Spatial Variations in Disturbance Ionospheric Currents—Inference From 12 Geomagnetic Storms

Bulusu, Jayashree; Archana, R. K.; Arora, Kusumita

doi:10.1029/2019ja027718

Cited by 5 publications

(3 citation statements)

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“…These sites are situated along 72°, 77°, and 93°E, and the EEJ are extracted from these sites using ABG, Hyderabad (HYB), and Portblair (PBR), respectively. Observations from these sites provided a valuable insight into the spatial and temporal characteristics of the quiet time and disturbed time EEJ and CEJ in the Indian sector (Archana et al, 2018;Bulusu et al, 2018Bulusu et al, , 2020Chandrasekhar et al, 2014aChandrasekhar et al, , 2014bChandrasekhar et al, , 2017. All these earlier studies on EEJ and CEJ from the Indian sector used Sq data only from the northern hemisphere for the extraction of EEJ.…”

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confidence: 99%

Re‐Visiting EEJ and CEJ Occurrences Pattern Under the Influence of Sq Variations of Both Hemispheres

2023

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The present study investigated the variability in Equatorial electrojet (EEJ) and Counter electrojet (CEJ) extracted at the Indian equatorial station Tirunelveli (TIR) using low‐latitude geomagnetic conjugate sites, Hyderabad (HYB) and GAN Island (GAN) from the northern and southern hemispheres respectively over a period of 5 years. A significant difference in the amplitudes, of more than 10 nT for 43% of the days, is observed when the TIR‐HYB pair and the TIR‐GAN pair are used. Occurrence of CEJs are 60% more when the TIR‐GAN pair is considered. A correlation coefficient of 0.9 is obtained between the monthly mean peaks of diurnal variations in H between TIR and GAN; this correlation coefficient is 0.66 between TIR and HYB. The correlation coefficients from the first principal components of H, at these sites show variability with seasons; the correlation observed between TIR and GAN is higher than that between TIR‐HYB for all seasons except northern winter. This indicates the coupling of EEJ with Sq of both northern or southern hemispheres with varying extents. The present study highlights that the extraction of EEJ/CEJ using Sq from only one hemisphere will lead to biased estimates; even a small difference in the seasonal pattern of ∆H at equatorial and low latitude sites can result in the over/under‐estimation of EEJ and hence CEJ.

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Re‐Visiting EEJ and CEJ Occurrences Pattern Under the Influence of Sq Variations of Both Hemispheres

2023

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“…The current system in the ionosphere such as the ionospheric disturbance dynamo (Ddyn) can be affected by solar wind disturbances during geomagnetic storm events. The expression of the ionospheric disturbance dynamo (Ddyn) is represented as follows (Le & Amory-Mazaudier 2005;Bulusu et al 2020)…”

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confidence: 99%

“…During these geomagnetically active periods, the thermosphere winds produced in the auroral zone extend toward mid and low latitudes, thereby driving an ionospheric disturbance dynamo (Ddyn) (Blanc & Richmond 1980;Younas et al 2021). The Ddyn effect caused by a geomagnetic storm can be observed using geomagnetic data (Le & Amory-Mazaudier 2005;Bulusu et al 2020).…”

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confidence: 99%

A Comprehensive Classification and Analysis of Geomagnetic Storms Over Solar Cycle 24

Raja Halim Shah,

Abdul Hamid,

Abdullah

et al. 2024

Res. Astron. Astrophys.

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A geomagnetic storm is a global disturbance of Earth’s magnetosphere, occurring as a result of the interaction with magnetic plasma ejected from the Sun. Despite considerable research, a comprehensive classification of storms for a complete solar cycle has not yet been fully developed, as most previous studies have been limited to specific storm types. This study, therefore, attempted to present complete statistics for solar cycle 24, detailing the occurrence of geomagnetic storm events and classifying them by type of intensity (moderate, intense, and severe), type of complete interval (normal or complex), duration of the recovery phase (rapid or long), and the number of steps in the storm’s development. The analysis applied data from ground-based magnetometers, which measured the Dst index as provided by the World Data Center for Geomagnetism, Kyoto, Japan. This study identified 211 storm events, comprising moderate (177 events), intense (33 events), and severe (1 event) types. About 36% of ICME and 23% of CIR are found to be geoeffective, that caused geomagnetic storms. Up to four-step development of geomagnetic storms was exhibited during the main phase for this solar cycle. Analysis showed the geomagnetic storms developed one or more steps in the main phase, which were probably related to the driver that triggered the geomagnetic storms. A case study was additionally conducted to observe the variations of the ionospheric disturbance dynamo (Ddyn) phenomenon that resulted from the geomagnetic storm event of July 13, 2015. The attenuation of the Ddyn in the equatorial region was analysed using the H component of geomagnetic field data from stations in the Asian sector (Malaysia and India). The variations in the Ddyn signatures were observed at both stations, with the TIR station (India) showing higher intensity than the LKW station (Malaysia).

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A Case Study on Magnetic Signature of Ionospheric Disturbance Dynamo During an Intense Geomagnetic Storm on 6 August 2011

Shah,

Hamid,

Abdullah

et al. 2024

Springer Proceedings in Physics

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Spatial Variations in Disturbance Ionospheric Currents—Inference From 12 Geomagnetic Storms

Cited by 5 publications

References 35 publications

Re‐Visiting EEJ and CEJ Occurrences Pattern Under the Influence of Sq Variations of Both Hemispheres

Re‐Visiting EEJ and CEJ Occurrences Pattern Under the Influence of Sq Variations of Both Hemispheres

A Comprehensive Classification and Analysis of Geomagnetic Storms Over Solar Cycle 24

A Case Study on Magnetic Signature of Ionospheric Disturbance Dynamo During an Intense Geomagnetic Storm on 6 August 2011

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