Central polar cap convection response to short duration southward Interplanetary Magnetic Field

P. T. Jayachandran (1) , J. W. Macdougall (1)

1 Department of Electrical Engineering

Central polar cap convection changes associated with southward turnings of the Interplanetary Magnetic Field (IMF) are studied using a chain of Canadian Advanced Digital Ionosondes (CADI) in the northern polar cap. A study of 32 short duration (~1 h) southward IMF transition events found a three stage response: (1) initial response to a southward transition is near simultaneous for the entire polar cap; (2) the peak of the convection speed (attributed to the maximum merging electric field) propagates poleward from the ionospheric footprint of the merging region; and (3) if the change in IMF is rapid enough, then a step in convection appears to start at the cusp and then propagates antisunward over the polar cap with the velocity of the maximum convection. On the nightside, a substorm onset is observed at about the time when the step increase in convection (associated with the rapid transition of IMF) arrives at the polar cap boundary.

Domaines: Océan, Atmosphère; Sciences de la Terre

P. T. Jayachandran, J. W. Macdougall. Central polar cap convection response to short duration southward Interplanetary Magnetic Field. Annales Geophysicae, 2000, 18 (8), pp.887-896. ⟨hal-00316729⟩