Abstract
Joule heating deposits a significant amount of energy into the
high-latitude ionosphere and is an important factor in many
magnetosphere-ionosphere-thermosphere coupling processes. We consider
the relationship between localized temperature enhancements in polar cap
measured with the Resolute Bay Incoherent Scatter Radar-North (RISR-N)
and the orientation of the IMF. Based on analysis of 10 years of data,
RISR-N most commonly observes ion heating in the noon sector under
northwards IMF Bz. We interpret heating events in that sector as being
primarily driven by sunwards plasma convection associated with lobe
reconnection. We attempt to model two of the observed temperature
enhancements with a data-driven first principles model of ionospheric
plasma transport and dynamics, but fail to fully reproduce the ion
temperature enhancements. However, evaluating the ion energy equation
using the locally measured ion velocities reproduces the observed ion
temperature enhancements. This result indicates that current techniques
for estimating global plasma convection pattern are not adequately
capturing mesoscale flows in the polar cap, and this can result in
underestimation of the energy deposition into the ionosphere and
thermosphere.