Observations of Energetic Storm Particles: An Overview

A Quarter Century ofWindSpacecraft Discoveries

“…ESP events are typically classified into the following types depending on their temporal profile: spike, rise, step, flat and complex (Lario et al., 2003 ; Tsurutani & Lin, 1985 ). There is no simple relationship between the presence/absence and type of ESP events and shock parameters, such as speed, Mach number, or shock normal angle (Cohen, 2006 ). To understand how the acceleration of particles varies along the shock front, ESP measurements made by Wind and ACE of the same events were compared, when Wind was in prograde or petal orbits.…”

Unrestricted Solar Energetic Particle Access to the Moon While Within the Terrestrial Magnetotail

“…The ICME associated with this June event did not directly impact Earth; see, for example, the Richardson and Cane ICME list (Richardson & Cane, 2010) or the Kasper and Stevens shock list. Nevertheless, Figure 1c shows that Wind clearly observed a broad signature of "energetic storm particles" (SEPs accelerated locally by a passing ICME; see Cohen, 2006) beginning near 12:00 on 23 June and lasting ∼24 hr, with all but the highest SST energy channel displaying an enhanced differential energy flux. Panels 1d and 1f illustrate that a nearly identical enhancement was observed by the ARTEMIS SSTs at energies 100 keV ≲ E ≲ 1 MeV during this time.…”

The First Ground Level Enhancement Seen on Three Planetary Surfaces: Earth, Moon, and Mars

“…The identified in-situ arrivals of CME2 and CME8 (orange lines) are followed by enhanced flux of protons with energy below 10 MeV, especially upon CME8's arrival which corresponds to a much stronger in-situ shock (Li et al, 2022). These so-called energetic storm particles (ESPs) are believed to be accelerated by interplanetary shocks as they propagate outward (C. M. Cohen, 2006).…”