High‐latitude ionospheric convection during strong interplanetary magnetic field By

Abstract

An unusual high‐latitude ionospheric convection pattern was observed on March 23, 1995. The dayside ionospheric convection appeared as a clockwise merging convection cell focused at 84° magnetic latitude around 1200 MLT. No signature of the viscous convection cell in the afternoon sector was observed. The interplanetary magnetic field (IMF) conditions corresponding to the occurrence of the ionospheric convection were Bx ≈ 1 nT, By ≈ 10 nT, and Bz<0 (|Bz| ≪ By). We have compared our observations with statistical patterns and MHD numerical models for similar IMF conditions. It is found that the location of the convection cell focus in this event is at least two hours earlier than those previously observed and about 5 hours earlier than that predicted by the MHD model. The observations may have some significant implications on the antiparallel merging theory.