Interaction between an interplanetary magnetic cloud and the Earth's magnetosphere: Motions of the bow shock

D. J. Wu, J. K. Chao, and R. P. Lepping

Purple Mountain Observatory, Chinese Academy of Sciences, PRC


An interplanetary magnetic cloud (IMC) is an important solar-terrestrial connection event. It is also an ideal object for the study of solar-terrestrial relations and space weather, because the Earth's space environment can be affected considerably during an IMC passage. An IMC was observed to pass the Earth during October 18-20, 1995. WIND recorded its interplanetary characteristics at ~ 175 RE upstream of the Earth's bow shock, and about 45 minutes later, Geotail detected, again, this IMC, near the Earth's bow shock. Especially, during this IMC passage, Geotail recorded multiple crossings of the bow shock. Using simultaneous, two-satellite data from WIND and Geotail, we analyzed, with a semi-empirical model with two parameters for the bow shock, the bow shock motion caused by the interaction of the IMC with the magnetosphere during its passage. At the same time, we also compared the bow shock motion predicted by the semi-empirical model with the Geotail observations of the bow shock crossing. The results showed that the multiple bow shock crossings observed by Geotail can be explained well by the predicted bow shock motion due to temporal variations of the upstream solar wind parameters.

J. Geophys. Res., Vol 105, A6, 12627-12638, 2000