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Recent developments in Dynamic Modelling of the Earth’s Radiation Belts Richard B. Horne, Sarah A. Glauert and Nigel P. Meredith British Antarctic Survey Cambridge, UK Invited talk, ESWW7 Bruges, 16 November 2010

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Importance of Energetic Particles 2003 Hallowe’en magnetic storm –48 satellites reported anomalies –1 total loss Satellite ~ US$ 250 M Launch ~ US$ 100 M Insure ~ 3% /year 300 satellites in Geo orbit alone ~ 1000 satellites in orbit Effects of an extreme event? Baker et al. Nature [2004] 2003 Hallowe’en magnetic storm

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Satellites – Total Loss 2010 Eutelsat W3B28 OctFuel leak, total loss a few hours after launch IS-4 (PAS-4)1 FebOut of service after anomaly, moved to junk orbit Eutelsat W2 27 Jan Out of service after anomaly, moved to junk orbit Sterkh 1 and 2Jan Both satellites failed shortly after launch 2009 Koronas-Foton 2 DecContact lost after power supply problem; total loss Orbcomm 22 FebTotal loss of one satellite expected after power system failure Iridium 33 10 FebDestroyed in accidental collision with defunct Russian milsat Astra 5A16 JanTotal loss after malfunction announced 2008 NiqComSat 1 9 Nov Second solar array fails; total loss DSP 23Mid-Sept Total loss EchoStar 214 JulyPower system failure, total loss NRO-L21FebFailed satellite deliberately destroyed by missile What is the cause – Space Weather ? Other ? Can we help protect satelites?

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Satellites – Serious Interruption to Service 2010 IGS 4B23 AugPower failure, status unknown GOCEJulyGlitch prevents science data transmission (recovered Sept 2010) INSAT 4B7 JulySolar array anomaly; 50% power loss Galaxy 15 5 AprContact lost, transponders still working Aura12 MarAttitude disturbance, slight power loss AMC-16MarFurther degradation of solar arrays, some transponders switched off Satmex V27 JanLoss of XIPS propulsion system, operational life shortened 2009 GeoEye 111 DecProblem with transmit antenna pointing mechanism Landsat 5DecLost transponder replaced by one thought to have failed earlier MTSAT-1R 11 Nov 15.5-hour outage Eurobird 1 12 Sep90-minute outage starting at 2124 UTC attitude problems Chandrayaan 128 AugContact lost; mission abandoned Orbcomm24 AugCoast Guard demo satellite fails Landsat 513 Aug1-day outage Herschel 3 AugSEU causes anomaly in HIFI instrument Sinosat 313 Jul12-hour outage, starting at 1350 UTC Yamal 202 3 June8½-hour outage Eutelsat W2AMayIOT: S-band payload anomaly announced GeoEye1 MayProblems with colour imagery announced Chinasat 6B9 Feb47-minute outage starting 0259; recovered Eutelsat W2M 28 Jan IOT: Major anomaly of power subsystem, likely total loss How important is Space Weather ? Can we help protect satellites?

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Importance of Energetic Particles – Space Weather NOAA anomaly database High flux of MeV electrons cause satellite anomalies (malfunctions) Cumulative radiation dose limits spacecraft lifetime Iucci et al. SW [2005]

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Solar wind – Radiation Belts Increased MeV electron flux in the radiation belts Driven by high speed solar wind and Bz fluctuations Galileo - Giove – A Science and applications Thanks to the ESA Galileo team

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ULF Enhanced Radial Diffusion Fast solar wind drives ULF waves inside magnetosphere ULF wave frequency ~ electron drift frequency ~ mHz diffuse electrons towards/away from the Earth Conservation of 1 st invariant results in electron acceleration/deceleration

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Wave-Particle Interactions As electrons drift around the Earth they encounter many types of waves: Chorus Hiss Lightning generated whistlers VLF transmitters EMIC Magnetosonic Z mode LO and RX modes Wave-particle interactions are mainly responsible for radiation belt variations

