1. Solar Wind and CMEs with the Space Weather Modeling Framework
Bart van der Holst
C. Downs, F. Fang, R. Oran
W. Manchester, I. Sokolov, G. Toth, T. Gombosi
Center for Space Environment Modeling
University of Michigan

2. Outline Space Weather Modeling Framework New: Lower Corona model
New: Corona model with Alfvén wave turbulence
New: Flux Emergence in Convection Zone model
Outlook: Couple it all together
B. van der Holst

3. Space Weather Modeling Framework
Synoptic
Magnetograms
Flare/CME
Observations
Upstream
Monitors
Radars
Magnetometers
In-situ
F10.7 Flux
Gravity
Waves
SWMF Control & Infrastructure
Eruption
Generator
3D Corona
3D Inner
Heliosphere
Global
Magnetosphere
Polar Wind
Inner
Ionospheric
Electrodynamics
Thermosphere
& Ionosphere
Energetic
Particles
Plasmasphere
Radiation
Belts
Lower
Atmosphere
3D Outer
couplers

4. Space Weather Modeling Framework

5. Quantitative Comparison with SOHO for the October 2003 Halloween Storm
Out of equilibrium flux rope superposed on a steady state MHD corona
Total Mass, Observed =1.5x1016 gm Model = 2.2x1016 gm

6. Observed vs. Simulated Solar Wind and IMF near Earth (10o off)
vX [km/s]
vX [km/s]
n [cm-3]
n [cm-3]
Simulated CME arrives 4.8 hours early. Solar wind speed is almost perfect! Density is within range. Magnetic field variation has right amplitude but sign and phase differ.
lg T [K]
lg T [K]
BX [nT]
BX [nT]
BY [nT]
BY [nT]
BZ [nT]
BZ [nT]
Hours from 00:00 Oct 29 6

7. Need for improvement
Coronal model was based on a reduced, spatially varying adiabatic index for the heating and acceleration of the plasma.
In good agreement with the ambient solar wind observed at 1AU, but it is not self-consistent and distorts the physics, especially at CME shocks.
CME is not self-consistent, but a superposed flux rope model.

8. Lower Corona Improved thermodynamics: Electron heat conduction
Optically thin radiative losses
Exponential heating function, in active regions transition to heating proportional to magnetic field strength
Chromosphere boundary (T=20000K, ne=1012)
Resolve transition region
Ability to synthesize line-of-sight images in the EUV and X-ray regime

9. EUV and X-ray LOS images for CR1913
EIT 171Å
EIT 195Å
EIT 284Å
SXT AlMg
Old SC model
synthesis
New LC model
synthesis
Observation:
Aug 27, 1997

10. Streamer structure for CR1913
PFSS model
Old SC model
New LC model
Top view
Earth
Centered
view
Closed field lines structures are stressed by heating near surface and subsequent redistribution via heat conduction

11. SXT response for CR1913
3D topology of T=1.6MK
LOS synthesis of SXT AlMg response
Connection of the hot, closed field line regions overlay the inversion lines on the surface and correspond to the x-ray emission.

12. Alfvén Wave Turbulence
Alfvén wave turbulence has been suggested in the past as a possible mechanism both to heat and accelerate the solar wind plasma.
Hinode observations suggest that the energy input is sufficient for heating and acceleration (e.g. de Pontiue et al. 2007).
Wind acceleration: work done by wave pressure force
Coronal heating: Alfvén wave dissipation at the ion cyclotron resonance.

13. 4D Alfvén wave model
Wave kinetic approach for describing the transport of Alfvén waves in a background MHD plasma.
The intensity of the (low frequency) Alfvén wave turbulence is a 4D (3D space, 1D frequency) problem:
Advection in
Space
Advection in
frequency
Dissipation at
Ion Cyclotron
2-way coupling of wave turbulence to MHD plasma background:
Wave pressure deposit momentum to the background flow
background solution determines the wave propagation and spectral evolution.

14. Model input Magnetogram driven potential field extrapolation.
Spectrum: user input, but in current work we assume a Kolmogorov spectrum as the initial condition, i.e.
Specify Alfvén wave pressure at the solar base:
Given solar wind expansion factor from PFSS model,
Given velocity at 1AU based on WSA model,
Impose energy conservation along the field lines to determine the Alfvén wave pressure at 1RS (Suzuki, 2006).
In-going Alfvén waves at 1RS are absorbed.

15. Result for CR2029 Wave dissipation not yet in place, so that:
(1) Solar wind speed too high
(2) Conversion rate of wave energy into heating is too low
Compared to previous SC model (spatially reduced adiabatic index), we can now describe the corona self-consistent, without distorting the shock wave compression ratio

16. Convection Zone
Atmosphere with coronal heating and radiative losses (Abbett, 2007)
OPAL EOS
Vertical velocity at photospheric level shown in gray scale
Magnetic field concentrated in the intergranular lanes

17. Flux Emergence In the Corona
Buoyant flux rope initially at 1500km below the photosphere
3D view at 2 minutes after initialization

18. Flux Emergence In the Corona
Convective down flow tries to drag flux rope downwards, up flow helps the flux to emerge, thus segmentation of rope

19. Outlook New radiation MHD package for Convection Zone
Coupling of Convection Zone to Global Heliosphere
Allows physically consistent CME eruptions into a physically consistent solar wind