Fig. 19
From: Earth-affecting solar transients: a review of progresses in solar cycle 24
The two-class paradigm for SEP events in which (a) gradual SEP events are produced as a result of diffusive acceleration by large-scale CME-driven coronal and interplanetary (IP) shock waves. The accelerated SEPs populate Interplanetary Magnetic Field (IMF) lines over a wide range of longitudes. (b) Impulsive SEP events are attributed to acceleration during magnetic reconnection in solar flares and observed when the observer is magnetically connected to the flare site. Intensity-time profiles of electrons and protons in (c) gradual and (d) impulsive SEP events. (Reproduced from Desai and Giacalone 2016, after Reames 1999)