Solar Flares and Subsurface Vorticity

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Solar FlaresandSubsurface Vorticity

• R. Komm, F. Hill, R. Howe, R. Ferguson
• National Solar Observatory
• G. Barnes, K.D. Leka
• CoRA, NorthWest Research Associates

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Overview

• Solar eruptive events flares and CMEs
• Twisted magnetic fields are responsible.

• Fields extend below surface.
• Helioseismology measures flows below active
  regions.
• Relation between flows, fields, and flares

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Helioseismology
uses acoustic waves that propagate throughout the
Sun to measure the internal structure and
dynamics.
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Ring-Diagram Analysis
Ring displacements horizontal flows
cadence of 1 min 1664 min 1 ring day 16o
patches 0-16 Mm depth
Left Full-disk Doppler images of the Sun Right
Power spectrum of acoustic waves
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Subsurface Weather
Complex Flow Pattern
Haber Hindman Toomre
April 2002
Global and local pattern at 0.99R
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Twisted Subsurface Flows
Kinetic Helicity Density
AR 10486
Vorticity curl v kinetic helicity density v
curl v
Is this a proxy for twisted flux tubes?
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Discriminant Analysis
Goal To maximize the rate of correct
classifications
Diamonds 177 flaring active regions Crosses 846
non-flaring regions
DA parameters unsigned magnetic flux and
vorticity at 11 Mm
GONG Dopplergrams NSO/SOLIS magnetograms GOES
M-class flare data
Ferguson et al (2008)
Active regions above (and to the right of) the
DA line are predicted to flare.
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Discriminant Analysis
Heidke Skill Score Improvement over a no-event
prediction
Vorticity total flux Vorticity maximum
flux Vorticity
GONG Dopplergrams NSO/SOLIS magnetograms GOES
M-class flare data
Total flux Maximum flux
7 Mm 1 solar radius
Vorticity values at depths below 8 Mm lead to
higher skill scores.
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Summary (almost)

• The synoptic results are encouraging.
• What about daily variations?

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Temporal Variation
60 flaring active regions
53 flare-prolific regions
day 1 day 2 day 3 day4 day 5
day 6 day 7
day 1 day 2 day 3 day4 day 5
day 6 day 7
GONG Dopplergrams MDI/SOHO magnetograms GOES
flare data
magnetic flux enstrophy (13 Mm) total flare
intensity
15o 1 day
Decreasing magnetic flux
enstrophy vorticity squared
Big twisted active regions are flare-prolific.
Different flare and vorticity at similar flux
values.
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Summary

• Subsurface vorticity provides information about
  flaring active regions.
• We study evolution of active regions below the
  solar surface.
• What next developing this into a space weather
  resource.
• Input/advice encouraged.