Transcript Solar Sources of Geomagnetic Activity

Solar Sources of Geoeffective
Disturbances
N. Gopalswamy
NASA/GSFC
Greenbelt, MD 20771
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Geoeffectiveness
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Ability to significantly disturb geospace
Dst < -50
SEP Ip > 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
2004 September 11
CAWSES Theme 2 Meeting, Beijing
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)
2004 September 11
CAWSES Theme 2 Meeting, Beijing
What In situ Observations tell us?
• CMEs bring strong
magnetic fields
• Number of MCs ~
number of storms with
Dst < -100 nT
• All IP shocks are CMEdriven (ESP, SSC)
• Earth in CME related
flows for about a third of
the time during solar max
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Gopalswamy et al., 2004
Adv. Space Res.
TRANSIENT Flows at Earth
1 Shock only
2 shock + sheath
3 shock+Sheath+MC
4 MC Only
(slow)
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)
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Solar Wind Magnetic Field
% OCCURRENCE
Luhmann et al. 1999 (schematic)
0
5
20
B nT
40
Wind Mag Clouds
1996-2003
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1997 02 07 CME
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
Shock+ICME
Interacting with
Preceding CMEs
2004 September 11
Manoharan et al. 2004 JGR
CAWSES Theme 2 Meeting, Beijing
CMEs REACHING THE HELIOSPHERE
July 10 2000 – February 5, 2001 (7 months); Ulysses poleward of S60
Ulysses
LASCO HL LASCO LL
1 AU
8
101
25
602
8%
4% (8%)
w/o Backsided
CMEs
~ 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
2004 September 11
CAWSES Theme 2 Meeting, Beijing
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
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Halos are similar to other
CMEs:Wait for STEREO
2004 September 11
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Halo CMEs
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Full halos (F)
Asymmetric Halo (A)
Partial halo (P)
The faint extension
on the opposite limb
may be the CMEdriven shock
CAWSES Theme 2 Meeting, Beijing
Halo CMEs
are Faster on
the Average
• Halo CMEs have an
average speed of
1000 km/s
• Likely to be
geoeffective if Earthdirected and posses
southward B
• Likely to accelerate
SEPs by driving
shocks
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Fast and wide…
(47 deg non-halo)
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Metric Type II
IP Type II
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Speed, Width & Acceleration of DH CMEs
<V> = 1122 km/s
<W> = 104 deg
<a> = -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 )
2004 September 11
CAWSES Theme 2 Meeting, Beijing
CME Mass is also much higher
<M>1.6x1016
5.0x1015
<M> ~ 1.5x1015 g for all CMEs
(Vourlidas 2004)
2004 September 11
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1.5x1016
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
2004 September 11
CAWSES Theme 2 Meeting, Beijing
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)
2004 September 11
CAWSES Theme 2 Meeting, Beijing
Working Group: Solar Sources of
Geomagnetic Activity
Main Topics
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
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
The Project Team
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
2004 September 11
CAWSES Theme 2 Meeting, Beijing
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)
….
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?
2004 September 11
CAWSES Theme 2 Meeting, Beijing