over a Low Latitude Station, Ile-Ife, Nigeria

Jimoh, Oluwaseyi; Yesufu, Thomas Kokumo; Ariyibi, Emmanuel A.

doi:10.1515/acgeo-2016-0013

Cited by 10 publications

(6 citation statements)

References 38 publications

(41 reference statements)

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“…Bagiya et al [19] in their study on geomagnetic storm of August 24, 2005 using GPS data from Rajkot station (22.29°N, 70.74°E); they observed that, TECv enhancement is due to prompt penetration of electric fields during the storm day and thermospheric composition changes and disturbance dynamo electric fields on the preceding recovery day. Similar results were also reported by Jimoh et al [20] on their study on investigation of ionospheric response to geomagnetic storms over a low latitude station, Ile-Ife, Nigeria. They attributed this with the high energy input at high latitudes that produces traveling ionospheric disturbances (TIDs).…”

Section: Discussionsupporting

confidence: 90%

Ionospheric TEC Response to Geomagnetic Storms Occurred on 15-20 March 2013 and 2015 over the Eastern Africa Region

Sulungu¹,

Uiso²

2019

AJESE

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In this paper we present characteristics of the ionosphere over eastern Africa region in response to two geomagnetic storms of March 2013 and March 2015 that occurred at the same date and time but with different intensities. Ionospheric TEC has been derived from the IGS network of ground based dual-frequency GPS receivers from four stations, namely Eldoret (0.29°N, 35.29°E), Dodoma (6.19°S, 35.75°E), Malindi (2.99°S, 40.19°E) and Mtwara (10.26°S, 40.17°E) within the Eastern Africa region. The interplanetary magnetic field (IMF) Bz and corresponding Dst index, solar wind speed (Vsw) and density (Np) were used to represent the evolution of the storm events. Our results showed that, the behavior of the ionosphere over eastern Africa region during the two geomagnetic storms was similar. During both storms the main phases occurred on 17 th of March. However, the main phase of the storm in 2015 had more intensity than that of 2013 but the same duration, and they were followed by a long-duration slow recovery with values that did not return to levels prior to the onset of the storm. The enhancement and reduction of TECv were observed at almost all stations at different times. The results from both storms also show that, there was a pre-reversal enhancement especially at stations that lie close to the equatorial region compared to the stations far from the equatorial region.

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Section: Discussionsupporting

confidence: 90%

Ionospheric TEC Response to Geomagnetic Storms Occurred on 15-20 March 2013 and 2015 over the Eastern Africa Region

Sulungu¹,

Uiso²

2019

AJESE

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“…In the absence of electric field measurements, sudden increase (decrease) in AE index and abrupt decrease (increase) in Dst index are good indicators to determine the strength, polarities, and time of penetration of electric fields into the equatorial and low latitudes (Abdu, ; Fejer & Scherliess, ; Huang, ; Huang et al, ; Tulasi Ram et al, ). Besides the rate of Dst ( Dst / dt ) is also a good proxy that have been used in the past to serve this purpose (Jain et al, ; Jimoh et al, ; Tulasi Ram et al, ). The AE in Figure a had a sudden increase from 1,400 to 2,400 nT and Dst / dt showed a rapid decrease (~41 nT/hr) at ~2330 UT on 7 September, which suggests that the southward turning of IMF‐ B z with minimum value of ~−30 nT created the undershielding condition that gave rise to PPEF at the low latitudes around 2330 UT.…”

Section: Discussionmentioning

confidence: 99%

“…Journal of Geophysical Research: Space Physics Ram et al, 2008). Besides the rate of Dst (Dst/dt) is also a good proxy that have been used in the past to serve this purpose (Jain et al, 2010;Jimoh et al, 2016;Tulasi Ram et al, 2008). The AE in Figure 1a had a sudden increase from 1,400 to 2,400 nT and Dst/dt showed a rapid decrease (~41 nT/hr) at~2330 UT on 7 September, which suggests that the southward turning of IMF-B z with minimum value of~−30 nT created the undershielding condition that gave rise to PPEF at the low latitudes around 2330 UT.…”

Section: 1029/2019ja026590mentioning

confidence: 99%

“…During a geomagnetic storm, the disturbed ionospheric variabilities are mainly due to alterations in the chemical compositions, dynamic and electrodynamic processes during the different phases of the storm (e.g., Jimoh et al, 2016;Lei et al, 2008;Wang et al, 2010). Owing to the large difference in the electron density of the background ionosphere and the effectiveness of the geomagnetic storm drivers between the day and night sectors, differences exist in the observed storm time effects during both sectors, among which are modification/reinforcement of EIA and the enhancement/inhibition of nighttime ionospheric irregularities.…”

