A comparison of auroral oval proxies with the boundaries of the auroral
electrojets
Abstract
The boundaries of the auroral oval and auroral electrojets are an
important source of information for understanding the coupling between
the solar wind and the near-earth plasma environment. Of these two types
of boundaries the auroral electrojet boundaries have received
comparatively little attention, and even less attention has been given
to the connection between the two. Here we introduce a technique for
estimating the electrojet boundaries, and other properties such as total
current and peak current, from 1-D latitudinal profiles of the eastward
component of equivalent current sheet density. We apply this technique
to a preexisting database of such currents along the 105◦ magnetic
meridian producing a total of eleven years of 1 minute resolution
electrojet boundaries during the period 2000–2020. Using statistics and
conjunction events we compare our electrojet boundary dataset with an
existing electrojet boundary dataset, based on Swarm satellite
measurements, and auroral oval proxies based on particle precipitation
and field aligned currents. This allows us to validate our dataset and
investigate the feasibility of an auroral oval proxy based on electrojet
boundaries. Through this investigation we find the proton precipitation
auroral oval is a closer match with the electrojet boundaries. However,
the bimodal nature of the electrojet boundaries as we approach the noon
and midnight discontinuities makes an average electrojet oval poorly
defined. With this and the direct comparisons differing from the
statistics, defining the proton auroral oval from electrojet boundaries
across all local and universal times is challenging.