A Statistical Study of Ion Upflow during Periods of Dawnside Auroral Polarization Streams and Subauroral Polarization Streams

We have investigated the effect of dawnside subauroral polarization stream (SAPS) and auroral (DAPS) on ionospheric ion upflow in Northern Hemisphere by using four years Defense Meteorological Satellite Program (DMSP) observations. The occurrence rate DAPS is higher than that SAPS. Obvious occurs topside ionosphere around region. SAPS vertical flow weakened when geomagnetic activity increases. There are prominent fluxes DAPS, while there insignificant plasma density trough during periods becomes shallower with increasing magnetic activity. These variations might be due to ion-neutral collision heating efficiency highly disturbed periods. no obvious or temperature drop region at altitude ~800 km. area decreases, electron increases regions.