Section: Introductionmentioning

confidence: 99%

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Topside Ionospheric Conditions During the 7–8 September 2017 Geomagnetic Storm

et al. 2019

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The uplooking total electron contents (TECs) from the GRACE, SWARM-A, TerraSAR-X, andMetOp-A satellites and in situ electron density (Ne) from SWARM-A were utilized to investigate the topside ionospheric conditions during the 7-8 September 2017 geomagnetic storm. The rate of TEC index (ROTI) and rate of density index (RODI), which are derivative indices of TEC and Ne, respectively, were also used to characterize the topside ionospheric irregularities. The main results of this study are as follows: (1) There were significant enhancements seen in the uplooking TEC during the first main phase of the storm. (2) The uplooking TEC did not show unusual enhancement at the morning and evening local times in the Asian-Australian sector during the recovery phase of the storm. (3) Prominent TEC hemispheric asymmetry at the middle and high latitudes was observed at both day and night sectors. (4) Long-duration recovery of topside TEC with respect to the prestorm condition was also detected in this event. (5) Nighttime ROTI enhancements were presented in a wide latitudinal range from the equator to the poles during the main phases of the storm. (6) The ionospheric electric field disturbances associated with IMF-B z fluctuations probably played a very important role in triggering ionospheric irregularities during the relatively weak geomagnetic activity on 7 September, which implies that ionospheric irregularities do not necessarily occur under the severe geomagnetic conditions only.Key Points:• Long-duration depletion of topside TEC recovery was observed during the morning and evening local times in this event • Enhancements of ionospheric irregularities were presented at night with wide latitudinal range during the two main phases of the storm • Ionospheric electric field disturbances due to B z fluctuations probably triggered topside ionospheric irregularities before the main phases

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“…Geomagnetic storms usually comprise of three phases: initial, main, and recovery phases [6,11]. Different processes and interactions are at play, depending on the prevalent geophysical and interplanetary conditions during each phase of a geomagnetic storm [12][13][14][15][16][17][18]. The mechanisms responsible for total electron content (TEC) enhancements during the initial and main phases are widely reported [8,[19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Daytime Total Electron Content Enhancements over the Asian-Australian Sector Observed from the Beidou Geostationary Satellite during 2016–2018

2020

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This study focused on the investigation of daytime positive ionospheric disturbances and the recurrence of total electron content (TEC) enhancements. TEC data derived from the Beidou geostationary satellite over the Asian-Australian sector were used to study the occurrence of TEC enhancements during 2016–2018. The occurrence of TEC enhancements under quiet geomagnetic condition was analyzed. Furthermore, the occurrence of TEC enhancements during different geomagnetic storm phases was considered to address the question that relates to the recurrence of TEC enhancements during the recovery phase of geomagnetic storms. The seasonal variation of TEC enhancements displayed equinoctial and solstitial peaks at the middle and low latitudes respectively. Besides, there was no evident systematic latitudinal dependence in the occurrence of TEC enhancements, albeit at the equatorial station, nearly no TEC enhancement was observed under Kp < 3. Meanwhile, the occurrences during the main phases of the geomagnetic storms were significantly above the TEC enhancement baselines except at HKWS. The prominence of TEC enhancements during the main phase in comparison with the initial and recovery phases could be attributed to the effects of prompt penetration electric fields and equator-ward neutral winds. Moreover, the pattern of TEC enhancements during the storm recovery indicates the effects of chemical composition changes, winds, and the possible modulation from the lower atmospheric forcing.

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Investigation of Ionospheric Response to Geomagnetic Storms over a Low Latitude Station, Ile-Ife, Nigeria

Cited by 10 publications

References 38 publications

Ionospheric TEC Response to Geomagnetic Storms Occurred on 15-20 March 2013 and 2015 over the Eastern Africa Region

Ionospheric TEC Response to Geomagnetic Storms Occurred on 15-20 March 2013 and 2015 over the Eastern Africa Region

Topside Ionospheric Conditions During the 7–8 September 2017 Geomagnetic Storm

Investigation of Daytime Total Electron Content Enhancements over the Asian-Australian Sector Observed from the Beidou Geostationary Satellite during 2016–2018

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