1. Understanding Magnetic Eruptions on the Sun and their Interplanetary Consequences A Solar and Heliospheric Research grant funded by the DoD MURI program George H. Fisher, PI Space Sciences Laboratory University of California, Berkeley

2. Institutions of Solar Multidisciplinary University Research Initiative Team UC Berkeley Big Bear Solar Observatory (NJIT) Drexel University Montana State University Stanford University UC San Diego University of Colorado University of Hawaii University of New Hampshire

3. Goal Develop a state-of-the-art, observationally tested 3-D numerical modeling system for predicting magnetic eruptions on the Sun and the propagation of Coronal Mass Ejections (CMEs).

4. Approach Perform in-depth, coordinated space and ground based observations of magnetic eruptions and Coronal Mass Ejection (CME) propagation Understand the physics of how magnetic eruptions are triggered and powered Develop numerical models for the initiation and propagation of CMEs and the acceleration of Solar Energetic Particles (SEPs) Couple together the observationally tested models of the Sun and Heliosphere

5. Overview of Solar MURI 1.Active Region Emergence: Fisher & Abbett (UCB), LaBonte, Jing Li, & Mickey (UH), Canfield & Regnier (MSU), Liu (Stanford), Gallagher,Moon, Wang & Goode (BBSO) 2.Effects of Large Scale Field and Solar Cycle Evolution: Hoeksema, Scherrer, & Zhao (Stanford), Ledvina & Luhmann (UCB), Martens (MSU), Goode, Wang & Gallagher (BBSO) 3.Inner Corona: Forbes (UNH), MacNeice (Drexel), Abbett, Ledvina, Luhmann & Fisher (UCB), Kuhn & H. Lin (UH), Canfield & Longcope (MSU), Hoeksema, Scherrer & Zhao (Stanford) 4.Outer Corona, Solar Wind, SEPs: Odstrcil (CU), Jackson, Dunn & Hick (UCSD), MacNeice (Drexel), Luhmann & R. Lin (UCB), Lee (UNH) 5.Geoeffects: Luhmann & R. Lin (UCB), Odstrcil (CU), Hoeksema & Zhao (Stanford)

6. MURI mini-workshops related to CME initiation: Using vector magnetogram data in MHD simulation and other theoretical models (April 29, G.H. Fisher & R.C. Canfield, Berkeley) Well defined numerical experiments for CME eruption mechanisms (May 14-16, T.J. Forbes, Durham NH)

7. UNH MURI Workshop: Planned Numerical Experiments: 1. The emerged bipole 3-d Emerged Bipole: Form flux-rope in simulated corona by converging footpoints of coronal fields. computational domain is 3-d non-periodic box with high  = 10?) on bottom boundary, w/stratification such that  << 1 within lower part of simulation volume. initial condition (IC) has volume-filling dipole field. impose incompressible converging flows on bottom boundary.

8. 3d emerged bipole (cont’d) initial magnetic field ought to be sheared, such that some component of the magnetic field is parallel to the magnetic neutral line at the bottom boundary; or if initial magnetic field is unsheared (potential?), imposed flow should have non-zero vorticity, to ensure some component of magnetic field is tangential to the magnetic neutral line on the bottom boundary primary goal is to form flux rope; subsequent efforts to erupt flux rope envisioned upon attainment of flux rope in corona this experiment involves some modification of existing codes. Critical issue: 3-d necessary (no 2.5-d, or periodicity)

9. 2. The 3-d Emerging Bipole: Flux rope in coronal volume via emergence of a pre- existing twisted flux tube from a region of high  to low  IC: buoyantly unstable horizontal twisted flux tube immersed in high-  plasma at base of gravitationally stratified 3-d box. Follow rise of twisted flux tube from deep in convection zone through photosphere into corona. Critical issue: initial position of tube cannot be too near surface, as flux tube curvature matters. Unspecified parameter: degree of twist in emerging tube. Twist too high perhaps prevents mass drainage, hampering emergence; twist too low does not give true flux rope in corona.

