Inversion code for HMI vector polarimetric mode

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Inversion code for HMI vector polarimetric mode
J.M. Borrero, S.Tomczyk, T. Darnell, H.
Socas-Navarro, A. Norton, B. Lites, D.
Elmore High Altitude Observatory National Center
for Atmospheric Research
Jan 2005
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How it works ?
J.M.Borrero Jan 2005
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What's the plan ?
Take any IC and make sure it gives a numerical
correct solution.
MELANIE by Socas-Navarro Milne-Eddington
model Non-linear Squares fitting
(Levenberg-Marquardt) Modified SVD by Ruiz Cobo
del Todo Iniesta Numerical derivatives Speed
performance of 30 pixels/min Under ideal
conditions With limited spectral sampling (5-6
wv.positions) -number of tuning positions With
non-simultaneous wv. sampling (oscillations) -
tuning sequence With limited exposure
time(noise) With two-beam polarimetric
acquisition -combination of polarization states
MELANIE by Socas-Navarro Milne-Eddington
model Non-linear Squares fitting
(Levenberg-Marquardt) Modified SVD by Ruiz Cobo
del Todo Iniesta Numerical derivatives Speed
performance of 30 pixels/min Under ideal
conditions With limited spectral sampling (5-6
wv.positions) -number of tuning positions With
non-simultaneous wv. sampling (oscillations) -
tuning sequence With limited exposure
time(noise) With two-beam polarimetric
acquisition -combination of polarization states
The IC must be independent of the initial guess
model.
J.M.Borrero Jan 2005
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Inversion Speed
Non-Iterative algorithms (PCA,ANN) Current
speed 4x10e4 pix/min thermodynamics
neglected improved CPU speed Estimated
speed 10e5 pix/min
Iterative algorithms (Current) Current speed 30
pix/min analytical derivatives initial
parameters optimization thermodynamics
neglected improved CPU speed Estimated speed
200-500 pix/min
Adding 100 CPUs for parallel computing Estimated
speed 2-5x10e4 pix/min Estimated
speed 10e6 pix/min
J.M.Borrero Jan 2005
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Other products
More complex inversions might be possible if -
we manage to get rid of the p-modes (tuning
sequence, temporal average) - we improve the
spectral resolution ( 6 wavelength positions) -
we improve the S/R (spatial temporal
average) Would require Iterative algorithms Would
be only suitable for small ROI (e.gsunspots) Poli
cy inversions done systematically or upon
request ?
Horizonal features - 2 component inversion
using filling factor - can allow to retrieve
field strength rather than flux even in the weak
field regime
Vertical features - inversion including
gradients along the LOS
J.M.Borrero Jan 2005