A Statistical Analysis On The Responses Of The Upward Ions In Polar Ionosphere On The Geomagnetic Activities And Seasonal Changes

There are many kinds of ions bulk outflow and energization processes in the polar ionosphere, which make ionosphere be the main source of the magnetospheric plasma. The transportation of plasma from ionosphere to magnetosphere is called as ion upward, which is one of the important ways in the ionosphere-magnetosphere coupling processes.The plasma upward events occurred in different positions have different morphological characteristics and associated with the different acceleration mechanism, using statistical methods to analyze spatial and temporal distribution and variation of the upward events could help us better understanding of the upward process. Based on a large dataset of ion drift velocity measurements boarding on DMSP F13satellite and interplanetary magnetic field measurements boarding on Wind satellite, a study is made on the plasma upward in the topside polar ionosphere, the emphasis is put on the quit-time and the storm-time changes in distribution of upward occurrence and the impact of different interplanetary magnetic field and magnetic local time and seasons on the upward occurrence. The research obtained results as follows:(1) In the northern hemisphere, the upward events mainly occur from magnetic local time six to nineteen, while in the southern hemisphere, the upward events mainly occur from seventeen to nineteen, and both the speed of the upward events are mainly concentrated between two hundred meter per second and five hundred meter per second;(2) When in the southern hemisphere and northward interplanetary magnetic field, the occurrence possibility of upward events is bigger than that in the southern hemisphere and southward interplanetary magnetic field, when in the northern hemisphere and southward interplanetary magnetic field, the occurrence possibility of upward events is bigger than that in the northern hemisphere and northward interplanetary magnetic field, and this conclusion in the magnetic storm period is more obvious than the quiet period.(3) In southern hemisphere, the occurrence possibility of upward events in winter is more than that in summer, and in northern hemisphere the occurrence possibility of upward events in summer is more than that in winter, and for the upward events happened in summer of the southern hemisphere southward interplanetary magnetic field and the north hemisphere northward interplanetary magnetic field, season plays a greater role than storm.In all, the flux, flux density, rate, occurrence possibility and the distribution of the upward ions are constantly changing. However, the geomagnetic activities and solar activities are the major factor which affecting these changes.