2.3 ExB
drifts
The magnetospheric potential is mapped onto SAMI3’s magnetic apex
coordinates and superposed with the internal wind-driven dynamo. The
spatial derivative of this combined potential is calculated to find the
electric field E . The electric field producesE xB ion drifts in the model, resulting in predictions
of largely photo-ionized F-region plasma flowing into the polar cap from
the dayside.
3. Results
Over the course of the experiment, the most intense period of
disturbances occurred in the later hours of 23 May 2014, between 19 –
22 UT. Relevant DMSP passes during this period were identified and used
to assess the accuracy of the AMPERE-derived potentials. The flagged
“good” data from UT Dallas were decimated and mapped to a geographic
reference frame before plotting. Results of three passes (two from F16
and one from F18, spaced by ~2 hours total) are shown in
Figure 4, with the pass times indicated in each subplot. Note that these
(and subsequent) plots are in geographic coordinates and so the subsolar
point is in the bottom-left. The potentials closest to the center of
each pass are shown. In these cases there was no great variation between
timesteps across each pass, and the three cases are broadly consistent
with each other. In all cases, DMSP velocities and AMPERE-derived
potentials show close agreement in the evening cell (negative
potential), where the velocity turning points match the location of the
minimum potential, and the velocities line up well to the potential
contours. However there are some discrepancies in the morning cell
(shown in blue), where the DMSP data do not show the turning points that
would be expected from the modeled potential.