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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
A05102,
doi:10.1029/2005JA011445,
2006
Coronal mass ejection geoeffectiveness depending on field orientation and interplanetary coronal mass ejection classification
Seung-Mi Kang
Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu, South Korea
Y.-J. Moon
Korea Astronomy and Space Science Institute, Daejon, South Korea
K.-S. Cho
Korea Astronomy and Space Science Institute, Daejon, South Korea
Yeon-Han Kim
Korea Astronomy and Space Science Institute, Daejon, South Korea
Y. D. Park
Korea Astronomy and Space Science Institute, Daejon, South Korea
Ji-Hye Baek
Korea Astronomy and Space Science Institute, Daejon, South Korea
Heon-Young Chang
Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu, South Korea
Abstract
In this study, we have examined the coronal mass ejection (CME) geoeffectiveness characterized by Dst ≤ −50 nT according to
the field orientation (N or S) in a CME source region and its dependence on interplanetary CME (ICME) classification (magnetic
clouds or ejecta). We first considered 133 CME-ICME pairs (1996 to 2001) whose CME source locations are identified by SOHO
Large-Angle Spectrometric Coronograph (SOHO/LASCO) and extreme ultraviolet imaging telescope (SOHO/EIT) data. Then we identified
the shapes (S or Inverse-S) of the X-ray sigmoids associated with 63 of these CMEs using Yohkoh/Soft X-Ray Telescope (SXT)
data. To determine the field orientation in the sigmoids, we applied the coronal flux rope (CFR) model and the force-free
field (FFF) model to these 63 sigmoids using SOHO/Michelson Doppler Imager (MDI) images. We present the results in contingency
tables, classified according to solar field orientation and geomagnetic storm strength/occurrence. We found that (1) the prediction
of geomagnetic storms (Dst ≤ −50 nT) based on the CFR model is much better than that on the FFF model, (2) the prediction
for magnetic clouds (MCs) is much better than that for ejecta (EJ), which implies that the field orientation of the MCs is
well conserved through the heliosphere, and (3) for about 86% of the magnetic clouds, the directions of their leading fields
are consistent with those in the CME source regions. Our results support the findings that the southward orientations of the
magnetic field in the CME source regions plays an important role in the production of geomagnetic storms.
Received 31
December
2005;
accepted 12
January
2006;
published 26
May
2006.
Keywords: geoeffective CME;
Sun-Earth connection.
Index Terms: 7513 Solar Physics, Astrophysics, and Astronomy: Coronal mass ejections (2101); 7524 Solar Physics, Astrophysics, and Astronomy: Magnetic fields; 7924 Space Weather: Forecasting (2722); 7974 Space Weather: Solar effects.
Read Full Article (file size: 540669 bytes) Cited by
Citation: Kang, S.-M., Y.-J. Moon, K.-S. Cho, Y.-H. Kim, Y. D. Park, J.-H. Baek, and H.-Y. Chang
(2006),
Coronal mass ejection geoeffectiveness depending on field orientation and interplanetary coronal mass ejection classification,
J. Geophys. Res.,
111,
A05102,
doi:10.1029/2005JA011445.
Copyright 2006 by the American Geophysical Union.
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