High-latitude plasma convection based on SuperDARN observations and the
locally divergence free criterion
- William A. Bristow,
- Larry R. Lyons,
- Yukitoshi (Toshi) Nishimura,
- Simon George Shepherd,
- Eric F. Donovan
Abstract
A new technique for estimating the global-scale pattern of
magnetospheric convection in the ionosphere is presented. The technique
uses the SuperDARN line-of-sight velocity observations combined with an
empirical convection model and the assumption that the resulting
velocity field is divergence free. In contrast to other techniques for
convection estimation, it does not express the velocity field in terms
of known basis vectors and it does not assume that the velocity can be
determined from a static potential. The velocity is estimated by
applying Bayesian inverse theory to the input data, model, and
constraints. Linear equations for the plasma velocity at every point in
the domain are solved simultaneously in a least-squares sense.
Application of the technique results in convection patterns with spatial
resolution equal to the calculation grid. The resulting patterns conform
with expectations based on the observed IMF conditions and display
features that show close correspondence to simultaneously observed
features in the auroral luminosity.