Flare-generated shock evolution and geomagnetic storms during the 'Halloween 2003 epoch': 29 October to 2 November

[1] The October/November 2003 (“Halloween 2003”) epoch of intense solar flares provided an opportunity to test the results of earlier parametric 1.5 MHD studies of interacting interplanetary shock waves. These preliminary studies used an adaptive numerical grid that made it possible to identify products of these interactions. During 28 October to 2 November 2003, three shocks generated by four solar flares were observed at the L1 libration point by ACE/SWEPAM/SWICS/MAG. Two very distinct geomagnetic storms, associated with two of these flares (X17/4B and X10/2B), rank as two of the largest storms of solar cycle 23. The purpose of this paper is to present the use of an adaptive grid 1.5-dimensional MHD model that is initiated at the solar surface to study in detail the three shocks observed at L1 that were generated by the four solar flares. Accordingly, four separate pressure pulses, at the appropriate times and with different strengths and duration, determined via a trial and error procedure, are introduced on the Sun to mimic the four flares. The results show that the simulated solar wind velocity temporal profiles successfully matched the observations at L1. The major objective, to demonstrate the detailed nature of interacting shocks and some of their products after origination from closely spaced solar events, is achieved. In addition, the MHD model is able to suggest the solar sources that are associated with specific geomagnetic storms at Earth.