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CME - driven shocks and the associated sudden commencements/sudden impulses

Veenadhari, B. and Selvakumaran, R. and Singh, R. and Maurya, A.K. and Gopalswamy, N. and Kumar, Sushil and Kikuchi, T. (2012) CME - driven shocks and the associated sudden commencements/sudden impulses. Journal of Geophysical Research (Space Physics), 117 (A04210). pp. 1-11. ISSN 0148-0227

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Interplanetary shocks (IP) are mainly responsible for the sudden compression of magnetosphere causing storm sudden commencement (SC) and sudden impulses (SI) which are detected by ground based magnetometers. Based on the list of 222 IP shocks compiled by Gopalswamy et al. [2010], we have investigated the dependence of SC/SIs amplitudes on the speed of the Coronal Mass Ejections (CMEs) that drive the shocks near the Sun as well as in the interplanetary medium. We find that about 91% of the IP shocks were associated with SC/SIs. The average speed of the SC/SI associated CMEs is 1015km/s, which is almost a factor of 2 higher than the general CME speed. When the shocks were grouped according to their ability to produce type II radio burst in the interplanetary medium, we find that the radio-loud (RL) shocks produce a much larger SC/SI amplitude (average ~32 nT) compared to the radio-quiet (RQ) shocks (average ~ 19 nT). Clearly, RL shocks are more effective in producing SC/SIs than the RQ shocks. We also divided the IP shocks according to the type of IP counterpart of CMEs (ICMEs): magnetic clouds (MCs) and non-magnetic clouds. We find that the MC- associated shock speeds are better correlated with SC/SI amplitudes than those associated with non-MC ejecta. The SC/SI amplitudes are also higher for MCs than Ejectas (EJs). Our results show that RL and RQ type of shocks are important parameters in producing the SC/SI amplitude.

Item Type: Journal Article
Additional Information: IF 3.303
Subjects: Q Science > QC Physics
Divisions: Faculty of Science, Technology and Environment (FSTE) > School of Engineering and Physics
Depositing User: Ms Shalni Sanjana
Date Deposited: 18 Jul 2012 08:06
Last Modified: 16 Jan 2017 03:01

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