简介：Magneticreconnectionisthemostfundamentalenergy-transfermechanismintheuniversethatconvertsmagneticenergyintoheatandkineticenergyofchargedparticles.Forreconnectiontooccur,thefrozen-inconditionmustbreakdowninalocalizedregion,commonlycalledthe‘diffusionregion’.InEarth’smagnetosphere,iondiffusionregionshavealreadybeenobserved,whileelectrondiffusionregionshavenotbeendetectedduetotheirsmallscales(oftheorderofafewkm)(Paschmann,2008).Inthispaperwereport,forthefirsttime,insituobservationsofanactiveelectrondiffusionregionbythefourClusterspacecraftattheEarth’shighlatitudemagnetopause.Theelectrondiffusionregionischaracterizedbynongyrotropicelectrondistribution,strongfield-alignedcurrentscarriedbyelectronsandbi-directionalsuper-Alfvénicelectronjets.Alsoobservedweremultiplemicro-scalefluxropes,withascalesizeofabout5c/ωpe(12km,withc/ωpetheelectroninertiallength),thatarecrucialforelectronaccelerationintheguide-fieldreconnectionprocess(Drakeetal.,2006a).Thedatademonstratetheexistenceoftheelectrondiffusionregionincollisionlessguide-fieldreconnectionatthemagnetopause.

简介：PlatesubductiondrivesboththeinternalconvectionandthesurfacegeologyofthesolidEarth.Despitetherapidincreaseofcomputationalpower,itremainschallengingforgeodynamicmodelstoreproducethehistoryofEarth-likesubductionandassociatedmantleflow.Here,basedonanadaptiveapproachofsequentialdataassimilation,wepresentahigh-resolutionglobalmodelsincethemid-Mesozoic.ThismodelincorporatesthethermalstructureandsurfacekinematicsoftectonicplatesbasedonarecentplatereconstructiontoreproducetheobservedsubductionconfigurationandEarth-likeconvection.Introductionoftemperature-andcomposition-dependentrheologyallowsforincorporationofmanynaturalcomplexities,suchasinitiationofsubductionzones,reversalofsubductionpolarity,anddetailedplate-boundarydynamics.Theresultantpresent-dayslabgeometrywellmatchesBenioffzonesandseismictomographyatdepths<1500km,makingitpossibletohindcastpastsubductiondynamicsandmantleflow.Forexample,themodelproducesaflatFarallonslabbeneathNorthAmericaduringtheLateCretaceoustoEarlyCenozoic,afeaturethathasbeengeodynamicallychallengingtoreproduce.Thishigh-resolutionmodelcanalsocapturedetailsofthe4-Devolutionofslabsandtheambientmantle,suchastemporallyandspatiallyvaryingmantleflowassociatedwithevolvingslabgeometryandbuoyancyflux,aswellastheformationofshallowslabtearsduetosubductionofyoungseafloorsandtheresultingcomplexmantledeformation.Suchageodynamicframeworkservestofurtherconstrainuncertainplatereconstructioninthegeologicalpast,andtobetterunderstandtheoriginofenigmaticmantleseismicfeatures.

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