Errors associated with 2D representations of high-latitude ionosphere-thermosphere electrodynamics

One of the great challenges of studying the coupled ionosphere-thermosphere system is the difficulty of making distributed in situ measurements simultaneously. Beginning with Birkeland's (1908) pioneering study of ionospheric currents via equivalent currents, many investigations of the complex, coupled, three-dimensional ionosphere-thermosphere system represent this system as a slab or thin shell either out of expedience or necessity. Almost all existing methods for assimilative reconstruction of ionosphere-thermosphere electrodynamics are based on such thin-shell representations. In this study, we use rocket-based measurements of neutral wind profiles and incoherent scatter radar measurements to directly calculate central height-integrated quantities in IT electrodynamics (perpendicular current, Joule heating, Hall and Pedersen conductance) and compare with estimates based on height-integrated quantities derived from the height-integrated Ohm's law and the expression for height-integrated Joule heating. It is shown that when an appropriate estimate of the neutral wind is included, estimates of these height-integrated quantities lie within ~20% of their true values. When the neutral wind is ignored (i.e., assumed to be zero in Earth's corotating frame of reference) estimates differ from their true values by as much as 100%.