1. Finding the Flow Field Need flow information! –ideal evolution of coronal B(x,y,z,t) determined entirely by B(x,y,z,0) and v(x,y,0) – get v wrong and get topology wrong! –energy flux into corona via Poynting flux: S = (v x B) x B Contending methods are: 1. Local Correlation Tracking (LCT) 2. Minimum Energy Functional (MEF)

2. Minimum Energy Functional We want v to solve induction eqn’s z-comp: Solution is underdetermined by data! Longcope: try minimizing “kinetic energy!”

3. Local Correlation Tracking Essentially, relate signal in “before” and “after” images to find the best shift. DISAD: no info about z-comp. of v! DISAD: v not necess. consistent w/physics!

4. Testing MEF & LCT: Use MHD simulations from Abbett et al. and Magara w/known v & B Compare inverted velocities with “truth.”

5. MEF

6. MEF zoom

7. Fisher’s LCT

8. November’s LCT

9. Preliminary results: MEF outperforms our LCT codes –marginally! All routines make notable mistakes! –LCT fails in regions of strong –MEF finds asymmetric solutions from symmetric data

10. Take-home points: –Problems exist with LCT! - our community needs to know its limits –MEF is just beginning to be understood -smoothings/thresholds alter results -still, might be our best bet for finding v -This work is still in progress!