Height‐Integrated Ionospheric Conductances Parameterized By Interplanetary Magnetic Field and Substorm Phase
Jennifer Carter, S. E. Milan, L. J. Paxton, B. J. Anderson, J. W. Gjerloev
Abstract
Abstract An understanding of ionospheric conductances is important for models of large‐scale dynamics in the Earth's magnetosphere. We parameterize height‐integrated Pedersen and Hall conductances in the ionosphere, derived from images of auroral emissions obtained by the Defense Meteorological Satellite Programme low‐altitude orbiting spacecraft, under different interplanetary and solar wind conditions. For the dayside, conductances are parameterized by interplanetary magnetic field clock angle and magnitude, and by season. These dayside conductances are compared to distributions of field‐aligned currents determined from measurements of the Active Magnetosphere and Planetary Electrodynamic Response Experiment. We use these currents to spatially determine a return flow region. We find that the return flow regions exhibit marginally larger conductances than those observed in the polar cap. Conductances in summer exceed those in winter for both the return flow and polar cap regions, on average by a factor of 1.2. On the nightside, we track changes in height‐integrated conductance across the Southern Hemisphere polar regions during an average substorm, following a substorm onset list derived from the SuperMAG database. Mean conductances peak approximately 0.75 hr after substorm onset, with maximum conductances seen in the 23 hr magnetic local time sector.