Hemispheric asymmetry of the vertical ion drifts at dawn observed by DMSP

In the geographic coordinates, the geographic longitudinal variation of V-z is more pronounced in the SH. The seasonal variations of high-latitude V-z are different in the NH and SH. The average asymmetric feature of V-z largely depends on the occurrence and magnitude of ion upflow/outflow, which are modulated by the combined effects of the asymmetric magnetic field configuration between the two hemispheres, and the dynamic processes in the tightly coupled ionosphere-thermosphere system, and their (probably nonlinear) interactions with each other.