Dissecting Earth’s Magnetosphere: 3D Energy Transport in a Simulation of
a Real Storm Event
Abstract
We present new analysis methods of 3D MHD output data from the Space
Weather Modeling Framework during a simulated storm event. Earth’s
magnetosphere is identified in the simulation domain and divided based
on magnetic topology and the bounding magnetopause definition. Volume
energy contents and surface energy fluxes are analyzed for each
subregion to track the energy transport in the system as the driving
solar wind conditions change. Two energy pathways are revealed, one
external and one internal. The external pathway between the
magnetosheath and magnetosphere has magnetic energy flux entering the
lobes and escaping through the closed field region and is consistent
with previous work and theory. The internal pathway, which has never
been studied in this manner, reveals magnetically dominated energy
recirculating between open and closed field lines. The energy enters the
lobes across the dayside magnetospheric cusps and escapes the lobes
through the nightside plasmasheet boundary layer. This internal
circulation directly controls the energy content in the lobes and the
partitioning of the total energy between lobes and closed field line
regions. Qualitative analysis of four-field junction neighborhoods
indicate the internal circulation pathway is controlled via the
reconnection X-line(s), and by extension, the IMF orientation. These
results allow us to make clear and quantifiable arguments about the
energy dynamics of Earth’s magnetosphere, and the role of the lobes as
an expandable reservoir that cannot retain energy for long periods of
time but can grow and shrink in energy content due to mismatch between
incoming and outgoing energy flux.