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Radial Diffusion and Losses due to Hiss Radial diffusion Wave-particle interactions Whistler mode hiss waves Loss to the atmosphere Underestimates flux Needs electron acceleration Lam et al. GRL [2007]

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Cyclotron Resonant Electron Acceleration: Chorus Whistler mode chorus waves excited by ~1-50 keV electrons Waves accelerate electrons up to MeV energies Horne et al., Nature [2005] Cluster data

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3d Dynamic Global Modelling 3d = Include wave-particle interactions Radial diffusion is for constant J 1 and J 2, - OK on a (J 1,J 2,L*) grid However Momentum diffusion is for constant (L*,y) Pitch angle diffusion (y) is for constant (L*,p) Requires complex differential operators Solution - use 2 grids – and transform between them

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Diffusion Coefficients Radial diffusion coefficients Due to ULF waves Pitch angle and energy diffusion Due to wave-particle interactions Scale coefficients by the Kp index and drive global dynamic model by a time series of Kp

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Salammbo Model [Varotsou et al. 2005, 2008; Horne et al., 2006] Radial diffusion + wpi due to chorus – steady state No cross terms Significant increase in electron flux due to chorus acceleration

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Radiation Belt Environment Model SAMPEX Data 2-6 MeV electrons Radial displacement + chorus No cross terms Fok et al. [2008] Radial diffusion and wpi due to chorus Radial diffusion only Chorus waves are essential for dynamics

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BAS Global Radiation Belt Model Electrons flux - CRRES satellite during a magnetic storm Model without wave-particle interactions - inadequate Model with wave-particle interactions Wave-particle interactions are essential for radiation belt variations and loss to atmosphere

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USAF Model Albert et al. [2009] Includes cross terms 2 grids – coordinates of the second grid are chosen so the cross terms vanish Radial diffusion + chorus give best agreement with data Cross terms reduce chorus acceleration Data Radial diffusion alone Chorus and RD

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Coupling High and Low Energy Electrons

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Coupling low and High Energy Electrons No couplingCouple RCM to VERB code Subbotin et al. JGR [2010]

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BAS code – Effects of Hiss Wave Normal Angle DataBAS Model

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Comparison of Electron Lifetimes Benck et al. [2010] Electron lifetimes (0.23 – 0.34 MeV) are longer when measured at low altitude compared to equator Why?

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Loss timescales SAC – C measures pa ~ 20 O CRRES measures 0-90 Suggest here –Active conditions –Energy diffusion at large p.a. –Energy diffusion at small p.a Important to resolve for global dynamic models

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Conclusions Satellite losses and service interruptions are still significant Radiation belts are variable and pose a hazard Global dynamic radiation belt models are being developed to forecast risk Need for better understanding of the physical processes: Wave-particle interactions – ULF, ELF and VLF frequencies Coupling of radiation belts to the solar wind Transport of low energy electrons – E fields Coupling to major boundaries – such as the plasmapause Galileo provides new opportunities for science as well as applications New SPACECAST project will develop European models and forecasting Wave-particle interactions – radial diffusion

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Reserve Slides

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Needs to improve models Need more wave data for different wave modes – diffusion rates Need better ULF waves data for radial diffusion Couple high and low energy electrons Need better E field model for convection - transport Better coupling from solar wind to magnetosphere – effects of boundaries Develop global models into forecasting models New FP7 SPACECAST project will do some, not all

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Resonance Cone Waves do not propagate at all directions Need to restrict wave power in angle What is the angular spread?? Need observations –CLUSTER Resonance cone Vg k Electrostatic Electromagnetic

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Wave Power Near the Resonance Cone Pitch angle diffusion rate Including wave power near the resonance cone reduces the diffusion rate !! Paradox Reason waves become electrostatic – not electromagnetic Need to revise model Need to identify EM and ES waves in wave data

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Dynamic Modelling Approach Diffusion - complexity in transformations Gyro-kinetic - complexity in wave diffusion Both need very good magnetic field models Observations Transform to a dipole field (L*) Diffusion Calculations Observations Use a realistic magnetic field model Gyro-kinetic Calculations or

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