Ascienceplanforthestudyof
magnetosphere/ionosphere/
thermospherecouplingwithJuno.
MichelBlanc,NicolasAndré,FranBagenal,Pierre-LouisBlelly,ScoBBolton,
VincentGénot,WilliamKurth,LaurentLamy,PhilippeLouarn,
AurélieMarchaudon,FabriceMoBez,ChristophePeymirat,ChihiroTao,
PhilippeZarka
WarmthankstoEmmaBunce
AuroraPlanningWorkshop,Boulder,CO
March8th,2016
PROBLEMSOFASTROPHYSICALINTEREST
ANGULARMOMENTUMTRANSFER
•  HowisangularmomentumtransferredbetweenacentralmagneYzed
fast-rotaYngobjectanditssurroundingplasmadisk?
LINEARMOMENTUMTRANSFER
•  HowismomentumtransferredbetweenacentralmagneYzedobjectand
asurroundingplasmaflow?
POWERINGARADIOSOURCE
•  Bywhichprocessesdoesthiscouplingbetweenthecentralobjectandits
environmentpowerstrongradioemissionsandturnthecentralobject
intoaradiosource?
M-I-TELECTRODYNAMICCOUPLINGPLAYSAKEYROLE
FielddistorYonandrelatedelectriccurrentsystemassociated
withimperfectrotaYonalcoupling
Bunce&Cowley(2001b),CowleyandBunce,2001
AaerHill(1979)andVasyliunas(1983)
ThemagneYcfielddistorYonisassociatedwithanelectriccurrentsystemwhichhas
à OppositeBφoneithersideofequator
à RadialcurrentintheequatorialplaneassociatedwithjxBforce
à EquatorwardPedersencurrentsintheionosphere
à Upanddowndirectedfield-alignedcurrentswhichjoinandclosethesecurrents
PROPOSEDAPPROACH:
FOCUSON3REGIONSALONGTHISCURRENTLOOP
USINGJUNO
RegionB:
High-alYtudeauroral
fieldlines
RegionC:
Auroral
ionosphereand
thermosphere
RegionA:
plasmasheet/
magnetodisk
(fromCowleyandBunce,2001)
REGIONA:THEMAGNETODISC
•  OBJECTIVE:determinetheradial
currentinthedisk,andtheradial
transportofmassandangular
momentum.
•  MEASUREMENTGOAL:Characterizethe
netradialtransportofmaBer,andthe
magneYctorque,atallscales.
–  Smallscales:interchangeinstability(1)
–  Largescale:globalinstabiliKesofthe
magnetodisk(2)
–  Other?
•  MEANS:
–  SynopYcmulY-instrumentstudies
(fields,waves,parYcles)
–  Modelsoftheprocessesatdifferent
scales
Radialplasmatransport
(1)StudyoftheInterchangeinstabilityatSaturnwithCASSINI
(2) A sketch of the large-scale plasmadisk disruption process
Louarnetal.,JGRblue,119,6,pp.4495-4511(June2014) 7
MagneKcsignatureofangularmomentumtransfertothedisk
onmagnetodiskcrossings
~intersecKonofthemagneto-discneutralplanewiththeeclipKcplane.
Event1
Event2
Event3
Disc
Galileo
Spiral-likepaZernwith
distorsionscorrespondingto
theevents
PWSandMAG-Doy77-93,1997
Louarnetal.,2014
LinkingthediscmagneKctwistandtheradioflux
Exampleofradio/twist
correlaKon
Intense
radioflux=
more
twisteddisc
Obviouslink
withM-I
coupling.
Twist->J_rad
->J//
Hill’smodel:
Wouldbe
connectedto
longterm
variaYonsof
dM/dt
97_84-92
RadioIntensity
PWSandMAG-Doy166-176,
1997
97_168-17
2
97_253-25
8
Twist-Model(twist)
Louarnetal.,2016
REGIONB:AURORALFIELDLINES
OBJECTIVES:
•  Characterizetheauroral
acceleraYonregionsatall
scales,andthenetfieldalignedcurrentflow
•  Integrateacrossallscales
tofindtheeffecYve
current-voltage
characterisYcs
•  IdenYfythesourcesof
freeenergywhichpower
radioemissions
MEANS:
•  SynopYcmulY-instrument
studies
•  Detailedstudyoftheexact
conjugacybetween
acceleraYonregionsand
auroralforms
CHARACTERIZINGAURORALFIELDLINES
EXAMPLEOFEARTHCAVITIES
Densitycavity
Electricfield
JparfromDeltaB
IonacceleraKon
ElectronacceleraKon
Atopsideionosphericcavityobservedby FAST(Chastonetal.,2006)onEarthorbit
REGIONC:AURORALIONOSPHERE
ANDTHERMOSPHERE
TWOCOMPLEMENTARYTOOLS
2-DMAPPINGOFKEY
QUANTITIES:
•  Field-alignedcurrents
•  ParYcleprecipitaYonfluxes
•  AssociatedenergydeposiYon
3-DMODELING:
•  Ionospheremodel(IPIM)
•  M-I-Tcouplingmodel(TIEGCM)
•  Providingsuchoutputsas:
IonosphericconducYviYes,winds,Joule
heaYngandangularmomentumbudgetof
thermosphere
3-DIPIM-JupiterIonospheremodel
(BlellyandMarchaudon)
ATMOSPHERE
MSIS Model
N N - TN
HWM Model
VN - WN
H - N - O - N 2 - O2
