Role of beam pattern selection and a "keogram" program for EISCAT_3D

by Spencer Mark Hatch (Universitetet i Bergen)

We present results from some test experiments for EISCAT_3D based on synthetic
measurements. The first experiment is designed to determine the relationship
between beam pattern selection and the resolution (minimum resolvable scale
size) of plasma convection patterns reconstructed from E3D measurements, while
the second is designed to investigate the feasibility a "keogram" EISCAT_3D
experiment for 2.5D monitoring and reconstruction of auroral arc dynamics
between 67° and 68° magnetic latitude with uncertainties of less than 100 m/s
in estimates of plasma convection perpendicular to the background magnetic
field. We find with the first experiment that different beam patterns covering
approximately the same area do not heavily alter the predicted convection
variances (posterior model covariance projected into convection space).
However, we find that beam pattern selection does play a role in the overall
resolution of the reconstructed convection pattern. Our results constitute a
reference point for considerations around beam pattern selection.

The second experiment is optimized for determining the motion of auroral arcs
relative to plasma convection. We show that it may be possible to obtain a
reconstruction of ionospheric convection with uncertainties as low as 50 m/s
during winter conditions, and 25 m/s during summer conditions, given a beam
pattern consisting of 40 beams integrated over 5 min (7.5 s per beam).