A quantitative comparison of high latitude electric field models during
a large geomagnetic storm
Abstract
Models of the high-latitude ionospheric electric field are commonly used
to specify the magnetospheric forcing in thermosphere or whole
atmosphere models. The use of decades-old models based on spacecraft
data is still widespread. Currently the Heelis and Weimer climatology
models are most commonly used but it is possible a more recent electric
field model could improve forecasting functionality. Modern electric
field models, derived from radar data, have been developed to
incorporate advances in data availability. It is expected that
climatologies based on this larger and up-to-date dataset will better
represent the high latitude ionosphere and improve forecasting
abilities. An example of two such models, which have been developed
using line-of-sight velocity measurements from the Super Dual Auroral
Radar Network (SuperDARN) are the Thomas and Shepherd model (TS18), and
the Time-Variable Ionospheric Electric Field model (TiVIE). Here we
compare the outputs of these electric field models during the September
2017 storm, covering a range of solar wind and interplanetary magnetic
field (IMF) conditions. We explore the relationships between the IMF
conditions and the model output parameters such as transpolar voltage,
the polar cap size and the lower latitude boundary of convection. We
find that the electric potential and field parameters from the
spacecraft-based models have a significantly higher magnitude than the
SuperDARN-based models. We discuss the similarities and differences in
topology and magnitude for each model.