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Carlson et al. ‘01 Three Characteristic Acceleration Regions
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Carlson et al. ‘01 Alfvén Wave Induced Outflow
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OUTFLOW Strangeway et al. ’02 Ponderomotive Lifting via Alfvén Waves a p|| = ¼ || (E /B 0 ) 2 > GM E /r 2 for E > 200 mV/m at 1000 km altitude
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Li and Temerin ‘93 Ponderomotive Force (in a cold magnetized plasma)
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Electrodynamic Coupling: Energy Dissipation ̶ Joule heating ̶ Current-Voltage relation ( Knight; ?) ̶ Alfvén wave induced dissipation (?) Inertial Coupling: Mass Exchange ̶ Bulk outflows – polar wind ̶ Fractional outflows – energization (O + )
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MIC LFM RCM LFM RCM LFM RCM TING MIC TING MIC seconds iterate minutes 1½-way LFM-RCM coupling w/ convergent, iterative, 2-way TING coupling LFM TING Empirical SWM Precip W ||, E 0 j || s m B RCM s TING M-I Coupler
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minutes LFM TING SWM B 2 > j || s m B RCM s M-I Mass Coupler minutes Gravity = Ponderomotive Force at 1000-km altitude for n O+ = 10 10 /m 3 and B = 80 nT MIC LFM RCM LFM RCM TING
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|| = j || / K K = (n eff /n ps ) K Knight Banks and Holzer ‘69 Lemaire and Scherer ‘73 Field-Aligned Potential Drop Effects of Loss Cone n eff /n ps = 1 – (1 – B ps /B) ½ Bohm Criterion v ||i = c s into || Neutral Gas Temperature in T n Density Scale Height v ||e B/n eff
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Keiling et al. ‘03 VisibleFUV Downward Poynting Flux Upward Poynting Flux Auroral Morphology as seen in
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Carlson et al. ‘01 Alfvénic Acceleration Regions
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Intense, field-aligned Poynting fluxes flow earthward along the “lobe-plasma sheet” interface Polar FAST MPA UVI Lobe Plasma Sheet Polar Cap Auroral Zone Wygant et al. ’00
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CISM All Hands Meeting 15 Sep 2003 LFM Low-Altitude Boundary TING High-Altitude Boundary
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LFM Low-Altitude Boundary TING High-Altitude Boundary
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“Quasi-static” Alfvén waves Alfvén-wave Lorentz Force
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Banks and Holzer ‘69
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Questions LFM BCs on , T? Inner boundary at r = constant where r b 0 r v E 0, i.e., v E has a component normal to the boundary. TING Ion energy and momentum equations? Same ion composition in E and F layers?
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Grid Specification MM RCM TIM MIC CHART LEGEND Source of Numerical Data Magnetospheric Model Ring-Current Model Thermosphere-Ionosphere Model M-I Coupler “Variable A from MM on the MM grid and variable A from RCM on the RCM grid are interpolated onto the MIC grid” MIC RCMMM A
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seconds minutes MIC MM RCM MM RCM MM RCM MIC 1½-way LFM-RCM coupling MM Empirical SWM Precip W ||, E 0 j || s B RCM s M-I Coupler
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iterate minutes MM RCM MM RCM TIM MIC TIM MIC Convergent, iterative, 1-way TING coupling MM TIM Empirical SWM Precip W ||, E 0 j || s m B RCM s M-I Coupler
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Auroral Electrodynamics Opgenoorth et al. ‘02
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Ionospheric Feedback Atkinson ’70; Sato ‘78 Polarization Field-Aligned Current
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Two-fluid MHD model of the magnetosphere Electron parallel momentum equation Electron parallel momentum equation Density continuity equation Density continuity equation Current continuity equation Current continuity equation where v ||e - electron parallel speed; IC - electron collision frequency; AR - effective collision frequency representing the effects of plasma anomalous resistivity. where ρ i - ion Larmour radius.
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Model of the auroral ionosphere Density Continuity Equation where n = n 0 + n 1 - plasma number density; - ionization source maintaining equilibrium density n 0 outside the region of auroral precipitations; j || - field-aligned current; - recombination coefficient. Current Continuity Equation where P and H are height-integrated ionospheric Pedersen and Hall conductances.
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“Feedback” Unstable Alfvén Waves Growth rate vs P, E and k Two resonant cavities Large-Scale Resonator Small-Scale Resonator Pokhotelov ‘02
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Feedback Instability Ionospheric Alfvén Resonator E Layer J J N e +– N e 2 +– P +– E – + Stable? yesno Streltsov and Lotko ‘02 125 s 297 s 281 s 266 s 251 s 235 s 220 s 204 s 188 s 173 s 157 s 141 s E NS 670 mV/m equator ionosphere L = 7.258.25
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Streltsov and Lotko ‘02 600 400 0 200 mV/m E NS B EW 050100150200 nT distance, km 0 50 100 150 (mV/m) 2 km 00.050.250.200.150.10 k , km -1 (nT) 2 km 0 -50 -100 -150 -200 0 4 3 2 1 5 PEPE PBPB Time Step = 297 s E NS B EW j 670 mV/m 270 nT 80 A/m 2 ionosphere equator “Satellite” Measurements
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E NS (mV/m) L = 8.25 7.25 IONOSPHERE 1 R E 44 R E Animation sequence from 0 < t < 300 s
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