INDICES
a p F10.7
hν
MAGNETOSPHERE
ur ur
E⊥, J P
Electrodynamics
ur
B
O
h
ν
eV
O
H
O+
FLUID MODEL
H
H+
O
2
N2
NO
e
O
e
NO
O2
16 - moment
transport equation
N+
O2
dissociative ionization
O
+
NO
N
NO
2
NO
N - TP - T⊥ - V - QP - Q⊥
+
H - N + - O + - NO + - N 2 + - O 2 +
N
O2
thermal e-
ν
eV
eV
O2
+
2
h
h
O
ν
O2
Te , N e
ur
B
KINETIC MODEL
transport equation
suprathermal e -
N
O
+
2
Magnetic
Geometry
F, E
N2
Pi , Θe
ion production rate
electron heating rate
excitation rate
2-DM-I-Tcouplingmodel
(C.Tao)
⇒calculate(i)thermosphere/Ionospheremodeland(ii)torque
equaYonoftheout-flowingmagnetosphericplasma,interacYvely
Neutralwind
(i)Thermosphere/Ionosphere2D
Field-alignedcurrent
(3componentsinlaYtude&alYtude)
(FAC)
(ii)Magnetosphericplasma1D
(azimuthalcomponentinradial)
Magnetospheric
Jupiter
plasma
AssumpYon:
Fig.ModelRegion
・RotaYonaxisymmetric
・IgnoringtheAlfventransitYme
StaYccondiYon
・MagneYcfield
dipoleonionosphere
empiricalmodelatmagnetosphericequator[NicholsandCowley,2004]
Results
CouplingCurrent&Thermosphere
Ionosphere→
Magnetosphere
(auroral ele. prec.)
meridional temperature & wind
max(Vy)=77 m/s
max(Vz)=0.98 m/s
Magnetosphere
→Ionosphere
Fig. Latitudinal distribution of FAC (left) and meridional temperature and wind fields (right).
FAC is formed
⇔Obs. 0.04-0.4 µA/m2
[Gustin et al., 2004]
Temperature: Joule heating in high latitudes
Meridional circulation : heating in the high latitudes
Energy budget: where does Jupiter rotational
energy go? Magnetodisk rotation, atmosphere
heating?
Howtofeedthemodelwith
JunoobservaYons?
Step-1:Relatemodelparameterswithobservableparameters
Field-alignedcurrent⇔ UV+MAG
IonosphereH3+density+temperature⇔ IR
Step-2:ConstrainparametersbyobservaYonandcomparison
magneYcfield+UVàfield-alignedcurrent
parYcleobs.àauroralelectronspectrum,mag.plasmavelocity(?)
IRobs.àtemperature
IRhigh-spectralobs.(ground-based)àwindfield
*Linktheseobservedparameters
Field-alignedcurrent inamodeltoevaluateenergy
Magnetospheric transferinthesystem
*Constrainhowmuch
plasma
“addiYonal”heaYngisrequired.
Neutralwind
Jupiter
Fig.ModelRegion
Orotherideas/suggesYons?
3-DM-I-TCOUPLINGMODELFORJUPITER
(C.Peymirat,workinprogress)
è NondipolemagneYcfleidmodel èSourcesoftheplasma è Transportofmagnetosphericplasma
èField-alignedcurrents ==>EulerpotenYals
==>ringsandsatellites
==>centrifugalforce,corotaYonelectricfields,
ionosphericdynamo
==>generatedbysatelliteandtorimoYons
FIELD-ALIGNED
CURRENTS
J//
PLASMA
IONOSPHERIC
TRANSPORT
NEUTRALWINDS
DYNAMO
Vn
E
MAGNETOSPHERE
ELECTRIC
ELECTRIC
FIELD
FIELD
E
E
IONOSPHERE
THERMOSPHERE
CONCLUSIONS
•  Understandingmomentumtransferthroughthe
diversityofmagnetospheresisaproblemofmajor
astrophysicalinterest
•  Junooffersauniqueopportunitytostudyitinthe
referencefastrotaYngmagnetosphere.
•  AddressingthismajorscienceobjecYverequires:
•
•
•
•
Afocusonthethree«keyregions»
appropriatelyplannedobservaYons,
efficienttoolsformulY-instrumentstudies,
modellingtools
•
ALLINTERESTEDCOILLEAGUESANDTEAMSARE
INVITEDTOJOINTHISTEAMEFFORT
ThankyouverymuchforyouraZenKon!
ThistalkparYallyreflectstheoutcomeofaseminar
organizedbyIRAPandLESIAinToulouseonoct.13and14,2015.
Allpresentatlonsareavailableat:
hBp://cdpp.eu/workshops/Jupiter_MIT_coupling/
Pioneering work by the Leicester group, following Tom Hill’s initial works, visited via
an analytic approach the diversity of coupling currents and plasma flows :
IonosphericFlowsandCurrents
TakenfromCowley[2001]
TakenfromCowleyetal[2003]
TakenfromCowleyetal[2004]
The field-aligned currents that flow between the ionosphere/thermosphere and
magnetosphere in planetary plasma systems are fundamental to the processes that
transfer stress between these regions via the planetary magneYc field (see, e.g., the
reviewbyCowley[2000]).