| In this paper,we use multi-satellite and multi-geomagnetic station joint observations to analyze the triggering characteristics of main phase substorms,and linearly analyze the correlation between magnetic storms and solar extreme ultraviolet radiation?EUV?during the 23rd and 24th solar cycle.We divided the dissertation into two parts:In the first part,observation data from multi-satellites and multi-geomagnetic stations are jointed to investigate the features of the intense substorms (AEmax?3708 n T)during the main phase of the strong storm on 24 August,2005((SYM-Hmin?-179 n T) and the intense substorms(AEmax> 1000 n T)during the main phase of the moderate storm on 27 August,2014((SYM-Hmin?-179 n T)?-90 n T).For the main phase substorm on 24 August,2005,the observation data from OMNI,TC-2,LAN L1994-084,LANL-97A,C luster and eight mid and high magnetic latitude geomagnetic stations were used to investigate.The timing of the features of this main phase substorm was inside-out:firstly,at?09:40:10 UT,in the post-midnight?00:52:30MLT?,TC-2 observed magnetic dipolarization inside geosynchronous orbit(?-6.0,-1.40,-0.89?).Secondly,around 09:41:20 UT,geomagnetic stations PGEO?295.88°/59.18°?and WHIT?277.73°/63.92°?observed Pi 2 geomagnetic pulsation.Thirdly,at?09:43:20 UT,in the post-midnight?01:11:48 MLT?,in the mid-tail??-17.75,-5.75,-0.59?RE?,C luster-1 observed fast tailward ion flow and the BZ component of magnetic field turned to the anti-direction subsequently,which means magnetic field the magnetic reconnection occurs.Finally,at?09:44:30 UT,geostationary satellite LANL1994-084??-6.11,2.42,0.78?RE?observed proton dispersionless injection in the pre-midnight?22:33:34 MLT?.We infer that the onset position of this substorm is located at the dusk-side of TC-2 inside geosynchronous orbit and the main phase substorm is likely to be triggered by some instability.Secondly,Observation data from OMNI,THEMIS-D?TH-D?,THEMIS-E?TH-E?and two THEMIS ground stations are used to investigate the main phase substorm on27 August,2014.In the light of the feature that the magnetic dipolarization expanded from inside?TH-D?to outside?TH-E?geosynchronous orbit,we infer that this main phase substorm also conformed to the"inside-out"substorm model,which was possibly triggered by ballooning instability in the near-Earth plasma sheet.Two magnetic dipolarizations observed by TH-D inside geosynchronous orbit with tailward ion flows and the increase of the energetic electron energy flux indicate that the inner magnetosphere has a new energy transfer path during the main phase substorm.In the second part,the statistics of 361 magnetic storms with moderate and flux before the storm minimum value Dstmin ,F10.7pre),during the 23rd and 24th solar cycle are presented.We used F10.7 index to represent the solar extreme ultraviolet radiation?EUV?intensity and the solar activity level.The correlation between Dstmin and F10.7preis investigated by linear analysis.The statistical analysis results show that during the 23rd and 24th solar cycle:firstly,t he solar activity level in 23rd solar cycle is significantly higher than that in the 24th solar cycle.The number and intensity of magnetic storms are affected not only by the different phase of the solar cycle but also by the solar activity level possibly.Secondly,the probability of strong(-200 n T?Dstmin?-100 n T)and big(Dstmin-200n T)storms occurrence rate increases with increase in the solar extreme ultraviolet radiation?F10.7?during 23rd solar cycle.Thirdly,there is moderate positive that the big storms mainly occur under high solar extreme ultraviolet radiation conditions?F10.7>1501?).We infer that the solar EUV plays an important role in the ionosphere-magnetosphere coupling during big storms.Our results that there exists the moderate positive correlation between big storms and solar extreme ultraviolet radiation can provide foundation information for space weather forecasting. |
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