The Unpredictability of Killer Electrons

They have a 24-48 hour typical rise time from a SW disturbance (shock, Dst storm, etc.) But can be as short as 8 hr (Jan 97) or as long as 72 hours.
The intensity roughly follows a solar cycle dependence but can vary by 3 orders of magnitude
The spectral hardness generally increases during the storm, but exhibits a “knee” that whose cutoff strongly depends on the unpredictable magnitude
Best correlation with Vsw (70%) but Bz or n_sw ruins it. Neither mechanical nor electrical SW driver

They have a 24-48 hour typical rise time from a SW disturbance (shock, Dst storm, etc.) But can be as short as 8 hr (Jan 97) or as long as 72 hours.