Table 2.

Major particle populations (subsystems) in the magnetosphere; parameters of the populations can be found in Fig. 2

Plasma population	What and where	Origin	Roles in the system
Ionosphere	Ionized upper atmosphere	Sunlight on atmosphere and electron impact on atmosphere	Supplies plasma to magnetosphere Source of the plasmasphere and warm plasma cloak Dissipates system energy by Joule heating Hinders magnetospheric convection
Magnetosheath	Shocked solar-wind plasma bathing the outer surface of the magnetosphere	Solar wind	Plasma properties govern dayside reconnection rate Supplies solar-wind-origin plasma Transfers momentum into magnetosphere Generates ULF waves
Plasmasphere	Cold ionospheric-origin plasma in the dipolar region	Ionosphere	Provides home for whistler-mode hiss waves Provides home for EMIC waves Feeds drainage plume Feeds back on dayside reconnection
Ion plasma sheet (includes ring current)	Hot ions in magnetotail and dipolar region	Mantle, LLBL, Ionosphere	Diamagnetically distorts magnetic field Drives EMIC waves in dipole Can mass load dayside reconnection rate
Electron plasma sheet	Hot electrons in magnetotail and dipolar region	Solar wind	Home of the aurora and auroral currents Provides enhanced ionization of ionosphere Drives chorus waves May control ionospheric outflows to the warm plasma cloak Seed population for substorm-injected electrons
Electron radiation belt	Relativistic electrons in the dipolar region	Substorm-injected electrons	Energy sink for plasma waves Spacecraft damage Alters atmospheric chemistry
Ion radiation belt	Very energetic protons in dipolar region	Neutron decay, Solar wind Ion plasma sheet	not much is known about the origin and interactions of the outer proton belt
Substorm-injected electrons	Energetic electrons in the dipolar region	Electron plasma sheet	Drives whistler-mode chorus waves Seed population for electron radiation belt
Warm plasma cloak	Cool oxygen-rich plasma in dipolar region	Ionosphere	Mass loading of dayside reconnection rate Controls properties of ULF waves
Low-latitude boundary layer (LLBL)	Solar-wind plasma flowing tailward inside the magnetopause	Magnetosheath	Feeds plasma into the ion and electron plasma sheets
Mantle	Solar-wind plasma and cusp-ionosphere plasma moving into the magnetotail	Magnetosheath	Feeds plasma into the ion and electron plasma sheets Impacts reconnection rate in magnetotail
Plasmaspheric drainage plume	Cold plasma flowing from plasmasphere to dayside magnetopause	Plasmasphere	Loss of plasmasphere Mass loading of dayside reconnection rate Home of EMIC and hiss waves at larger radii than plasmasphere
Atmosphere	Neutral gas gravitationally bound to the Earth		Absorbs electrons and ions from the magnetosphere
Hydrogen geocorona	Neutral hydrogen evaporating off of atmosphere	Atmosphere	Causes charge-exchange loss of ion-plasma-sheet ions Has a charge-exchange interaction with the plasmasphere Is affected by magnetospheric energy input into upper atmosphere

EMIC: electromagnetic ion-cyclotron