AR 8210: “Live & Let Die”? Or, “Never Say Never Again”?

Several techniques exist to determine flows from magnetograms, to drive coronal models.

• Time series of vector magnetograms can be used with:– FLCT, ILCT (Welsch et al. 2004), – MEF (Longcope 2004), – MSR (Georgoulis & LaBonte 2006), – DAVE (Schuck, 2006), or – LCT (e.g., Démoulin & Berger 2003)

to find

• Several methods have been used with AR 8210 data, but not on the same magnetograms / same cadence, etc. Standardizing data & comparing results would be good.

)B (-or , )B - (v fzhzhz uvB

In ideal MHD, photospheric flows move mag-netic flux with a flux transport rate, Bnuf.

hnhnfn vBB Bvu −=

Demoulin & Berger (2003):Apparent motion of flux on a surface can arise from horizontal and/or vertical flows.

In either case, uf represents “flux transport velocity.”

(1)

Magnetic diffusivity also causes flux transport, as field lines can slip through the plasma.

• Even non-ideal transport can be represented as a flux transport velocity.

• Quantitatively, one can approximate 3-D non-ideal effects as 2-D diffusion, in Fick’s Law form,

nideal-nonn Bç~B ∇−u

Some LCT vectors flip as difference images fluctuate!