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Coronal Ejecta in October - November of 2003 and predictions of the
associated geomagnetic events
Vasyl Yurchyshyn
Qiang Hu
1Big
Bear Solar Observatory, New Jersey Institute of Technology, http://www.bbso.njit.edu/~vayur
of Geophysics and Planetary Physics, University of California, Riverside, http://www.igpp.ucr.edu
2Institute
We have found recently that the intensity of Bz in the IMF is correlated with the plane of sky speed of coronal mass ejections (CMEs)1,2 . In turn, the Bz in the IMF is correlated with
the Dst index of geomagnetic activity2,3,4,5.
Here we present results of prediction of the magnitude and the orientation of the Bz and the Dst index made for 3 halo CMEs erupted on October 28 (event I), October 29 (event
II) and November 18 (event III) of 2003. The comparison between the predicted values and the observed data shows that we were able to successfully predict the magnitude of 2
out of 3 geomagnetic events (events I and II), while we have underestimated the magnitude of the Dst index for the event III on November 18 2003.
Prediction
Scheme:
I. The
magnitude of the Bz in IMF is
related to the plane of sky
speed of a halo CME:
Event II:
Event III:
The X17.2/4B flare started at 0951UT on Oct 28 2003 and it
was associated with a halo CME. The clock angle (measured
clockwise from the east) of the post flare loops system,
associated with this CME, was about 215 deg and the erupted
field had negative helicity . This suggests that the axial field
of the CME may have a southward Bz component. The plane
of sky speed of the CME was about 1500km/s. Based on this
speed we predicted i) the magnitude of the Bz in IMF to be 30 … -44 nT and ii) the decrease in the Dst index from the
base value be –250…-320 nT (the blue box below).
The X11 flare at 2037UT on Oct 29 2003 produced another
halo CME. The lack of the data on the day of the eruption did
not allow us to reliably determine a possible orientation of
the axial field and magnetic helicity. However, available data
seemed to suggest that the associated interplanetary ejecta
may have negative helicity. The plane of sky speed of this
CME was, too, about 1500km/s. Based on this speed we
predicted i) the Bz to be between –30 and -44 nT and ii) the
magnitude of the decrease in the Dst index from its base
value to be –250 … -320 nT (see the blue box).
The M3.9/2N flare at 0812UT on Nov 18 2003 produced a fast
halo CME (1400km/s). Although the axial field of the postflare loops system (PFL) was east-west oriented and the
system had positive helicity, the flare ribbons stretched along
the dark H filament, which suggests that the orientation of
the ejecta may not coincide with the that inferred from the
PFL. The clock angle of the PFL was about 10 deg. Based on
the CME speed we estimated that i) the Bz to be between –21
and -35 nT and ii) the magnitude of the decrease in the Dst
index from its base value to be -190…-250 nT (the blue box).
Bz in the IMF at 1AU, nT
Yurchyshyn et al. 2003, Adv. Space Res. 32, #10
Yurchyshyn et al. 2004, Space Weather, 2, S02001
Event I:
Oct 28 CME
Event I
Oct 30 ACE
event iI
Oct 29 ACE
event I
Solid line is an exponential fit
Bz[nT]=12.3+0.7exp(V/404). (r.m.s=7nT)
Plane of sky speed of halo CMEs, km/s
Prediction Scheme: II. In turn,
the Dst index of geomagnetic
activity can be estimated
from the Bz component:
Nov 18 CME
Event III
Oct 29 CME
Event II
The interplanetary ejecta arrived
at 1 AU on Oct 30 at about 1530UT.
Since we could not clearly
distinguish a magnetic cloud in this
disturbance - no magnetic cloud
reconstruction has been done.
The magnetic cloud arrived at
1AU at about 1200UT. It was
southwardly
oriented,
as
expected, with the clock angle
of about 266 degree and it had
negative helicity (see the event
reconstruction figure below) .
Nevertheless this, quite possibly,
complex ejecta, indeed, presented
a strong southward Bz component
of -29 nT and the Dst index
dropped by about -300 nT from
The Bz measured by the ACE
satellite reached -26 nT, while
the Dst index decreased by 310 nT from –50 to -360 nT.
-100 to -400 nT.
Event I: Oct 29 ACE Reconstruction
Event II: Oct 29 2003 X11/2B Flare
The magnetic cloud arrived at
1AU at about 0600UT on Nov
20 and it was southwardly
oriented with the clock angle
of about 311 degree and
positive helicity (see figure
below) .
However, the Bz, measured by
the ACE satellite, reached -52
nT, while the Dst index
decreased by -310 nT from -50
to -360 nT.
