Hemispheric asymmetry of subauroral ion drifts: Statistical results

摘要: A large database of more than 18,000 subauroral ion drift (SAID) events from DMSP observations 1987 to 2012 is used systematically investigate the features SAID. SAID occurs mostly at ~62°/−60° magnetic latitude (MLAT) and ~22:15/22:45 local time (MLT) for geomagnetically quiet conditions ~58°/−56° MLAT MLT disturbed in North Hemisphere (NH)/South (SH), respectively. Significant north-south asymmetries occurrence, shape, geomagnetic activity variations are found this statistical study. The latitudinal width a larger NH SH. An interesting finding work that occurrence probability peaks have an ~180° difference longitude between two hemispheres geographic coordinates both conditions. almost same meridian zone with ~80°–120° hemispheres. hemispheric spike signatures sharp dips all profiles horizontal velocities SAIDs. highly correlated activity, indicating location evolution might be influenced by global auroral dynamics, dynamics ring currents.