Tail substorm dynamics captured by HENA

Ions drifting in from nightside filling the plasmasheet

Dipolarization:

Ions accelerated earthward evacuating plasmasheet densities

Accelerated ions reach lower altitudes.

Auroral onset

Plasmasheet starts refilling.

Edge moving out.

Plasmasheet restored.

• HENA observes ENAs coming from 12 Re in the magnetotail.
• The observed tail propagates Earthward at substorm dipolarization.
• Correlated with auroral substorm onset.
• So far observed for 4 October 2000 and 19 September 2000 storm.

DUSK

DAWN

SUN