Transcript A Catalog of Halo Coronal Mass Ejections from SOHO N. Gopalswamy1, S.

A Catalog of Halo Coronal
Mass Ejections from SOHO
N. Gopalswamy1, S. Yashiro2, G. Michalek3, H. Xie3, G.
Stenborg2, A. Vourlidas4, R. A. Howard4
1NASA
Goddard Space Flight Center
2Interferometrics 3Catholic University
4Naval Research Laboratory
Plan of the Talk
•
•
•
•
•
•
•
CDAW Data Center
What are Halo CMEs?
Why Catalog Halo CMEs?
A Brief Description of the Catalog
Geoeffectiveness of Halos
Solar Energetic Particles and Halo CMEs
Summary
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
2
CDAW Data Center
• The CDAW Data Center (http://cdaw.gsfc.nasa.gov)
is a repository of coronal mass ejection (CME) data
sets useful to the Heliophysics community
• Contains value-added data products on CMEs
detected by SOHO/LASCO.
• The SOHO/LASCO CME catalog is linked to the
Virtual Solar Observatory (VSO).
• The Halo CME Catalog is a new data product
focusing specifically on halo CMEs known to have
significant impact on Heliospace including Space
Weather.
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
3
What are Halo Coronal Mass
Ejections?
• CMEs that appear to surround the occulting disk in sky-plane
projection (Howard et al. 1982)
• Halos are no different from other CMEs, except that they must be
faster and wider on the average to be visible outside the occulting
disk
• Halos affect a large volume of the corona
• Most of the halos may be shock-driving
• Most halos are geoeffective (70%)
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
4
Halos: Similar to other CMEs,
but selected by occulting disk
Halo CME when AR on disk
Normal CME when viewed sideways
2500 km/s
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
2700 km/s
5
Halo CMEs
Front-side halo
Partial halo becomes asymmetric halo UN/ESA/NASA/JAXA Workshop
back-side halo
6
Halo CMEs
Two halo CMEs headed earthwards
SEPs acceleration starts when the
CME is close to the Sun (a few Rs)
SEPs reach SOHO (located along the
SUN-Earth line at L1) in 10s of minutes
SOHO detectors blinded by SEPs
SOHO’s performance in imaging the corona
is temporarily affected
--Sometimes fatal
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
7
All CMEs (1996-2006)
1052 km/s
Wide
11.5%
Halos
3.5%
Halo CMEs are faster on the average and wider
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
8
Halo CME Properties
Halo CMEs, discovered in Solwind
data (Howard et al. 1982; 1985), have been
recognized in the SOHO era as an important
subset relevant for space weather
Only ~3.5% of all CMEs are halos
Halos are ~ 2 times faster than the
average CME.
Flares associated with halo CMEs are
also an order of magnitude more intense
than the average soft X-ray flare
The high kinetic energy of the halos allows
them to travel far into the interplanetary
medium and impact on Earth
causing geomagnetic storms.
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
9
Why Catalog Halo CMEs?
• Most of the halos may be shock-driving.
• 70% halos are geoeffective when frontsided
(Gopalswamy et al. 2007). Halo CMEs are the
main sources of severe space weather at Earth.
• They are important to study the solar
connection because most of the magnetic clouds
are due to Halo CMEs.
• Halo CMEs represent one of the most energetic
CME populations.
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
10
A Halo CME with SEP events & Shock at 1-AU
Shock
SEP
Solar Location
Halo CME
Type II Burst (DH –km)
shock
SSC
UN/ESA/NASA/JAXA Workshop
11
The Halo CME Catalog
URL: http://cdaw.gsfc.nasa.gov/CME_list/HALO/halo.html
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
12
Java Movie Frame
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
13
Javascript Movies Available for
Analysis
Movie Name Explanation
c2_rdif.html
c2eit.html
c2eit_gxray.html
c2eit_gxray4laptop.html
c2eit_waves.html
c2eit_waves4laptop.html
c2rdif_gxray.html
c2rdif_gxray4laptop.html
c2rdif_waves.html
c2rdif_waves4laptop.html
c3_rdif.html
c3rdif_gxray.html
c3rdif_gxray4laptop.html
c3rdif_waves.html
c3rdif_waves4laptop.html
images/
2008 June 2-6
Gopalswamy
Difference movie with C2 and EIT images overlaid
Direct movie with C2 and EIT images overlaid
Direct C2+EIT movie with GOES soft X-ray light curve
Same as above with GOES light curve modified to fit laptop screen
Direct C2+EIT movie with Wind/WAVES dynamic spectrum
Same as above with dynamic spectrum modified to fit laptop screen
Difference C2+EIT movie with GOES soft X-ray light curve
Same as above with GOES light curve modified to fit laptop screen
Difference C2+EIT movie with Wind/WAVES dynamic spectrum
Same as above with dynamic spectrum modified to fit laptop screen
Difference movie with C3 images
Difference C3 movie with GOES soft X-ray light curve
Same as above GOES light curve modified to fit laptop screen
Difference C3 movie with Wind/WAVES dynamic spectrum
Same as above with dynamic spectrum modified to fit laptop screen
All the images used in the above movies are in this directory
UN/ESA/NASA/JAXA Workshop
14
Geoeffectiveness of Halos
• The ability to produce significant
geomagnetic disturbances (e.g., Dst ≤ - 50
nT)
• Front-sided halos originate close to disk
center of the Sun, so they are likely to hit
Earth
• Off-centered halos produce moderate
storms
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
15
CMEs and Geomagnetic Storms
CME on the
backside of
the Sun.
