1. Can the coronal field’s susceptibility to emergence-induced eruption be estimated? SSPVSE Discussion Group B, Wed., 19 Oct. 2005 B. Welsch, Space Sciences Lab, UC-Berkeley Flux emergence might induce flares and CMEs: sufficient, but not necessary, condition (?). Can this relationship be understood well enough to allow “susceptibility estimation”?

2. Flux emergence perturbs the coronal field, 1: close-up of AR 10486 on Oct 27 at 1:35UT 3D images show specific features of the magnetic field topology of AR10486. Field lines with different colors represent the four distinct flux systems. What happens as AR10488 continues to emerge on this day? Images courtesy I. Roussev (SHINE, 2005)

3. 32 hours later The emergence of AR10488 results in the appearance of more null points in the corona! There are more magnetic flux systems of interest now, and therefore more colors… Images courtesy I. Roussev (SHINE, 2005) Flux emergence perturbs the coronal field, 2: close-up of AR 10486 on Oct 28 at 9:35UT

4. Emergence alters both the potential and actual fields, but the relation between changes in the two is unclear. Coronal field, B, should evolve toward lower energy state  “goal” field. Q: Which is the true goal field? B (P), B (PFSS), or B (LFFF) ?

5. Emergence alters both the potential and actual fields, but the relation between changes in the two is unclear. Coronal field, B, should evolve toward lower energy state  “goal” field. Q: Which is the true goal field? B (P), B (PFSS), or B (LFFF) ? We can model B (P), B (PFSS), and B (LFFF) but we can’t necessarily model B (cf., Q# 1). Q: Which changes in B (P), B (PFSS), or B (LFFF) matter, if any? Topology? Energy?

6. Perturbation to PFSS topology from flux emergence can be modelled. PFSS field evolves due to emerging active region from ANMHD simulations. Analogously, could impose simulated flux emergence into actual synoptic magnetogram. Courtesy Y. Li et al. (fall AGU, 2001)

7. One could conduct Monte Carlo simulations of flux emergence into a synoptic magnetogram. Flux emergence: Hale-like; where ARs already exist (K.Harvey) Q: Which changes matter?  open ?  cl ?  E?  (footpoint)?

8. Evaluating topological changes to PFSS due to flux emergence is not trivial. Quantifying changes in footpoints requires field line integration (time consuming). Q: Could changes in PFSS harmonic expansion coefficients, g i and h i, be a proxy for changes in PFSS topology? –If so, {dg i /dt, dh i /dt} would correlate with CMEs. –These data are on-line (KPNO, etc.), but such an analysis has not been performed.

9. Q: Do changes in “goal field” energy matter? Q: Does a sudden drop in the energy E (P) of B (P) mean more free energy is available? Q: What does a sudden rise in E (P) mean? –Actual energy (& free energy) probably scale with potential field energy.

10. Conclusion: physics-based characterization of suscepti- bility to eruption due to flux emergence is possible. Quantitative modeling has not been done. –cf., qualitative models by Luhmann et al. Feasibility (computational resources) and utility (predictive capability) are uncertain. (Good project for a student?)

11. Emerging ARs are enclosed by a separatrix surface, which generally has a current sheet. Longcope et al. (2005) analyzed such an emergence and showed new connections form after ~24 hours.

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