Relationship Between Magnetic Clouds and Earth-Directed CMEs: Space Weather Research in Stanford Solar Group

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Relationship Between Magnetic Clouds and
Earth-Directed CMEsSpace Weather Research in
Stanford Solar Group

• Xuepu Zhao
• The Second International Space Weather Symposium
• Nanjing, Oct. 17-21, 2009

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1. Introduction

• Stanford solar group is a member of LWS CISM,
  and involved in Space Weather research in four
  aspects
• (a) Provide WSO, MDI, and the coming-up
  HMI synoptic maps synchronic frames to coronal
  models as coronal boundary condition for
  predicting the corona ambient solar wind
  Hoeksema et al, 2008 Yang et al, 2008 Zhao et
  al, 1997 2009
• (b) Provide high-cadence MDI and HMI
  (vect) magnetogrm. for study of active regions
  activity index Yang et al. 2007
• (c) Provide ZEC cone model parameters to
  heliospheric models to launch plasma clouds and
  to predict the arrive time of shocks and ICMEs
  Zhao et al, 2002 2005 2008 Hayashi et al,
  2006.

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• (d) Develop improve algorithm for predicting
  storm intensities.
• According to Siscoe Schwenn review
  report Space Sci. Rev., 123 453, 2006 the only
  existing algorithm for forecasting intensities
  caused by ICME bodies is based on our early work
  (Zhao Hoeksema, 1997), i.e.,
• D(h) (11.49 0.12 Le) 4.70
  (1)
• Bg(?)(nT) (10.76 0.10 Le) 5.12
  (2)
• Le(deg) (-1.4 0.7 Fo) 17.8
  (3)
• Here D-Bs duration, B-Bs intensity, Le-MC
  latitude, Fo-DSF latitude.
• Fig. 1 shows how Bs events i.e., the long
  (gt 10 hrs) interval of strong (lt -10 nT)
  southward IMF component depend on the MCs
  central axial field direction.
• We review here our efforts to improve Eqs. (1),
  (2) and especially (3) by investigate the
  relationship of the orientation between MCs and
  E-D CMEs.

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• Figure 1. There is no
• Bs events when MCs
• point to northward.
• The duration and
• intensity of Bs events
• strongly depend on
• the MCs central axial
• direction.

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2. Improving the prediction of Bs events
Multiple regression

• The Eqs (1) (2) have not included the effect of
  CME velocity, they are valid only for slow CMEs
  Schwenn, 2005. As shown in Figs. 2, the radial
  CME velocity can be well predicted using the code
  of MASENLILWSAZEC.
• We have developed a multiple regression Zhao
  Hoeksema, 2006, as shown in Fig. 3, to include
  the effect of CME velocity, and the effect of
  rope central axial field strength (when it is
  available).

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Fig. 2. Predicted and observed ICME associated
with the 19970512 (left column, Odstrcil,
Riley, Zhao, 2004 ) and 20061213 (right column,
Owen , Zhao, 2008) E-D halo CME. The CME
propagation speed arrival time can be well
predicted.
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Fig. 3 Multiple regressions for the duration, T,
and intensity, I, of Bs events are shown at the
top of each panel. Symbols La, U, and Ba in the
expressions denote, respectively, the ecliptic
latitude of central axis, speed, and central
axial field strength of MCs. The symbols and
denote the observed and predicted duration and
intensity of Bs events Zhao Hoeksema, 2006.
Correlation coefficients for intensity (coe in
panels) increase from 0.69 to 0.82, 0.87.
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3. Improving the prediction of the central axial
field direction of MCs

• Bs events have one-to-one correspondence with
  storms Tsurutani et al, 1988. The central
  axial field direction, CAD, of MCs determines the
  strength and duration of most of Bs events Zhao
  Hoeksema, 1998. Thus, prediction of the CAD of
  MCs is one of key issues in the space weather.
  However, there is no space observations of Ha
  filaments!
• Well show how to use heliospheric current sheet
  (HCS), EIT Post eruption Arcade (EPA), and E-D
  halo CMEs to predict MCs orientation.

