| Magnetic storm is an important phenomenon of space weather.Oxygen ion Originated in the ionospheric is an important part of the ring current,and ring current process play an important role in dynamics of magnetic storm(Lotko et al.,2007).The methods of magnetosphere ring current research mainly include satellite field measurements and ENA imaging technology.In article,we use ENA imaging data of two TWINS satellite to analysis the related characteristics of ring current during magnetic storm.In order to be able to distinguish ENA composition,the initial pulse height statistical fitting method is applied to separation of hydrogen and oxygen atoms from ENA,then we can obtain ENA-H and ENA-O differential flux distributions with the lines-of-sight(LOS).We investigated the ring current characteristics during two main magnetic storm events,which is respectively July 15,2012 and June 28,2013.The following results:1.Compare ENA-H and ENA-O differential flux distributions with the lines-of-sight during the great main phase(16:45-17:00)on July 15,2012,we found the obvious enhancement rays of ENA-H concentrate in certain areas,but these of ENA-O distribute in a relatively scattered area;ENA-H displays intense Low Altitude Emissions(LAEs),but ENA-O does not appear obviously LAE.By investigating the ENA enhanced rays through the division of space grid,we find that there are certain MLT differences between ENA-H and ENA-O,and ENA-O ray concentrate after dusk,when the ENA-H focus at dusk and after midnight.2.Survey ENA-H and ENA-O development at 5 rapid growth times at the main phase during magnetic storm(July 15,2012)from TWINS-S1 satellite.Find that,with the growth of the magnetic storm main phase,the average flux of ENA-H is reducing,and ENA-O average flux is increasing.Ratio(ENA-O average flux/ENA-H average flux)and Dst index has consistent over time.These characteristics are similar with O+ and H+ energy density changing with Dst which is analysed by satellite field measurement during a great main storm.3.Investigation of the ring current H+ and O+ ion flux distribution inversed by ENA data at the main phase(16:45-17:00)during a great magnetic storm on July 15,2012,we find that it is similar for H+ and O+ that strong ion flux distribution is in the evening and midnight side.The enhancement areas of H+can spread to larger L value area in midnight side,But the enhancement areas of O+ flux mainly remain in the 3-5 L region.Only for the 16 kev,O+ ion flux increases obviously at dawn side.There are different trends between O+and H+ at the ion energy flux variety with energy level.4.During the main phase in storm on July 15,2012,O+/H+ proportion of ring current equatorial plane develops with MLT similarly between 16 keV and 32 keV,and proportion variety presents the bimodal structure,which is for great proportion in the dusk and dawn.5.For the ring current ion flux inversed by ENA data during three times in the magnetic storm on June 28,2013,Mlt of enhancement areas are mainly in the dusk and midnight area for H+ and O+.At the main phase greatly,Mlt of the enhanced ion flux areas cover widely,from dusk to midnight,even dawn.For the L value,O+ enhanced flux is between 3-5,But enhanced H+ flux can spread significantly to more than 7 in the recovery phase.Overall,space area of O+ enhanced flux is smaller than H+. |
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