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1、JOURNALOFGEOPHYSICALRESEARCH,VOL.116,A09218,doi:10.1029/2011JA016489,2011Statisticalsurveyonthemagneticstructureinmagnetotailcurrentsheets1,212345Z.J.Rong,W.X.Wan,C.Shen,X.Li,M.W.Dunlop,A.A.Petrukovich,6,78T.L.Zhang,andE.LucekReceived21January2011;revis
2、ed18May2011;accepted21June2011;published21September2011.[1]OnthebasisofthemultipointmagneticobservationsofClusterintheregion15–19REdowntail,themagneticfieldstructureinmagnetotailcurrentsheet(CS)centerisstatisticallysurveyed.ItisfoundthattheBycomponent(i
3、nGSMcoordinates)isdistributedmainlywithin∣By∣<5nT,whiletheBzcomponentismostlypositiveanddistributesmainlywithin1∼10nT.Theplaneofthemagneticfieldlines(MFLs)ismostlyverticaltotheequatorialplane,withtheradiusofcurvature(Rc)oftheMFLsbeingdirectedearthwardan
4、dthebinormal(perpendiculartothecurvatureandmagneticfielddirection)beingdirectedazimuthallywestward.ThecurvatureradiusofMFLsreachesaminimum,Rc,min,attheCScenterandislargerthanthecorrespondinglocalhalfthicknessoftheneutralsheet,h.Statistically,itisfoundth
5、attheoverallsurfaceoftheCS,withthenormalpointingbasicallyalongthesouth‐northdirection,canbeapproximatedtobeaplaneparalleltoequatorialplane,althoughthelocalCSmaybeflappingandisfrequentlytiltedtotheequatorialplane.ThetiltedCS(normalinclinedtotheequatorial
6、plane)isapttobeobservednearbothflanksandismainlyassociatedwiththeslippageofmagneticfluxtubes.Itisstatisticallyverifiedthattheminimumcurvatureradius,Rc,min,halfthicknessofneutralsheet,h,andtheslippingangleofMFLs,d,intheCSsatisfiesh=Rc,mincosd.The2current
7、density,withameanstrengthof4–8nA/m,basicallyflowsazimuthallyandtangentiallytothesurfaceoftheCS,fromdawnsidetotheduskside.Thereisanobviousdawn‐duskasymmetryofCS,however.Formagneticlocaltimes(MLT)∼21:00–∼01:00,theCSisrelativelythinner;theminimumcurvaturer
8、adiusofMFLs,Rc,min(0.6–1RE)andthehalf‐thicknessofneutralsheet,h(0.2–0.4RE),arerelativelysmaller,andBz(3–5nT)andtheminimummagneticfield,Bmin(5–7nT),areweaker.ItisalsofoundthatnegativeBzhasahigherprobabilityofoccurrenceandthecross‐
