The Effect of the Heliospheric Current Sheet on Interplanetary Shocks |
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Authors: | Yanqiong Xie Fengsi Wei Changqing Xiang Xueshang Feng |
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Institution: | (1) State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing, 100080, China;(2) Graduate School of the Chinese Academy of Sciences, Beijing, 100049, China;(3) Institute of Meteorology, PLA University of Science and Technology, Nanjing, 211101, China |
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Abstract: | Using 180 interplanetary (IP) shock events associated with coronal mass ejections (CMEs) during 1997 – 2005, we investigate
the influence of the heliospheric current sheet (HCS) upon the propagation and geoeffectiveness of IP shocks. Our preliminary
results are: (1) The majority of CME-driving IP shocks occurred near the HCS. (2) The numbers of shock events and related
geomagnetic storms observed when the Earth and the solar source are located on the same side of the HCS, represented by f
SS and f
SG, respectively, are obviously higher than those when the Earth and the solar source are located on the opposite sides of the
HCS, denoted by f
OS and f
OG, with f
SS/f
OS=126/54, f
SG/f
OG = 91/36. (3) Parameter jumps across the shock fronts for the same-side events are also higher than those for the opposite-side
events, and the stronger shocks (Δ V ≥ 200 km s−1) are mainly attributed to be same-side events, with f
SSh/f
OSh = 28/15, where f
SSh and f
OSh are numbers of stronger shocks which belong to same-side events and opposite-side events, respectively. (4) The level of
the geomagnetic disturbances is higher for the same-side events than for the opposite-side events. The ratio of the number
of intense magnetic storms (Dst < −100) triggered by same-side events to those triggered by opposite-side events is 25/10.
(5) We propose an empirical model to predict the arrival time of the shock at the Earth, whose accuracy is comparable to that
of other prevailing models. These results show that the HCS is an important physical structure, which probably plays an important
role in the propagation of interplanetary shocks and their geoeffectiveness. |
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Keywords: | |
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