The CME
does not
reach Earth
No storm
CME heading
Towards Earth
Hits Earth
Causes big storm
(Dst -260 nT)
2008 June 2-6
Gopalswamy
CME moves west
glancing blow causes
UN/ESA/NASA/JAXA Workshop
moderate storm
16
Geoeffectiveness of Disk and Limb Halos
75%
60%
• Frontside Halos are highly geoeffective (average Dst = -117 nT)
• Frontside Off-Limb halos (Flimb) are moderately geoeffective (average = -72 nT)
• Backside halos (including near the limb) are not geoeffective (average = -43 nT)
• Knowing the source location of the halo CMEs is important
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
17
Where do Halos originate from?
RISE
MAX
DECL
Halo sources are within 30 deg lat  Mostly from Active regions
Slightly higher latitudes during solar minimum: effect of solar global field in polar
coronal holes in pushing CMEs to the equatorial plane
Closest to the equator during the declining phase (butterfly pattern)
Non-geoeffective halos also originate close to the disk center  additional factors that
decide geoeffectiveness
18
Coronal Hole Effects on CMEs
Disk-center CME, but no ICME (only shock)
CME is deflected away from the Sun Earth line
Disk-center CME resulting in ICME + shock
19
CME is deflected towards the Sun Earth line
Speed & Location
Halo CME speed vs. longitude.
Non-geoeffective halos slower,
and originate farther from the disk center.
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
20
CMEs of Cycle 23
Gopalswamy, 2006
CME speed < ~4000 km/s  Limit to the
Free energy available in active regions
CME population
<V> km/s
All CMEs
471
metric II CMEs
610
MC CMEs
774
Geoeffective CMEs
1042
Halo CMEs
1052
mkm II CMEs
1500
SEP CMEs
1600
GLE CMEs
2000
11% of CMEs are wide (W ≥120o) ~1000
Fast and wide CMEs ~500
Halo CMEs ~500 (some are slower than 900 km/s
MCs ~100; intense storms ~100; SEPs ~100
Sources of geoeffective &
SEPeffective CMEs
Ip < 50 pfu
SEP
Eastern 33%
N
E
Western 67%
W
Dst > -200 nT
Ip  50 pfu
SEP sources
- 300nT < Dst < - 200 nT
S
Dst < -300 nT
Magnetic-storms sources
Disk center (W15) source for plasma impact; western CMEs for SEPs
Summary of the Catalog
• The Halo CME Catalog contains all the Halo CMEs
identified in the SOHO/LASCO Data (1996- to date).
• Most information available in the general CME catalog
is also available for halo CMEs.
• In addition, heliographic coordinates of the source
from which the Halo CMEs erupt, the soft X-ray flare
importance, and the flare onset time are included.
• In the near future, deprojected speeds will be included.
• This catalog is useful to the LWS and Space Weather
communities; Will be accessible from VSO site.
• URL:
http://cdaw.gsfc.nasa.gov/CME_list/HALO/halo.html
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
23
Science Conclusions
• Halos constitute ~3.6% of all CMEs (11% when partial
halos included).
• Halo CMEs, as a class, are more energetic are and
associated with bigger soft X-ray flares.
• Halos have a much higher rate during maximum phase
of the solar cycle
• Halos originate mostly in the active region belt
• There is a center-to-limb decline of geoeffectiveness:
about 75% of the disk halos and 60% of limb halos are
geoeffective.
• Geoeffectiveness also depends on the speed of the
CMEs
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
24
What is a CME?
A prominence eruption that becomes
CME core (in microwaves, Nobeyama)
Brightening on the disk is the associated flare
2008 June 2-6
Gopalswamy
SOHO/LASCO sees the CME
Later in the corona with the core
UN/ESA/NASA/JAXA Workshop
25
Consequences of CMEs
• Drive shocks (SEPs, ESPs, Radio bursts,
SSC, GLEs)
• (Ozone depletion, Cloud cover change)
• Induce Flares (SID, impulsive SEPs)
• Geomagnetic Storms: frontside halos
2008 June 2-6
Gopalswamy
UN/ESA/NASA/JAXA Workshop
26