Issues

1
M-I Coupling Physics Issues, Strategy, Progress
William Lotko, John Gagne, David Murr, John
Lyon, Paul Melanson
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.

EM Power In ? Ions Out
Empirical Causal Relations
KnightDissipation
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, doi10.1029/2002JA009420,
2003 ? Cran-McGreehin, A.P., and A.N. Wright,
Current-voltage relationship in downward
field-aligned current region, J. Geophys. Res.
110, A10S10, doi10.1029/2004JA010870, 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), 22352249, 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
Earths H and O outflow rates in the 15-eV to
33-keV energy range, J. Geophys. Res. 109,
A12212, doi10.1029/2004JA010690, 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,
doi10.1029/2004JA010829, 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, doi10.1029/2004JA010995, 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
Ionospheric Parameters(issues!)
Where does the mass go?
Percent Changein Mass Density
Alfvénic Electron Energization
Alfvénic Ion Energization
Northern Outflow
1200 UT
Chaston et al. 03
Keiling et al. 03
Lennartsson et al. 04