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Carlson et al. ‘01 Three Characteristic Acceleration Regions Carlson et al. ‘01 Alfvén Wave Induced Outflow OUTFLOW Ponderomotive Lifting via Alfvén Waves ap|| = ¼||(E/B0)2 > GME/r2 for E > 200 mV/m Strangeway et al. ’02 at 1000 km altitude Ponderomotive Force (in a cold magnetized plasma) mi E2^ e2 1 1 2 2 F = Ñ E E » Ñ pi 4mi w2 - w2 ^ w2 4 B2 ci 0 E E^ w wci 1 Li and Temerin ‘93 • 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+) SWM LFM LFM B s RCM minutes LFM Precip W|| , E0 TING LFM RCM RCM RCM j|| s LFM MIC seconds MIC Φ TING RCM MIC Empirical Σ M-I Coupler ΣΦ vn × B j || MIC minutes TING Σ ,vn MIC iterate Φ TING TING m 1½-way LFM-RCM coupling w/ convergent, iterative, 2-way TING coupling SWM LFM LFM S E B bˆ B s minutes RCM LFM B2> LFM RCM RCM RCM j|| s TING minutes MIC j B M-I Mass Coupler V O+ V n bˆ g O n + bˆ O O n + P O + Pe B2 / 20 + Gravity = Ponderomotive Force at 1000-km altitude for TING TING m nO+ = 1010/m3 and B = 80 nT Auroral Morphology as seen in Visible FUV Upward Poynting Flux Downward Poynting Flux Keiling et al. ‘03 Carlson et al. ‘01 Alfvénic Acceleration Regions Polar Lobe Intense, field-aligned Poynting fluxes flow earthward along the “lobe-plasma sheet” interface Polar Cap Plasma Sheet FAST UVI MPA Auroral Zone Wygant et al. ’00 S (, L,t ) E H LFM Low-Altitude Boundary TING High-Altitude Boundary CISM All Hands Meeting 15 Sep 2003 S (, L,t, ) E B 0 LFM Low-Altitude Boundary B , j E ,V O+ TING High-Altitude Boundary V O+ 1 1 2 ˆ b g P P B e / 2 0 O+ O+ n O+ V n E ,u TING High-Altitude Boundary d i dt du i i B dt dPi dt 5 3 1 i ui d S+L dt B Pi B t ( u E bˆ u i ) P P B /2 g bˆ rˆ u 2 e i i in 0 in i u n mn 2 2 k (Tn Ti ) (ui u n ) Qi B mi mn 3 ui Alfvén-wave Lorentz Force eni v B eni v Pol B J Pol B B2 2 0 “Quasi-static” Alfvén waves r0 h B C1 ( , L) B B 0 ( , L) r 3/2 r0 hL BL C 2 ( , L) BL BL 0 ( , L) r 3/2 Banks and Holzer ‘69 Questions LFM • BCs on , T? • Inner boundary at r = constant where r b 0 r vE 0, i.e., vE has a component normal to the boundary. TING • Ion energy and momentum equations? • Same ion composition in E and F layers? CHART LEGEND Grid Specification Source of Numerical Data Magnetospheric Model MM Ring-Current Model RCM TIM Thermosphere-Ionosphere Model MIC M-I Coupler MM RCM A MIC “Variable A from MM on the MM grid and variable A from RCM on the RCM grid are interpolated onto the MIC grid” SWM MM MM B s minutes RCM MM Precip W|| , E0 MM RCM RCM RCM j|| s MM MIC MIC Φ seconds RCM MIC M-I Coupler ΣΦ j || Empirical Σ 1½-way LFM-RCM coupling SWM MM MM B s RCM minutes MM Precip W|| , E0 TIM MM RCM RCM RCM j|| s MIC MIC Empirical Σ M-I Coupler ΣΦ vn × B j || MIC TIM Σ ,vn MIC iterate Φ TIM TIM m Convergent, iterative, 1-way TING coupling Auroral Electrodynamics Opgenoorth et al. ‘02 Ionospheric Feedback Polarization Field-Aligned Current Atkinson ’70; Sato ‘78 Two-fluid MHD model of the magnetosphere Electron parallel momentum equation v||e me n0 AR IC v||e en0 E|| bˆ pe 0, t where v||e - electron parallel speed; IC - electron collision frequency; AR - effective collision frequency representing the effects of plasma anomalous resistivity. Density continuity equation n1 n0 v||ebˆ 0, t Current continuity equation 2 E c 2 2 2 2 ˆ 1 i j||b 0 1 i 2 0, v A t where ρi - ion Larmour radius. Model of the auroral ionosphere Density Continuity Equation j|| j|| hot n1 1 Si n 2 , t eh eh where n = n0 + n1 - plasma number density; Si n02 - ionization source maintaining equilibrium density n0 outside the region of auroral precipitations; j|| - field-aligned current; - recombination coefficient. Current Continuity Equation S P E S H E bˆ j|| , where SP and SH are height-integrated ionospheric Pedersen and Hall conductances. “Feedback” Unstable Alfvén Waves Small-Scale Resonator Two resonant cavities Growth rate vs P, E and k Pokhotelov ‘02 Large-Scale Resonator Feedback Instability 125 s 220 s 141 s 235 s 157 s 251 s 173 s 266 s 188 s 281 s 204 s 297 s ENS Ionospheric Alfvén Resonator J J Ne + – Ne2 + – SP + – E Layer E Stable? – + yes no L = 7.25 Streltsov and Lotko ‘02 8.25 670 mV/m “Satellite” Measurements 600 BEW -50 400 -100 200 670 mV/m nT mV/m ENS 0 -150 ENS -200 0 0 50 100 150 BEW 200 distance, km 150 5 100 3 2 PB 50 270 nT 4 (nT)2 km (mV/m)2 km PE j 1 0 0 0 0.05 0.10 0.15 k, km-1 0.20 0.25 80 A/m2 Time Step = 297 s Streltsov and Lotko ‘02 ENS (mV/m) L = 8.25 7.25