2011 SuperDARN Workshop
Testing the Equipotential Magnetic Field Line Assumption Using Interhemispheric SuperDARN Measurements
J.B.H. Baker (1), B.S.R. Kunduri (1), L.B.N. Clausen (1), J.M. Ruohoniemi (1), A. Grocott (2), M. Freeman (3)
(1) Bradley Department of Electrical and Computer Engineering, Virginia Tech., Blacksburg, VA 24061, USA.
(2) Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, U.K.
(3) British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, U.K.
abstract. An important assumption often made in space physics is that magnetic field lines can be treated as electrostatic equipotentials. This assumption tells us that electrodynamic processes occurring at both ionospheric ends of a closed magnetic field line should be very similar, even when there might be substantial interhemispheric differences in ionosphere-thermosphere conditions (e.g. seasonal effects). The net result is to produce a common electrostatic potential structure for the entire magnetic flux tube that includes averaged effects of electrodynamic influences at both ends. In this presentation we examine the validity of the equipotential magnetic field line assumption using SuperDARN radars in both hemispheres. We examine event intervals in which north-south pairs of SuperDARN radars with nominally conjugate fields of view observed simultaneous measurements of ionospheric convection. We use empirical magnetic field models to map the radar measurements between the hemispheres to rigorously examine the consistency between the flows. A particular emphasis is placed on examining the conjugacy of subauroral features observed simultaneously by the mid-latitude Wallops and Blackstone radars in the northern hemisphere and the Falkland Islands radar in the southern hemisphere.