First physics-based method for predicting large solar flares

Date:
August 21, 2020
Source:
Nagoya University
Summary:
A research team recently succeeded in developing the first
physics-based model that can accurately predict imminent large
solar flares, which can cause severe space weather disturbances
affecting Earth.



FULL STORY ========================================================================== Solar flares emit sudden, strong bursts of electromagnetic radiation
from the Sun's surface and its atmosphere, and eject plasma and energetic particles into inter-planetary space. Since large solar flares can cause
severe space weather disturbances affecting Earth, to mitigate their
impact their occurrence needs to be predicted. However, as the onset
mechanism of solar flares is unclear, most flare prediction methods so
far have relied on empirical methods.


==========================================================================
The research team led by Professor Kanya Kusano (Director of the
Institute for Space-Earth Environmental Research, Nagoya University)
recently succeeded in developing the first physics-based model that can accurately predict imminent large solar flares. The work was published
in the journal Science on July 31, 2020.

The new method of flare prediction, called the kappa scheme, is based on
the theory of "double-arc instability," that is a magnetohydrodynamic
(MHD) instability triggered by magnetic reconnection. The researchers
assumed that a small-scale reconnection of magnetic field lines can form
a double-arc (m- shape) magnetic field and trigger the onset of a solar
flare. The kappa -scheme can predict how a small magnetic reconnection
triggers a large flare and how a large solar flare can occur.

The predictive model was tested on about 200 active regions during solar
cycle 24 from 2008 to 2019 using data obtained by NASA's Solar Dynamics Observatory (SDO) satellite. It was demonstrated that with few exceptions,
the kappa-scheme predicts most imminent solar flares, as well as the
precise location they will emerge from. The researchers also discovered
that a new parameter -- the "magnetic twist flux density" close to a
magnetic polarity inversion line on the solar surface -- determines when
and where solar flares probably occur and how large they are likely to be.

Previous flare prediction methods have relied on empirical relations
in which the predictions of the previous day tend to continue into the
next day even if flare activity changes. In contrast, the kappa-scheme
predicts large solar flares through a physics-based approach regardless
of previous flare activity.

While it takes a lot more work to implement the scheme in real-time
operational forecasting, this study shows that the physics-based approach
may open a new direction for flare prediction research.


========================================================================== Story Source: Materials provided by Nagoya_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Kanya Kusano, Tomoya Iju, Yumi Bamba, Satoshi Inoue. A physics-based
method that can predict imminent large solar flares. Science,
2020; 369 (6503): 587 DOI: 10.1126/science.aaz2511 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200821094832.htm

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