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M-I Coupling Physics: Issues, Strategy, Progress William Lotko, David Murr, John Lyon, Paul Melanson, Mike Wiltberger The mediating transport processes.

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Presentation on theme: "M-I Coupling Physics: Issues, Strategy, Progress William Lotko, David Murr, John Lyon, Paul Melanson, Mike Wiltberger The mediating transport processes."— Presentation transcript:

1 M-I Coupling Physics: Issues, Strategy, Progress William Lotko, David Murr, John Lyon, Paul Melanson, Mike Wiltberger The mediating transport processes occur on spatial scales smaller than the grid sizes of the LFM and TING/TIEGCM global 2.Ion transport in downward-current and Alfvénic regions; Progress Energization Regions Paschmann et al., ‘03 Evans et al., ‘77 Conductivity Modifications Dartmouth founded 1769 Collisionless Dissipation Alfvénic Electron Energization Energy Flux Mean Energy J || mW/m 2 keV  A/m 2 Alfvén Poynting Flux, mW/m 2 Chaston et al. ‘03 EM Power In  Ions Out Zheng et al. ‘05 Implement and advance multifluid LFM (MFLFM!) Implement CMW (2005) current-voltage relation in downward current regions Include electron exodus from ionosphere  conductivity depletion Accommodate upward electron energy flux into LFM Where does the mass go? Alfvénic Ion Energization Lennartsson et al. ‘04 Keiling et al. ‘03 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 the electron precipitation are included 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 +. Develop model for particle energization in Alfvénic regions (scale issues!) Need to explore frequency dependence of fluctuation spectrum at LFM inner boundary Full parallel transport model for gap region (long term) Advance empirical outflow model Issues Reconciled E  mapping and collisionless Joule dissipation with Knight relation in LFM Developed and implemented empirical outflow model with outflow flux indexed to EM power and electron precipitation flowing into gap from LFM (S ||  F e|| ) Validations of LFM Poynting fluxes with Iridium/SuperDARN events (Melanson thesis) and global statistical results from DE, Astrid, Polar (Gagne thesis) Priorities 3.Collisionless Joule dissipation and electron energization in Alfvénic regions – mainly cusp and auroral BPS regions; Strategy (Four transport models) 1.Current-voltage relation in regions of downward field-aligned current; 4.Ion outflow model in the polar cap (polar wind). The “Gap” Empirical “Causal” Relations r = F O+ = 2.14x10 7 ·S || r = Strangeway et al. ‘05 Cosponsored by NASA HTP Challenge: Develop models for subgrid processes using dependent, large-scale variables available from the global models as causal drivers. Effects on MI Coupling (issues!) NorthSouth 8.5 simulation hours A VERAGE I ON N UMBER F LUXES LFM with H + Outflow (8 hours of CISM “Long Run”) compared with Polar Perigee Data (6 months Austral Summer) Oct 97 – Mar 98 Polar perigee DUSK 2  ions/s3  ions/s 2-3  ions/s FLUENCE Log (Flux, # / m 2 -s) Log (Flux, # / m 2 -s) Lennartsson et al. 2004


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