2 research outputs found
Studies of magnetotail dynamics and energy evolution during substorms using MHD simulations
We examine the distribution and propagation of energy in the plasma sheet
and lobes using observations and simulations for three substorms. The
substorms occurred on 9 March 1995, 10 December 1996, and 27 August 2001
and have been simulated using the Lyon-Fedder-Mobarry magneto-hydrodynamic
code. All three events occur over North America and show a clear substorm
current wedge over the ground magnetometer chains of Alaska, Canada, and
Greenland. The three simulations show the thinning of the plasma sheet
during the growth phase of the event and an increase in the relative amount
of thermal energy due to the compression of the plasma sheet. Generally, the
total lobe energy, polar cap flux, and lobe magnetic field strength
simultaneously increase during the growth phase, and polar cap flux and
total lobe energy only start dropping at substorm onset, as measured by the
CANOPUS magnetometer chain. Starting at time of onset and continuing
throughout the expansion phase a transfer of magnetic energy from the lobes
into the plasma sheet occurs, with the increase in the plasma sheet energy
ranging from 30β40% of the energy that is released from the lobes