J/ApJ/752/126 Modeling the magnetic field in the solar corona (Yamamoto+, 2012)
Preprocessing magnetic fields with chromospheric longitudinal fields.
Yamamoto T.T., Kusano K.
<Astrophys. J., 752, 126 (2012)>
=2012ApJ...752..126Y 2012ApJ...752..126Y
ADC_Keywords: Sun ; Magnetic fields
Keywords: Sun: chromosphere; Sun: photosphere; Sun: surface magnetism
Abstract:
Nonlinear force-free field (NLFFF) extrapolation is a powerful tool
for the modeling of the magnetic field in the solar corona. However,
since the photospheric magnetic field does not in general satisfy the
force-free condition, some kind of processing is required to
assimilate data into the model. In this paper, we report the results
of new preprocessing for the NLFFF extrapolation. Through this
preprocessing, we expect to obtain magnetic field data similar to
those in the chromosphere. In our preprocessing, we add a new term
concerning chromospheric longitudinal fields into the optimization
function proposed by Wiegelmann et al (2006SoPh..233..215W 2006SoPh..233..215W). We
perform a parameter survey of six free parameters to find minimum
force- and torque-freeness with the simulated-annealing method.
Analyzed data are a photospheric vector magnetogram of AR 10953
observed with the Hinode spectropolarimeter and a chromospheric
longitudinal magnetogram observed with SOLIS spectropolarimeter. It is
found that some preprocessed fields show the smallest force- and
torque-freeness and are very similar to the chromospheric longitudinal
fields. On the other hand, other preprocessed fields show noisy maps,
although the force- and torque-freeness are of the same order. By
analyzing preprocessed noisy maps in the wave number space, we found
that small and large wave number components balance out on the
force-free index. We also discuss our iteration limit of the
simulated-annealing method and magnetic structure broadening in the
chromosphere.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 47 86 Free parameter pairs
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See also:
J/ApJS/169/439 : Models of solar magnetic structures (Socas-Navarro, 2007)
J/A+A/432/1063 : Analysis of inner solar corona in EUV (Lanzafame+, 2005)
http://solis.nso.edu/ : National Solar Observatory NISP/SOLIS
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Num [0/85] Parameter combination number
4- 5 I2 [-] logt0 [-4/2] Log of coefficient of the initial pseudo
temperature; Tinit=t0*Linit
7- 12 F6.4 --- dT [995/0.9995] Temperature cooling factor:
new T = old T * dT
14- 15 I2 [-] logmu3 Log of coefficient of L3
17- 18 I2 [-] logmu4 Log of coefficient of L4
20- 21 I2 [-] logmu5 Log of coefficient of L5 (See equation (20))
23- 25 I3 --- Seed [3/259] Random number seed
27 I1 --- cnv [0/1] Calculation convergence code; 1=converged
29- 37 E9.4 --- r1 Ratio of L1init/L1finish
39- 47 E9.4 --- r5 Ratio of L5init/L5finish
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Feb-2014