Issues

1. M-I Coupling Physics: Issues, Strategy, Progress William Lotko, John Gagne, David Murr, John Lyon, Paul Melanson 1010 O+ / m2-s Dartmouth 0 2 4 6 8 10 founded 1769 FO+ = 2.14x107·S||1.265 The “Gap” r = 0.755 r = 0.721 IMF No outflow Zheng et al. ‘05 Global Effects of O+ Outflow With outflow Paschmann et al., ‘03 IMF Energy Flux mW/m2 T > 1 keV  > 0.5 Mean Energy n < 0.2/cm3 P < 0.01 nPa keV J|| A/m2 Alfvén Poynting Flux, mW/m2 Cosponsored by NASA SECTP • Issues • A 2 RE spatial “gap” exists between the upper boundary of TING and TIEGCM and the lower boundary of LFM. • The gap is a primary site of plasma transport where electromagnetic power is converted into field-aligned electrons, ion outflows and heat. • Modifications of the ionospheric conductivity by the electron precipitation is included in global models via the “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+. Empirical “Causal” Relations EM Power In  Ions Out “Knight”Dissipation Strangeway et al. ‘05 • Progress • Reconciled E mapping and collisionless Joule dissipation with Knight relation in LFM • Developed and implemented empirical outflow model – O+ flux indexed to EM power and electron precipitation flowing into gap from LFM (S|| Fe||) • Initiated validation of LFM Poynting fluxes with global statistical results from DE, Astrid, Polar and Iridium/SuperDARN events (Gagne thesis + student poster by Melanson) Conductivity Modifications The mediating transport processes occur on spatial scales smaller than the grid sizes of the LFM and TING/TIEGCM global models. Challenge: Develop models for subgrid processes using the dependent, large-scale variables available from the global models as causal drivers. Evans et al., ‘77 Chaston, C.C., J. W. Bonnell, C. W. Carlson, J. P. McFadden, R. E. Ergun, and R. J. Strangeway, Properties of small-scale Alfvén waves and accelerated electrons from FAST, J. Geophys. Res. 108(A4), 8003, doi:10.1029/2002JA009420, 2003  Cran-McGreehin, A.P., and A.N. Wright, Current-voltage relationship in downward field-aligned current region, J. Geophys. Res. 110, A10S10, doi:10.1029/2004JA010870, 2005  Evans, D.S., N. Maynard, J. Trøim, T. Jacobsen, and A. Egeland, A., Auroral vector electric field and particle comparisons 2. Electrodynamics of an arc, J. Geophys. Res. 82(16), 2235–2249, 1977  Keiling, A., J.R. Wygant, C.A. Cattell, F.S. Mozer, and C.T. Russell, The global morphology of wave Poynting flux: Powering the aurora, Science 299, 383-386, 2003  Lennartsson, O.W., and H.L. Collin, W.K. Peterson, Solar wind control of Earth’s H+ and O+ outflow rates in the 15-eV to 33-keV energy range, J. Geophys. Res. 109, A12212, doi:10.1029/2004JA010690, 2004  Paschmann, G., S. Haaland and R. Treumann, Auroral Plasma Physics, Kluwer Academic Publishers, Boston/Dordrecht/London, 2003  Strangeway, R.J., R. E. Ergun, Y.-J. Su, C. W. Carlson, and R. C. Elphic, Factors controlling ionospheric outflows as observed at intermediate altitudes, J. Geophys. Res. 110, A03221, doi:10.1029/2004JA010829, 2005  Zheng, Y., T.E. Moore, F.S. Mozer, C.T. Russell and R.J. Strangeway, Polar study of ionospheric ion outflow versus energy input, J. Geophys. Res. 110, A07210, doi:10.1029/2004JA010995, 2005 • Priorities • Implement multifluid LFM (!) • Implement CMW (2005) current-voltage relation in downward currents • Include electron exodus from ionosphere  conductivity depletion • Accommodate upward electron energy flux into LFM • Advance empirical outflow model • Develop model for particle energization in Alfvénic regions (scale issues!) • Need to explore frequency dependence of fluctuation spectrum at LFM inner boundary • Parallel transport model for gap region (long term) Energization Regions • Strategy • (four transport models) • Current-voltage relation in regions of downward field-aligned current; • Electron energization and collisionless Joule dissipation in Alfvénic regions – mainly cusp and the auroral BPS regions; • Ion transport in regions 1 and 2 above; and • Ion outflow in the polar cap, essentially a polar wind. Equatorial plane Where does the mass go? Percent Changein Mass Density Ionospheric Parameters(issues!) Alfvénic Electron Energization Alfvénic Ion Energization Northern Outflow 12:00 UT Chaston et al. ‘03 Keiling et al. ‘03 Lennartsson et al. ‘04