Dynamics of the polar cap boundary in the evening sector during a substorm event

Pitkänen, T.1, Aikio, A.1, Kozlovsky, A.2 and Amm, O.3

1 Department of Physical Sciences, University of Oulu, Oulu, Finland
2 Sodankylä Geophysical Observatory, Oulu unit, Oulu, Finland
3 Finnish Meteorological Institute, Helsinki, Finland

Plasma flow through the polar cap boundary (PCB) in the ionosphere can be utilized for estimating the reconnection electric field as a measure of the energy transfer from the open magnetic field lines to the closed field line region. In this study, we calculate the ionospheric reconnection electric field in the nightside for a substorm period on November 25 2000. The plasma flow vectors are determined by the dual-beam measurement of the EISCAT VHF radar and the location of the PCB is estimated from the EISCAT measurements on the mainland and on Svalbard. In addition, the convection reversal boundary is determined from the EISCAT data. The PCB is compared with optical satellite measurements by Polar UVI and equivalent east-west electrojets calculated from MIRACLE magnetic measurements by 1D upward continuation.