Timescales for the penetration of IMF By into the Earth's magnetotail

Browett, S.D., Fear, R.C., Grocott, A. and Milan, S.E. (2016) Timescales for the penetration of IMF By into the Earth's magnetotail Journal of Geophysical Research: Space Physics, 122, pp. 579-593. (doi:10.1002/2016JA023198).


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Previous studies have shown there is a correlation between the By component of the interplanetary magnetic field (IMF) and the By component observed in the magnetotail lobe and in the plasma sheet. However, studies of the effect of IMF By on several magnetospheric processes have indicated that the By component in the tail should depend more strongly on the recent history of the IMF By rather than on the simultaneous measurements of the IMF. Estimates of this timescale vary from ?15 minutes to ?4 hours. We present a statistical study of how promptly the IMF By component is transferred into the neutral sheet, based on Cluster observations of the neutral sheet from 2001 to 2008, and solar wind data from the OMNI database. 5982 neutral sheet crossings during this interval were identified, and starting with the correlation between instantaneous measurements of the IMF and the magnetotail (recently reported by Cao et al. [2014]), we vary the time delay applied to the solar wind data. Our results suggest a bimodal distribution with peaks at ?1.5 and ?3 hours. The relative strength of each peak appears to be well controlled by: the sign of the IMF Bz component with peaks being observed at 1 hour of lag time for southward IMF and up to 5 hours for northward IMF conditions, and the magnitude of the solar wind velocity with peaks at 2 hours of lag time for fast solar wind and 4 hours for slow solar wind conditions.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1002/2016JA023198
ISSNs: 2169-9380 (print)
Organisations: Astronomy Group
ePrint ID: 404300
Date :
Date Event
17 November 2016Accepted/In Press
22 November 2016e-pub ahead of print
23 January 2017Published
Date Deposited: 05 Jan 2017 14:22
Last Modified: 17 Apr 2017 00:39
Further Information:Google Scholar
URI: http://eprints.soton.ac.uk/id/eprint/404300

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