Solar Sources of Geoeffective Disturbances

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Solar Sources of Geoeffective Disturbances

• N. Gopalswamy
• NASA/GSFC
• Greenbelt, MD 20771

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Geoeffectiveness

• Ability to significantly disturb geospace
• Dst lt -50
• SEP Ip gt 10 pfu in the 10 MeV channel
• Arrival of plasmas, particles and electromagnetic
  radiation decide the lead times available
• Narrow down the solar events for space weather
  forecast purposes

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Geoeffective Solar Events

• Coronal Mass Ejections (severe geomagnetic
  storms, SEP events) most unpredictable
• High-speed Streams (mild, but numerous
  geomagnetic storms)
• Flares (prompt effects such as SID)

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What In situ Observations tell us?

• CMEs bring strong magnetic fields
• Number of MCs number of storms with Dst lt -100
  nT
• All IP shocks are CME-driven (ESP, SSC)
• Earth in CME related flows for about a third of
  the time during solar max

Gopalswamy et al., 2004 Adv. Space Res.
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TRANSIENT Flows at Earth
1 Shock only
4 MC Only (slow)
2 shock sheath
3 shockSheathMC
Earth is embedded within one or the other of the
above CME-related flows for 35 Time during
solar maxima and 10 of the time during solar
minima (Cliver et al. 2003)
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Solar Wind Magnetic Field
1997 02 07 CME
Luhmann et al. 1999 (schematic)
OCCURRENCE
0
20
40
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B nT
Wind Mag Clouds 1996-2003
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Solar Sources of ICMEs
Close to Disk Center (30deg) Slight westward
bias (Wang et al Zhang et al)
Shock ICME
Sources of IP shocks
Only shock
ShockICME Interacting with Preceding CMEs
Manoharan et al. 2004 JGR
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CMEs REACHING THE HELIOSPHERE
July 10 2000 February 5, 2001 (7 months)
Ulysses poleward of S60
a tenth of the CMEs produced at the Sun seem to
reach far into the heliosphere These are the ones
that survive for long distances from the Sun
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Special Populations (1-2)

• Only a small fraction of all CMEs has
  significant influence on the heliosphere
• Halo CMEs responsible for large geomagnetic
  storms
• Fast and wide CMEs responsible for accelerating
  electrons (radio bursts) and SEPs
• Fast Wide Western CMEs produce high levels of
  SEP intensity at Earth

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Halos are similar to other CMEsWait for STEREO
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Halo CMEs

• Full halos (F)
• Asymmetric Halo (A)
• Partial halo (P)
• The faint extension on the opposite limb may be
  the CME-driven shock

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Halo CMEs are Faster on the Average

• Halo CMEs have an average speed of 1000 km/s
• Likely to be geoeffective if Earth-directed and
  posses southward B
• Likely to accelerate SEPs by driving shocks

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Fast and wide
(47 deg non-halo)
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Metric Type II
IP Type II
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Speed, Width Acceleration of DH CMEs
ltVgt 1122 km/s
ltWgt 104 deg
ltagt -6 m/s/s
- CMEs driving shocks in the near-Sun IP medium
are faster and wider than regular CMEs - Tend to
decelerate, probably due to coronal drag.
(Gopalswamy et al., 2001 JGR )
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CME Mass is also much higher
ltMgt1.6x1016
5.0x1015
ltMgt 1.5x1015 g for all CMEs (Vourlidas 2004)
1.5x1016
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DH type II, FWFW, SEPs

• Overall good correlation because of physical
  relation (CME?shock?particles)
• DH is largest in number (Eastern Events included)
• Minor differences due to other parameters like
  Alfven speed
• Too many flares

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Problem Areas

• Halo CMEs without Geomagnetic Storms (Proper
  characterization orientation of the magnetic
  field?)
• Fast and wide CMEs without particle acceleration
  (property of the ambient medium?) Use radio data
  (All large SEP events are associated with IP type
  II)

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Working Group Solar Sources of Geomagnetic
Activity
Main Topics 1. Solar sources
Coronal Mass Ejections, Coronal Holes,
Large-scale Magnetic structures and boundaries,
Polar magnetic fields 2. Structure of the
heliosphere and interplanetary transport of
solar eruptions 3. Solar energetic ions and
electrons 4. Geospace response to solar events

• Objectives
• To understand how solar events
• such as CMEs and high speed streams
• impact the geospace
• - investigation of the underlying science
• development of prediction/forecast
• models and necessary tools

The Project Team N. Gopalswamy (USA,
Chair) B. V. Jackson (USA) V. Obridko (Russia) A.
Prigancova (Slovakia) B. Schmieder (France) K.
Shibasaki (Japan) D. Webb (USA, IAU Rep. ) S. T.
Wu (USA) M. Kojima (Japan) M. Zhang (China) .
Meetings Preliminary meeting
in China (before IAU Symposium Sep11-12
2004) Large meeting in 2005 (during the SCOSTEP
Symposium)
WG formed during the ISCS meeting in Slovakia,
June 2003
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CAWSES Campaign(March 29-April 4, 2004)
Participants Solar SOHO/LASCO
(N. Gopalswamy) HeI 10830 (J. Burkepile) H-alpha
(B. Schmieder, Haimin Wang) ISOON (D.
Neidig) Microwave (Shibasaki) IPS (Manoharan,
Tokumaru) SXI (D. Biesecker) Metric (M.
Akioka)Decametric (M. Kaiser, N. Gopalswamy)
CME list (11 CMEs) Flares
http//cdaw.gsfc.nasa.gov/CAWSES What Next?