Statistical Analysis Of The Field Current In The Polar Region

Field-aligned currents play an important role in the delivery of momentum and energy between the ionosphere and magnetosphere.The activities of auroral are in good relationship with FAC which can be detected the inner link of different process by the change of FAC and its response to other factors.Thus researching FAC is the foundamental course of geospace environment.In this paper,by analyzing the spatial and temporal distribution of FAC detected by CHAMP and Swarm satellites under different IMF components and seasons,we can study the reasons of different distribution focus on the source region of FAC and different physical process.Meanwhile it is the first time we directly compare the different spatial and temporal distribution of FAC between north and south hemisphere and exploring the possible reason of that.Furthermore,we compare the statistic analysis of CHAMP and Swarm on statistical approach and computing method as well as the cause of discrepancy.Finally we explored the relationship between FAC and auroral electron participation flux given by OVATION model.The main result of paper are summarized as followed:1.The spatial and temporal disrtribution of FAC is mainly changed it's equtoward and polarward boundary as well as the mean value under the influence of IMF Bz component,when Bz is negative,the boundary move toward the two sides;While the By component mainly affect the FAC distribution on the flow direction of duskside R1 current,when By is positive upward current domain,the result reversed when By is nagetive.2.The different distribution of FAC between south and norrh semisphere mainly manifested in the flow direction of R0 and R1 current.And the responses of FAC magnitude and distribution to IMF component and season are different,which may be caused by the source region of R0 current and the influence of dip of earth magnetic field.3.The diecrepancy of statistic analysis between CHAMP and Swarm satellite is affected by the combination of statistical approach and computing method.Swarm satellite provide the more accurate and more stable value of FAC.Moreover Swarm can detect the more detailed resolution ratio and the response time to IMF component is short within one hour.4.The main area of monoenergetic electron participation flux is correlated with the duskside upward R1 current.By statistical linear fitting in 1500-2200 MLT,we find out the dependency of FAC on the monoenergetic electron auroral is really high.