Published online by Cambridge University Press: 25 April 2016
Determination of the large-scale structure of flare-produced disturbances requires either multiple spacecraft observations or an ensemble averaging of single spacecraft observations of a number of events. There is currently some confusion in the results of studies of shock normals derived from spacecraft data. Chao and Lepping (1974) suggest that the average shock shape near 1 AU is essentially spherical while Bavassano et al. (1973) suggest that the disturbance corresponds closely to the shapes predicted in the numerical simulations of de Young and Hundhausen (1971).