Event III: Nov 20 ACE Reconstruction
Ejecta Time: 10/29 1117 UT
– 10/30 0349 UT
Ejecta Time: 11/20 0936 UT
– 11/20 1912 UT
Cone angle: 113 deg
Cone angle: 105 deg
Clock angle: 266 deg
Clock angle: 311 deg
(clockwise from positive Y)
(clockwise from positive Y)
Axial Field: Bz0= 45 nT
GSE Z
Results of the Prediction Made
for 3 halo CMEs in October –
November 2003:
prediction
Clock angle
Event I: Oct 28 2003 X17.2/4B Flare
contours show position of the H flare and lines are linear force free field
EIT 195 A at 1313UT + LFFF a=-0.008
The blue arrow indicates
the direction of the axial
field in the post flare
arcade.
Oct 28, 2003 CME; Event I
Oct 29, 2003 CME; Event II
Bz in the IMF at 1AU, nT
Magnetic Helicity: Positive
GSE Z
GSE Y
Orientation of the Ejecta was 266 deg
measurement
Nov 18, 2003 CME; Event III
This arcade was associated
with the halo CME on Oct
28 and its magnetic field
had negative helicity.
Oct 28 Halo CME was earth directed
and, as suggested by the ACE data, it
was approximately oriented along
the NS line
Plane of sky speed of halo CMEs, km/s
Axial Field: Bz0= 57 nT
There is no Ha data available for this
solar event. Nevertheless, data from
the Global Ha Network obtained 10
hours before the eruption as well as
the data on the previous days seem
to suggest that the erupted field
may have its leading magnetic field
directed southward.
Magnetic Helicity: Negative
GSE Y
The clock angle of this
EIT 195 A at 1313UT + LFFF a=-0.008
arcade was about 215
degree, which is very
close to the clock angle of
the reconstructed
magnetic cloud (266 deg).
BBSO DMG at 1716UT + LFFF (
 =-0.008)
Nov 20 ACE
event III
Clock angle
Orientation of the Ejecta was 311 deg
References:
1. Yurchyshyn, V., Wang, H., and Abramenko, V., 2003, Adv.
Space Res., 32, #10
2. Yurchyshyn, V., Wang, H., and Abramenko, V., 2004, Space
Weather, 2, S02001
3. Cane, H.V., Richardson, I.G., and St. Cyr, O.C., 2000, GRL, 27
4. Wu, C.C., and Lepping, R.P., 2002, JGR, 107, #A11
5. Gonzalez, W.D., et al., 2004, J. Atm. Sol-Terr. Phys., 66, 161
http://www.bbso.njit.edu/~vayur/g_storms.html
Acknowledgement: We thank the ACE MAG/SWEPAM instrument team and the ACE Science Center for
providing the ACE data. In particular, we thank Ruth Skoug for providing the merged data set for the Oct 30
event. We acknowledge the use of geomagnetic data from the World Data Center for Geomagnetism in Kyoto.
The CME catalog is generated, and maintained, by the Center for Solar Physics and Space Weather, The
Catholic University of America in cooperation with the Naval Research Laboratory and NASA. SOHO is a
project of international cooperation between ESA and NASA. We acknowledge the use of the data from the
Global High Resolution Ha Network, operated by the Big Bear Solar Observatory, New Jersey Institute of
Technology. The BBSO work was supported, in part, by NSF grants ATM-9903515, ATM-0205157, ATM-0076602
and NASA(NAG5-9682) grants; work at UCR was funded by NASA NNG04GF47G grant .
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the National Science Foundation.
Event III: Nov 18 2003 M3.9/2N Flare
Kanzelhohe Ha at 0818UT:
Note Ha ribbons (contours)
running along the dark right
handed (positive helicity)
filament
Kanzelhohe Ha+0.44A at
0814UT: Yellow dots show the
position of the same erupted
EIT filament, while the red
arrow show the orientation of
the interplanetary ejecta.
EIT 195A at 0713UT: Dots
trace a dark EIT filament which
eruption was associated with
the flare, blue dots show
location of its footpoints
BBSO DMG at 2015UT: blue
lines are a LFFF (=0.002) and
the blue arrow shows the
direction of the axial field in
the post flare loop system
In this unique case we were able
to identify the footpoints of the
erupted magnetic structure. The
comparison of the erupted EIT
and H  filaments with the data
on the magnetic cloud
reconstruction shows that their
orientation is very similar.
However, unlike event I, the
orientation of the post flare loop
system (the clock angle was
about 10 degree) significantly
differs from the orientation of
the magnetic cloud.