Multi-Instrument Study of Joule Heating in the Polar Cap during Northward Interplanetary Magnetic Field

Recent total electron content measurements made during northward interplanetary magnetic field conditions (IMF) suggest global perturbations in the ionosphere consistent with enhanced energy input from particle precipitation and/or Joule heating. Northward IMF typically results in field-aligned currents at very high latitudes, poleward of the large-scale Region 1 Birkeland currents. We use field-aligned current data from AMPERE to study northern hemisphere Joule heating and particle precipitation during IMF Bz north conditions. The field-aligned current data are used as input to a new version of the ADELPHI auroral electrodynamics model that improves the electric potential specification in the vicinity of the magnetic pole. The associated electric fields are combined with conductances determined from the field-aligned currents to determine the Joule heating rates. The conductances are verified using incoherent scatter radar electron number density measurements from the Resolute Bay Incoherent Scatter Radar (RISR), along with energetic particle and far ultraviolet measurements from the DMSP satellites when available. The combined observations allow for determination of energy input from particle precipitation and Joule heating as a function of altitude during these events. The effects of solar illumination, conductances, and neutral winds on Joule heating rates are also examined. These results help to assess the feasibility of using AMPERE field-aligned current observations to routinely and continuously specify energetic particle and Joule heating energy input in the polar cap.