GLOBAL PERSPECTIVE OF IONOSPHERIC TRAVELING CONVECTION VORTICES - CASE-STUDIES OF 2 GEOSPACE ENVIRONMENTAL MODELING EVENTS

Two very different events of high-latitude ionospheric traveling conve ction vortices (TCV) are studied on the basis of a very broad and dens e collection of ground-based magnetometer data. A new display techniqu e is introduced and used for the analyses. Many of the previously repo rted features of these events are confirmed, but some new features are revealed. Both events exhibit pronounced postnoon/prenoon asymmetry. Much substructure and complex dynamics of the vortex structures are al so evident. One of the events is observed to be closely related to a v ery sudden and strong change in the large-scale polar ionospheric conv ection system. The difference between the two events, not only in this point, indicates the existence of at least two classes of TCV events, the distinction of which requires global analysis.