MI Coupling Physics: Issues, Strategies, Progress William Lotko 1, Peter Damiano 1, Mike Wiltberger 2, John Lyon 1,2, Slava Merkin 3, Oliver Brambles 1, Binzheng Zhang 1, Katie Garcia 3 Dartmouth Founded 1769 The Event Steady SW, IMF B z < 0 SMC interval (in the sense of O’Brien et al, 2002) Data from  Korth et al. (2004)  Waters et al. (2004) One-Fluid LFM Simulations Grid: 53x48x64  200 km  200 km at ionosphere Extract E and B at inner boundary Calculate δB  B - B dip (dipole field) Calculate S   = E x δB·b dip /μ 0, where   1-hour Map S  from LFM inner boundary to ionosphere Compare simulation  PC, J  and S  at ionosphere with SuperDARN-Iridium  Weimer (2005)  DMSP track data The mediating transport processes occur on spatial scales smaller than the grid sizes of the LFM and TIEGCM global models. Energization Regions Paschmann et al., ‘03 Evans et al., ‘77 Conductivity Modifications A 1 R E spatial “gap” exists between the upper boundary of TING (or TIEGCM) and the lower boundary of LFM. The gap is a primary site of plasma transport where electromagnetic power is converted into field-aligned electron streams, ion outflows and heat. Modifications of the ionospheric conductivity by electron precipitation are included in global MHD models via a “Knight relation”; but other crucial physics is missing: –Collisionless dissipation in the gap region; –Heat flux carried by upward accelerated electrons; –Conductivity depletion in downward current regions; –Ion parallel transport  outflowing ions, esp. O +. Issues Challenge: Develop models for subgrid processes using large-scale variables from the global models as causal drivers. The “Gap” Collisionless Dissipation EM Power In  Ions Out Zheng et al. ‘05 Strategy (Four transport models) 1.Current-voltage relation in regions of downward field- aligned current; 2.Ion transport in downward-current and Alfvénic regions; 3.Collisionless Joule dissipation and electron energization in Alfvénic regions – mainly cusp and auroral BPS regions; 4.Ion outflow model in the polar cap (polar wind). Empirical “Causal” Relations r = F O+ = 2.14x10 7 ·S || r = Strangeway et al. ‘05 Advance multifluid LFM (MFLFM) Advance empirical outflow model Develop polar wind outflow model Develop Alfvénic electron precipitation model Priorities DMSP Track Comparisons Ion Outflows Lennartsson et al. ‘04 12 Abe et al. ‘03 12 Superthermal Thermal Poynting Fluxes DC 12 Keiling et al. ‘03 Alfvénic Olsson et al. ‘04 12 Observed Statistical Distributions Develop model for particle energization in Alfvénic regions (scale issues!) Explore frequency dependence of fluctuations at LFM inner boundary Full parallel transport model for gap region (long term) Progress Reconciled E  mapping and parallel Joule dissipation with Knight relation in LFM Power Flow Through the Gap Gap Dissipation Poynting flux S ||m Ionospheric Dissipation with Effect of   Global Electrodynamics   = 0    Alfvénic Ion Energization via Validations of LFM Poynting fluxes with Iridium- SuperDARN events (Melanson) and global statistical results from DE, Astrid, Polar (Gagne) Chaston et al. ‘03 Alfvénic Electron Energization Alfvén Poynting Flux, mW/m 2 Energy Flux Mean Energy mW/m 2 keV  A/m 2 J || 1 Developed and implemented empirical outflow model with outflow flux indexed to EM power and electron precipitation flowing into gap from LFM (S ||  F e|| )