10. 3d emerging bipole (cont’d) Unspecified parameter: Magnetic field configuration in corona prior to flux rope emergence. Initial runs w/field-free corona envisioned. As above, primary goal is to get flux rope in corona; subsequent efforts to attain eruption envisioned after attainment of primary. As above, some modification of existing codes necessary.

11. 3. Bipole emergence in 3d multi- polar field Emerge one flux tube into into background magnetic field; sheared arcade/flux rope formation by reconnection between emerging flux and pre-existing flux.

12. Bipole emergence in multi-polar field (cont’d) IC: buoyantly unstable flux tube immersed in high-  plasma at base of gravitationally stratified 3-d box with background magnetic field configuration composed of a pre-emerged flux tube and large scale “restraining field”, and form sheared arcade/flux rope by reconnection between the two flux tubes. Critical issue: without restraining field, reconnected flux expected to rise to top of computational volume in non-explosive manner.

13. Bipole emergence in multi-polar field (cont’d) Primary goal is attainment of sheared arcade/flux rope in corona; subsequent effort to attain eruption envisioned. In one effort to attain eruption, additional polarity will be added to restraining field to make it quadrupolar. Unspecified parameter: twist in either pre-emerged or newly-emerging flux ropes. Presence of twist might either enhance or diminish storage of energy in the field, and hence likelihood of eruption.

14. Solar MURI Vector Magnetogram Mini-Workshop Using Vector Magnetograms in Theoretical Models: Plan of Action

15. Overview of the plan Phase I 1.Analyze available data for 1998 May 1 event 2.Construct coronal magnetic equilibria 3.Develop velocity inversion methods 4.Test velocity inversion methods 5.Study a second (simpler) event – May 12, 1997 Phase II 1.Carry out MHD simulations 2.Couple coronal and IP codes Phase III 1.Validation of modelling using available solar and IP data

16. Analyze available data for 1998 May 1 event 1.Generate a sequence of IVM magnetograms for the 1998 May 1 23:40 UT halo CME event (AR 8210), time cadence ~15 min (too slow ?), before, during, and after eruption. (Regnier) 2.Estimate the magnetic field uncertainties.(Metcalf, Leka) 3.Determine line of sight and transverse velocities. (Welsch, Metcalf) 4.Analyze the global solar (Li, Liu) and IP (Li, Luhmann) context (spatial, temporal) of this event, time scale ~ several days, including previous and following events. 5.Make an instrument vs time array on WWW (Li)

17. Construct coronal magnetic equilibria 1.Build force-free magnetic field models for each magnetogram, combined with a potential extrapolation of MDI data. (Regnier) 2.Build magnetostatic models from the same magnetograms (Heinemann). 3.Compare force-free magnetic field models to available coronal imaging data (Canfield, Metcalf) 4.Compare connectivity of force-free models to that of point charge models (Regnier, Longcope, Leka)

18. Develop velocity inversion methods 1.Use vertical component of induction equation to derive velocity fields (Longcope, Fisher, Welsch) 2.Constrain the solutions by minimizing total kinetic energy (ditto)

19. Test velocity inversion methods 1.Generate fake magnetogram sequences from the MHD simulations (Abbett, Fisher) 2.Use velocity inversion techniques to infer velocities from these sequences (ditto + Welsch) 3.Compare photospheric boundary velocities from the simulation to those inferred from the inversion (same as 2) 4.Explore implications of magnetogram uncertainties through Monte Carlo methods (same as 2). 5.Compare velocities from the inversion to IVM observations (Welsch, Metcalf, Abbett, Fisher)

20. Study a second (simpler) event (Liu) 1.Identify a simpler solar and IP event for analysis (1997 May 12 halo CME in AR8038 ?). 2.Produce a vector magnetogram (Solar Flare Telescope / Mitaka ?) sequence for this event. 3.Carry out an analysis parallel to that of the 1998 May 1 event (no velocity observations available – or use LCT methods for v_t, MDI for v_l?) (Liu + Welsch)

21. Carry out MHD simulations Do Zeus AMR simulations using real magnetic field data near time of CME using synoptic magnetic field solutions as boundary condition. (Berkeley team members) Couple coronal and interplanetary codes (Abbett, Ledvina, Odstrcil)