The electron precipitation that is caused by inward convection driven by the cross-tail electric field is found to be insufficient to account for the aurora during a substorm, thereby requiring scattering or diffusion into the loss cone in order to account for the aurora that occurs during substorm expansion. Since it has also been found that discrete arcs can be attributed to scattering into the loss cone inside the auroral electron acceleration region, an auroral substorm can therefore be attributed to inward convection driven by the cross-tail electric field, followed by scattering into the loss cone inside the auroral electron acceleration region. ¿ 1998 American Geophysical Union