The Active Region Evolution and Activity of Halloween 2003

1
The Active Region Evolution and Activity of
Halloween 2003

• Peter T. Gallagher (L-3 Com GSI)
• and
• R. T. James McAteer (NRC)
• at
• NASA Goddard Space Flight Center

2
18 Oct - 4 Nov, 2003 Activity Overview

• In 17 days there were
• 3 of the largest regions of cycle 23.
• One of the largest regions in recorded history.
• 3 ?-ray line flares observed by RHESSI.
• 12 X-class flares.
• X28, X17.2, and an X10.
• 41 M-class flares.
• 62 C-class flares.
• At least 15 halo CMEs.
• 5 days of enhanced gt100 MeV protons.

X17.2
X10.0
X8.3
3
NOAA 10484 Summary

• Dates observed 18 - 29 Oct (11 days)
• Maximum area 1940 ?h at W01 (23 Oct)
• Hale/Mount Wilson Class ???
• McIntosh Class Ekc
• Maximum number of spots 53
• Flare numbers 30 C-class, 14 M-class, 2 X-class
• Flare rates (flares/day) 2.73 (C-class), 1.27
  (M-class), 0.18 (X-class)

4
NOAA 10486 Summary

• Dates observed 23 Oct - 4 Nov (12 days)
• Maximum area 2680 ?h at W25 (30 Oct)
• Hale/Mount Wilson Class ???
• McIntosh Class Fkc
• Maximum number of spots 94
• Flare numbers 15 C-class, 20 M-class, 8 X-class
• and 3 ?-ray
• Flare rates (flares/day) 1.25 (C-class), 1.66
  (M-class), 0.66 (X-class)

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NOAA 10488 Summary

• Dates observed 26 Oct - 4 Nov (9 days)
• Maximum area 1830 ?h at W30 (30 Oct)
• Hale/Mount Wilson Class ???
• McIntosh Class Fkc
• Maximum number of spots 61
• Flare numbers 17 C-class, 7 M-class, 2 X-class
• Flare rates (flares/day) 1.88 (C-class), 0.77
  (M-class), 0.22 (X-class)

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The Active Regions of Oct-Nov 2003
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GOES X-rays

• Notable Events
• 18 Oct - 4 Nov
• X17.2 (28 Oct)
• X10.0 (29 Oct)
• X8.3 (2 Nov)
• X28 (4 Nov)

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GOES Protons

• First gt100 MeV increase from X1.2 on Oct 26 (NOAA
  10484 at W38).
• All gt100 MeV increase from regions with
• E08 lt Lon lt W90.
• 4 proton events from NOAA 10486 at
• E08 (X17.2 28 Oct)
• W02 (X10.0 29 Oct)
• W56 (X8.3 2 Nov)
• W90 (X28 4 Nov).

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The X-rated Details
W70 lt Lon lt W90
E08 lt Lon lt W70
E90 lt Lon lt E08

• From http//beauty.nascom.nasa.gov/ptg/oct-nov-20
  03-xflares.html

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Sun-Earth Connectivity

• Assume Parker spiral of form

• See a space weather report for Mars at
  http//beauty.nascom.nasa.gov/ptg/mars

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NOAA 10484

• X1.1 (19 Oct) / X1.2 (26 Oct)

12
NOAA 10486

• X17.2 (28 Oct) / X10.0 (29 Oct) / X8.3 (2 Nov) /
  X28 (4 Nov)

• X17.2 (28 Oct) / X10.0 (29 Oct) / X8.3 (2 Nov) /
  X28 (4 Nov)

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NOAA 10488

• X3.7 and X2.9 (3 Nov)

14
RHESSI Flare Locations NOAA 0484
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RHEESI Flare Locations NOAA 0486
16
RHESSI Flare Locations NOAA 0488
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Magnetic Flux Changes

• NOAA 10484
• B decays slowly.
• B- increases then decays.
• NOAA 10486
• Growth in B until central meridian, then decay.
• Growth in B- until central meridian, then remains
  constant.
• B- shows rapid change during X17.2.
• NOAA 10488
• Rapid growth in B and B- over 2-days.

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Polarity Balance

• NOAA 10484
• B- gt B
• B const
• dB-/dt gt 0
• NOAA 10486
• B gt B- then B lt B-
• dB-/dt gt 0
• NOAA 10488
• B gt B-
• dB/dt gt dB-/dt

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Horizontal Gradient

• Converging photospheric flows sweep opposite
  polarity fields towards the neutral line of the ?
  (bipolar groups do NOT form significant neutral
  lines, transverse gradients, and hence flares).
• Large transverse gradients in the photospheric
  magnetic field are observed across the neutral
  line of large ? spots (Patty Hagyard, 1986
  Zhang et al., 1994).
• Over a period of hours, the continued
  concentration of opposite polarities in a
  relatively small area leads to strong transverse
  gradients (Gallagher, Moon, Wang 2002).
• ?energy_buldup (hrs - days) gtgt ?energy_resease
  (secs - mins)
• An instability in the corona results in the
  release of stored (Priest Forbes Antiochos et
  al.)

20
NOAA 10484

• Automated neutral line and gradient measurements.
• Large field gradients observed across multiple
  neutral lines.
• X1.1 (19 Oct)
• X1.2 (26 Oct)

21
NOAA 10486

• Strong transverse gradients in Blos.
• Multiple long and complex neutral lines.
• X17.2 (28 Oct)
• X10.0 (29 Oct)
• X8.3 (2 Nov)

22
NOAA 10488

• Short neutral lines.
• Strong gradients.
• X2.7 (3 Nov).
• X3.9 (3 Nov).

23
Size Distribution of Sunspot Groups (1900-2000)

• Maximum areas
• NOAA 10484 1940 ?h
• NOAA 10486 2680 ?h
• NOAA 10488 1830 ?h

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Size Distribution of Sunspot Groups (1874-2003)

• NOAA 10486 in largest 5 of regions
• NOAA 10484 and 10488 in largest 24 of regions

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Area, Class and Activity

• Sammis et al., ApJ, 540, 583, (2000)
• 2789 active regions (1989-1997)
• All flares above X4 come from 11 ??? regions with
  areas gt1000 ?h.

X
M
C
B
26

• SOHO EIT 19.5 nm (18 Oct - 5 Nov)

27
Summary

• All three regions were large (ie, gt1500 ?h),
  multipolar (ie, magnetically complex), highly
  dynamic (ie, changing flux distribution), with
  strong gradients (ie, gt 50 G/Mm) and long neutral
  lines (ie, gt60 Mm) magnetic properties essential
  to flare and CME production.
• NOAA 10486 was particularly unusual in terms of
  its size, complexity, and activity. One of the
  largest and most active regions in the past
  100-years.
• Does the formation of these region at such a late
  stage in the solar cycle provides evidence for
  nonlinear dynamo action?
• Does the emergence of several regions imply the
  regions resulted from global rather than local
  effects?
• Much work still to be done to understand the
  relationship between the field configuration in
  the photosphere with the activity observed in the
  corona.