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Interplanetary circumstances of quasi-perpendicular interplanetary shocks in 1996-2005


Richardson, IG and Cane, HV, Interplanetary circumstances of quasi-perpendicular interplanetary shocks in 1996-2005, Journal of Geophysical Research-Space Physics, 115, (A07103) EJ ISSN 0148-0227 (2010) [Refereed Article]

DOI: doi:10.1029/2009JA015039


The angle (theta(Bn)) between the normal to an interplanetary shock front and the upstream magnetic field direction, though often thought of as a property "of the shock," is also determined by the configuration of the magnetic field immediately upstream of the shock. We investigate the interplanetary circumstances of 105 near-Earth quasi-perpendicular shocks during 1996-2005 identified by theta(Bn) >= 80 degrees and/ or by evidence of shock drift particle acceleration. Around 87% of these shocks were driven by interplanetary coronal mass ejections (ICMEs); the remainder were probably the forward shocks of corotating interaction regions. For around half of the shocks, the upstream field was approximately perpendicular to the radial direction, either east-west or west-east or highly inclined to the ecliptic. Such field directions will give quasi-perpendicular configurations for radially propagating shocks. Around 30% of the shocks were propagating through, or closely followed, ICMEs at the time of observation. Another quarter were propagating through the heliospheric plasma sheet (HPS), and a further quarter occurred in slow solar wind that did not have characteristics of the HPS. Around 11% were observed in high-speed streams, and 7% in the sheaths following other shocks. The fraction of shocks found in high-speed streams is around a third of that expected based on the fraction of the time when such streams were observed at Earth. Quasi-perpendicular shocks are found traveling through ICMEs around 2-3 times more frequently than expected. In addition, shocks propagating through ICMEs are more likely to have larger values of theta(Bn) than shocks outside ICMEs.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Solar physics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cane, HV (Dr Hilary Cane)
ID Code:70492
Year Published:2010
Web of Science® Times Cited:23
Deposited By:Research Division
Deposited On:2011-06-23
Last Modified:2011-06-26

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