Multi-fluid/multi-scale simulations of the February 26, 2008 substorm

3D multi-fluid/multi-scale simulations are used to study the morphology and timing of the February 26, 2008 substorm. This event represents an internally triggered substorm. For this event, substorm onset is triggered by an injection of plasma into the plasma sheet with an enhanced concentration of oxygen ions. The arrival of a rotation in the IMF triggers a psuedo-breakup as it propagates past the subsolar point, initiating local and patchy reconnection. Substorm onset occurs after the enhancement in oxygen ions arrives at the plasma sheet and initiates cross-tail reconnection. The time delay between psuedo-breakup and substorm onset is approximately 35 minutes, with the substorm lasting approximately an hour. Simulation results are validated with observations from THEMIS. The simulation results show that the oxygen enhancement is highly asymmetric, primarily in the southern hemisphere, near local midnight, highlighting the difficulty in observing an internal triggering mechanism with satellites.