1. Feb. 2006HMI/AIA Science Team Mtg.1 Determining the 3D Magnetic Field Geometry A. A. van Ballegooijen, E. E. DeLuca, M. Bobra Smithsonian Astrophysical Observatory Cambridge, MA

2. Feb. 2006HMI/AIA Science Team Mtg.2 Field Extrapolation AIA Objective #1 (energy input, storage, and release) requires knowledge of 3D coronal magnetic structure and dynamics. One approach is to “extrapolate” observed vector fields into the corona, using nonlinear force free field (NLFFF) modeling: Practical difficulties: nonlinear problem limited sensitivity of B trans 180-degree ambiguity photosphere is not force free (Bt-phot ≠ Bt-corona) At present, there is no good method for extrapolating strongly sheared fields.

3. Feb. 2006HMI/AIA Science Team Mtg.3 Developing Extrapolation Methods Extrapolating photospheric vector fields does not work well for filament channels where sheared field is “elevated” into chromosphere. Need observational constraints on chromospheric fields. Need to include non-force-free photospheric conditions into models. Test case (see poster): -- Add vertical force at z = 2 Mm to simulate non-force-free condition. -- Construct 3D model (“A”) with the highly sheared field. -- Extract “observed” chromospheric vector field (z = 4 Mm). -- Reconstruct 3D field (“B”) by extrapolating chromospheric field (uses magneto-frictional relaxation and injection of horizontal field at z = 0 based on the error ΔB = B obs – B model in chromosphere). -- Method gives a good fit to “observed” vector field.

4. Feb. 2006HMI/AIA Science Team Mtg.4 Developing Extrapolation Methods Test case: chromospheric vector field (blue=“observed”, black=model) A: B: BBSO+MDI, 2005/10/10, 17:30UT

5. Feb. 2006HMI/AIA Science Team Mtg.5 Use H-alpha Fibrils?

6. Feb. 2006HMI/AIA Science Team Mtg.6 NLFFF Modeling Tasks Develop methods/codes for extrapolating vector fields in spherical geometry, covering large area on the Sun (reduce the effects of side boundaries); models must extend to large height ~ 2.5 Rsun. Develop methods for including observational constraints on chromospheric fields and effects of non-force-free photosphere. Test NLFFF methods/codes using synthetic vector-field data. Test NLFFF models using TRACE data. Can models reproduce the observed coronal loop structures? Develop quantitative methods for comparing 3D models with observed coronal loops and Hα filaments.