1. 1 ModelModelerU U (P) U (F) UUUU  U (P)  U (F) NLFFF J. McTiernan 8e327e321e325e314e31~0 Mod. Virial T. Metcalf 1e33-3e32~0--7e31 MCC/ IVM MCC/MDI-S MCC/MDI-L G. Barnes, C. Beveridge, D. Longcope ---------------1e302e303e30 FEF/ ILCT FEF/ LCT B. Welsch ------5e311e319e31~0-4e31+1e31 MEF R. Belur, D. Longcope ---4e31-- May 1998 “Pre-Event” Session Recap Coronal energy loss estimate during magnetogram interval: <~1e+31 erg GOAL: compare estimates of magnetic free energy in AR 8210, to improve our understanding of coronal energy release.

2. 2 Lessons Learned 1.We distinguished between free magnetic energy, and “usable” free magnetic energy. –Through reconnection, flares probably dissipate current sheets, not volume currents. So the “free energy” stored in volume currents isn’t “usable.” (CMEs might differ in this regard?) –MCC claims to estimate only current sheet energies, while NLFFF / Virial include volume currents. –Hence, MCC = lower bound, & NLFFF/Virial = upper bound? Our coronal energy loss estimates fell between these two.

3. 3 Lessons Learned, cont’d: 1.Many versions of “the” potential field matching a given B n exist, and can differ substantially in energy. –Some standardization would be desirable. 2.The relationship between free magnetic energy & coronal emission is not obvious. –It’s not clear that a measured increase in free energy should result in subsequent energy release immediately.