Inferring a photospheric velocity field from a sequence of vector magnetograms: The Minimum Energy Fit 

Dana Longcope Submitted: 20040517 09:42
We introduce a technique for inferring a photospheric velocity from a sequence of vector magnetograms. The technique, called The Minimum Energy Fit, demands that the photospheric flow agree with the observed photospheric field evolution according to the magnetic induction equation. It selects, from all consistent flows, that with the smallest overall flow speed by demanding that it minimize an energy functional. Partial or imperfect velocity information, obtained independently, may be incorporated by demanding a velocity consistent with the induction equation which minimizes the squared difference with flow components otherwise known. The combination of low velocity and consistency with the induction equation are desirable when using the magnetogram data and associated flow as boundary conditions of a numerical simulation. The technique is tested on synthetic magnetograms generated by specified flow fields and shown to yield reasonable agreement. It also yields believable flows from magnetograms of NOAA AR8210 made with the Imaging Vector Magnetogram at the Mees Solar Observatory.
Authors: D.W. Longcope
Projects: None

Publication Status: ApJ (in press)
Last Modified: 20040517 09:42