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3a
3.1 MCs and local HCS
3b
3c
Fig. 3. (a) The Magnetic cloud is a segment of
huge interplanetary magnetic flux ropes. (b)
HCS is the conduit for the CME propagation
Crooker et al, 1993 Zhao Hoeksema, 1996.
(c) The north-south hemispheric rule of the
handedness of the magnetic helicity.
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Fig. 4a. Local inclination of HCS near the
source region of E-D halo CMEs. Symbols and
denote CME source solar disk center at CME
onset. Dark lines denote HCSs, blue and red the
outward and inward field polarity. Near minimum
phase, MCs orientated horizontally because HCS is
nearly parallel to the solar equator.
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Fig. 4b Determination of the central axial
direction of MCs on the basis of the
local inclination of HCSs and N-S asymmetry of
the handedness of helicity Zhao and
Hoeksema, 2007.
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Fig. 4c Among 35 E-D CMEs, there are 7 partially
northward, consistent with that 7 E-D CMEs have
no storm associated, indicating that the local
inclination of HCSs is a good predictor of MCs
orienta. (Zhao 7 Webb, 2003)
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Fig. 5 The further confirmation of the
correlation of the orientations between MCs and
the local inclination of HCS. Adopted from
Yurchyshyn , 2008.
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3.2. MCs EPAs Fig. 6 Oct. 29 and 31, 2003
MCs S1 ICME1 28 Oct 2003 halo CME N ? S,
left-handed MC (Hu et al, 2005) with low proton
density not-low temperature. S2 ICME2 29
Oct 2003 halo CME. There is no southward HMF
component. (Adopted from Farrugia et al., 2005.)
The two MCs are not originated in closed
regions underlying HCS.
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Fig. 7 The 29 31 Oct. 2003 MCs and WSO CR2009
HCS . The symbols around Carrington longitudes
of 303 and 275 degs denote Oct 28 X17 flare
CME and Oct 29 X10 Flare CME. They are not
underlying HCS.
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BCR
UCR
UCR
UCR
Fig. 8 The unipolar and bipolar coronal closed
field regions, UCR BCR. Only BCRs are located
underneath the HCS. Zhao and Webb, 2003.
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Fig.9 Calculated magnetic arcades anchored all
pixes with different top ranges. AR0486 is
located in a UCR The Highest arcade top is 1.10
Rs
0486
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EIT 195 2003.10.28_13.13 (11.00)
Fig. 10. The locus of arcade tops above the X17
flare is parallel to the
left-handed EIT bright structure, predicting a MC
with a leading northward HMF
component, consistent with ACE obs.
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EIT 195 2003.10.29_22.00 (20.37)
Fig. 11 The locus of arcade tops above the X10
flare is parallel to the EIT left- handed arcade,
predicting a MC with a northward HMF component,
consistent with ACE observation.
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Fig. 12 Kink instability. Adopted from Y. Fan,
2007. Question of hemispheric role of handedness
possible answer.
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4. Summary

• 4.1 We have tried to improve the prediction of
  arrival time of shocks and ICMEs using
  ENLILWSAEZC. The next step is to find a way to
  rather objectively determine the outline of
  observed full halo CMEs.
• 4.2 We have tried to improve the algorithm for
  predicting the duration intensity of Bs events
  by using the multiple regression together with
  the predicted CME speed and the new observations
  of magnetic vector field by HMI/SDO.
• 4.3 We have tried to improve the prediction of
  MCs orientation by using the local inclination
  of HCS and the N-S asymmetry of the handedness of
  helicity for CMEs originated in Bipolar closed
  regions underneath the HCS.

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4.4 We develop a way to predict the MCs
orientation using observed orientation and
handedness of EPAs for CMEs originated in
unipolar closed regions. The AIA/SDO observations
of EPAs are expected to be much better than
EIT/SOHO so that improving the prediction. 4.5
The orientation of flux ropes predicted on the
basis of the ZEC model and full halos observed by
AIA/SDO is expected to be more accurate than that
obtained from Yurchyshyn et al technique. 4.6
It is expected that the coming-up high-cadence,
high-resolution HMI/SDO and AIA/SDO observations
will make significant contribution to the space
weather research and forecasting.
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