Modeling slow- and fast-moving interplanetary magnetic clouds

Inter-planetary disturbances travel through the inner heliosphere (a range of heliodistances from 1 to 216 AU) at speeds larger than that of the ambient solar wind in about 3 to 4 days. The spike speed of the disturbance near the solar activity can reach a maximum speed of 1,000 or more km/sec. Out of more than 50 interplanetary magnetic clouds of toroidal shape analyzed in [1] using formulas from [2], we select two events from May 1997 and April 1999, with large AP-daily index: 55.9 and 46.8, respectively. The time of the launch and the arrival time of the cloud are from [1]. Solar activity which can be related to known geo-magnetic storms is discussed. The theoretical dynamics model developed in [3] is adopted in such a way that real parameters in solar wind (density of the particles, temperature, and interplanetary B-field magnitude) are taken into account. We compare slow- and fast-moving magnetic clouds and the time of travel of the cloud’s center of mass. In our dynamics model, the magnetic disturbances are driven by three forces gravitational forces, drag forces and diamagnetic forces. Near the Earth’s orbit, the diamagnetic force and drag force are competing.

[1] Marubashi, K., Akiyama, S., Yashiro, S., Gopalswamy, N., Cho, K. -S., Park, Y. -D., Solar Physics, 290(5), 1371-1397, 2015; [2] Romashets and Vandas Journal Geophysical Research 30(20) 2065 2003; [3] Romashets E. P. and M. Vandas, Journal of Geophysical Research, 106, 10615-10624, 2001.