Extended main phase of some sudden commencement great geomagnetic storms with double SSCs

Srivastava, Bipin K.; Abbas, Habiba; Rao, D. R. K.; Pathan, B. M.

doi:10.1016/s1364-6826(99)00049-8

Cited by 3 publications

(2 citation statements)

References 9 publications

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“…This type of main phase growth has been recently examined by Kamide et al (1998), who found that for more than 50% of intense storms, the main phase undergoes a two-step growth. Similar type of the D st variations has been also referred to as an extended main phase, and examined in detail by Srivastava et al (1999). Kamide et al (1998) also clarified the solar wind condition for the two-step main phase growth; if a northward excursion occurs during southward B z , and IMF turns southward again, it leads to a well-defined two-step growth in the storm main phase.…”

Section: Discussionmentioning

confidence: 81%

Consequences of the neural network investigation for Dst-AL relationship

2014

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Several recent studies have suggested that most of the D st main phase variations and of the AL variations similarly respond to a certain type of solar wind condition although the processes are independent of each other. This similarity suggests that some consistency between the D st main phase development and AL variations exists, regardless of the existence of causality. In what situations this consistent relationship really exists or collapses has been examined with the technique of an Elman recurrent neural network. The network was trained with the D st and hourly averaged AL indices for 70 storm events from 1967 to 1981, and tested for nine storms that occurred in 1982. The result shows that the D st -AL relationship can be categorized into two types: high correlative mapping for which 80% and more of the D st peak in the main phase is reproduced by AL, and partially correlative mapping where only about a half of the D st peak is reproduced. It is found that whether the correlation is high or partial is determined by whether the D st main phase develops smoothly or with a discontinuity, i.e., for storms having a discontinuity in the main phase, the coherency collapses. The discontinuity in the D st main phase is associated with the rapid southward IMF change after the northward excursion. We suggest that it is this IMF variation to which storms and/or substorms respond in a highly complex manner and that such a complex response can be associated with about a half of the maximum ring current intensity.

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Section: Discussionmentioning

confidence: 81%

Consequences of the neural network investigation for Dst-AL relationship

2014

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“…The solar effect on the magnetic perturbation that occurs during geomagnetic storms has been studied by many scientists (e.g., Sugiura, 1953;Rastogi et al, 1964;Srivastava et al, 1999). India has a unique set of geomagnetic observatories spanning the magnetic equator and the S q focus in a region of the world where the geomagnetic and geographic meridian planes are least separated.…”

Section: Introductionmentioning

confidence: 99%

Fuzzy mathematical model for the analysis of geomagnetic field data

Sridharan¹

2009

Earth Planet Sp

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The Indian network of magnetometers provides an opportunity to examine the pattern of geomagnetic field variations during magnetic storms. In this study, fuzzy transitive closure analysis, which is a powerful technique for pattern recognition, has been employed. The pattern of variation differs at the nonequatorial, equatorial and the observatory situated nearer to the geomagnetic S q focus. The results of the analysis are compared with those of classical cluster analysis. The comparison confirms the validity of applying this model for the analysis of geomagnetic storms. The superiority of fuzzy concepts over the conventional method and the analytical techniques are presented here.

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Studies of the Earth’s Magnetic Field from Peninsular India: Contributions from CSIR-NGRI

Venkateshwarlu

Arora

2021

J Geol Soc India

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Extended main phase of some sudden commencement great geomagnetic storms with double SSCs

Cited by 3 publications

References 9 publications

Consequences of the neural network investigation for Dst-AL relationship

Consequences of the neural network investigation for Dst-AL relationship

Fuzzy mathematical model for the analysis of geomagnetic field data

Studies of the Earth’s Magnetic Field from Peninsular India: Contributions from CSIR-NGRI

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