A three‐dimensional (3‐D), time‐dependent, magnetohydrodynamic (MHD) model is used to simulate the interplanetary propagation of a disturbance that started in the low corona via the destabilization of a southern hemisphere helmet‐streamer on April 14, 1994. A severe geomagnetic storm occurred at Earth, and a forward‐reverse shock structure was detected at Ulysses (3.2 AU) at E30°S60°. The model is initiated at 18Rs (where Rs is the solar radius, 6.95 × 10 5 km) within the supersonic and super‐Alfvenic region of the solar wind; hence no consideration is given to the disturbance's evolution from ∼ 1Rs to 18Rs. We refer to the interplanetary disturbance as an interplanetary/coronal mass ejection (ICME) to indicate that it may be relevant to what has been referred to in the literature as a CME but is not related to the flux rope or magnetic cloud that has also received much attention.We find that the 3‐D MHD model, with a simple pressure pulse (suggested by Yohkoh soft Xray observations), provides a satisfactory comparison with the SSC timing at Earth and the Ulysses observations.
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Dryer et al. (1997) studied this question.