Electron Density Reconstruction of Solar Coronal Mass Ejections Based on Genetic Algorithm: Method and Application. (arXiv:1902.06953v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Dai_X/0/1/0/all/0/1">Xinghua Dai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_H/0/1/0/all/0/1">Huaning Wang</a>
We present a new method to reconstruct three dimensional density of Coronal
Mass Ejection (CME) based on genetic algorithm (GA), namely genetic
reconstruction method (GRM). At first, a model “CME” is constructed to produce
synthetic CME images for the genetic reconstruction. Then the method is applied
to coronagraph data from SOHO, STEREO-A and B on September 30th, 2013. In
comparison with the existing methods for density reconstruction, GRM obtain
global optimization of CME electron distribution. On the other hand, GRM
decreases the difficulty of reconstruction by calculating electron number of
every CME pixel in one of the view angles. Then the electrons are randomly
redistributed along each line of sight (LOS) of CME pixel. Genetic operators
named “crossover” and “mutation” are employed to optimize the electron
distribution. Brightness of each pixel are recalculated through mechanism of
Thomson scattering in multiple view angles. Genetic operator named “selection”
is then employed to hold better distributions and eliminate the worse
distributions according to fitness of recalculated brightness to the observed
brightness. Such process may iterate through hundreds of times to obtain
globally optimized electron distributions. We compare the reconstructed
brightness with observation to show the availability of GRM. Results of GRM are
also compared with those of polarimetric reconstruction and forward modeling
for the method availability. We further apply the reconstructed CME into Space
Weather Modeling Framework (SWMF) to obtain evolution of interplanetary CME and
its geo-effectiveness. Time difference of the CME arrival between ACE
measurement and SWMF simulation is less than 5 hours.
We present a new method to reconstruct three dimensional density of Coronal
Mass Ejection (CME) based on genetic algorithm (GA), namely genetic
reconstruction method (GRM). At first, a model “CME” is constructed to produce
synthetic CME images for the genetic reconstruction. Then the method is applied
to coronagraph data from SOHO, STEREO-A and B on September 30th, 2013. In
comparison with the existing methods for density reconstruction, GRM obtain
global optimization of CME electron distribution. On the other hand, GRM
decreases the difficulty of reconstruction by calculating electron number of
every CME pixel in one of the view angles. Then the electrons are randomly
redistributed along each line of sight (LOS) of CME pixel. Genetic operators
named “crossover” and “mutation” are employed to optimize the electron
distribution. Brightness of each pixel are recalculated through mechanism of
Thomson scattering in multiple view angles. Genetic operator named “selection”
is then employed to hold better distributions and eliminate the worse
distributions according to fitness of recalculated brightness to the observed
brightness. Such process may iterate through hundreds of times to obtain
globally optimized electron distributions. We compare the reconstructed
brightness with observation to show the availability of GRM. Results of GRM are
also compared with those of polarimetric reconstruction and forward modeling
for the method availability. We further apply the reconstructed CME into Space
Weather Modeling Framework (SWMF) to obtain evolution of interplanetary CME and
its geo-effectiveness. Time difference of the CME arrival between ACE
measurement and SWMF simulation is less than 5 hours.
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