Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Estimating Electric Fields from Vector Magnetogram Sequences   Determining the electric field (E-field) distribution on the Sun's
photosphere is essential for quantitative studies of how energy flows from the
Sun's photosphere, through the corona, and into the heliosphere. This E-field
also provides valuable input for data-driven models of the solar atmosphere and
the Sun-Earth system. We show how Faraday's Law can be used with observed
vector magnetogram time series to estimate the photospheric E-field, an
ill-posed inversion problem. Our method uses a "poloidal-toroidal
decomposition" (PTD) of the time derivative of the vector magnetic field. The
PTD solutions are not unique; the gradient of a scalar potential can be added
to the PTD E-field without affecting consistency with Faraday's Law. We present
an iterative technique to determine a potential function consistent with ideal
MHD evolution; but this E-field is also not a unique solution to Faraday's Law.
Finally, we explore a variational approach that minimizes an energy functional
to determine a unique E-field, similar to Longcope's "Minimum Energy Fit". The
PTD technique, the iterative technique, and the variational technique are used
to estimate E-fields from a pair of synthetic vector magnetograms taken from an
MHD simulation; and these E-fields are compared with the simulation's known
electric fields. These three techniques are then applied to a pair of vector
magnetograms of solar active region NOAA AR8210, to demonstrate the methods
with real data.

23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph