Comparative Study of Data-driven Solar Coronal Field Models Using a Flux Emergence Simulation as a Ground-truth Data Set. (arXiv:2001.03721v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Toriumi_S/0/1/0/all/0/1">Shin Toriumi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Takasao_S/0/1/0/all/0/1">Shinsuke Takasao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cheung_M/0/1/0/all/0/1">Mark C.M. Cheung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jiang_C/0/1/0/all/0/1">Chaowei Jiang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guo_Y/0/1/0/all/0/1">Yang Guo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayashi_K/0/1/0/all/0/1">Keiji Hayashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Inoue_S/0/1/0/all/0/1">Satoshi Inoue</a>
For a better understanding of magnetic field in the solar corona and dynamic
activities such as flares and coronal mass ejections, it is crucial to measure
the time-evolving coronal field and accurately estimate the magnetic energy.
Recently, a new modeling technique called the data-driven coronal field model,
in which the time evolution of magnetic field is driven by a sequence of
photospheric magnetic and velocity field maps, has been developed and revealed
the dynamics of flare-productive active regions. Here we report on the first
qualitative and quantitative assessment of different data-driven models using a
magnetic flux emergence simulation as a ground-truth (GT) data set. We compare
the GT field with those reconstructed from the GT photospheric field by four
data-driven algorithms. It is found that, at least, the flux rope structure is
reproduced in all coronal field models. Quantitatively, however, the results
show a certain degree of model dependence. In most cases, the magnetic energies
and relative magnetic helicity are comparable to or at most twice of the GT
values. The reproduced flux ropes have a sigmoidal shape (consistent with GT)
of various sizes, a vertically-standing magnetic torus, or a packed structure.
The observed discrepancies can be attributed to the highly non-force-free input
photospheric field, from which the coronal field is reconstructed, and to the
modeling constraints such as the treatment of background atmosphere, the bottom
boundary setting, and the spatial resolution.
For a better understanding of magnetic field in the solar corona and dynamic
activities such as flares and coronal mass ejections, it is crucial to measure
the time-evolving coronal field and accurately estimate the magnetic energy.
Recently, a new modeling technique called the data-driven coronal field model,
in which the time evolution of magnetic field is driven by a sequence of
photospheric magnetic and velocity field maps, has been developed and revealed
the dynamics of flare-productive active regions. Here we report on the first
qualitative and quantitative assessment of different data-driven models using a
magnetic flux emergence simulation as a ground-truth (GT) data set. We compare
the GT field with those reconstructed from the GT photospheric field by four
data-driven algorithms. It is found that, at least, the flux rope structure is
reproduced in all coronal field models. Quantitatively, however, the results
show a certain degree of model dependence. In most cases, the magnetic energies
and relative magnetic helicity are comparable to or at most twice of the GT
values. The reproduced flux ropes have a sigmoidal shape (consistent with GT)
of various sizes, a vertically-standing magnetic torus, or a packed structure.
The observed discrepancies can be attributed to the highly non-force-free input
photospheric field, from which the coronal field is reconstructed, and to the
modeling constraints such as the treatment of background atmosphere, the bottom
boundary setting, and the spatial resolution.
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