Continent-Wide R1/R2 Current System and Ohmic Losses by Broad
Dipolarization-Injection Fronts
Abstract
We employ Magnetospheric Multiscale, Geostationary Operational
Environmental and Los Alamos National Laboratory satellites, as well as
the ground magnetometer networks over Greenland and North America to
study a substorm on 9 August 2016 between 9 and 10 UT.We found that
during the substorm two earthward flows, whose dipolarization-injection
fronts exceeded 6.5 and 4 Earth’s radii (RE) in YGSM, impinged and
rebounded from Earth’s dipolar field lines at L = 6–7 downtail, where L
is the McIlwain number. The impingements and rebounds ended with a
substorm current system of downward R1 and upward R2 currents which grew
to azimuthally cover the whole North American continent. At the fronts,
regions of enhanced negative j·E′ were formed and peaked toward the end
of the impingements. These regions appeared to be conjugate with
eastward moving aurora (along the growth phase arc and together with
eastward drifting energetic electrons at geosynchronous equatorial
orbit), which manifests ionospheric Ohmic losses.