SUN-TO-EARTH CHARACTERISTICS OF TWO CORONAL MASS EJECTIONS INTERACTING NEAR 1 AU: FORMATION OF A COMPLEX EJECTA AND GENERATION OF A TWO-STEP GEOMAGNETIC STORM
Name
Liu-2014-SUN-TO-EARTH CHARACT.pdf
Size
1.39 MB
Format
Adobe PDF
Checksum (MD5)
8bc0bb38bf0db26d38f1a782ede22753
Author(s)
Liu, Ying D.
Yang, Zhongwei
Wang, Rui
Luhmann, Janet G.
Richardson, John D.
Lugaz, Noé
Date Issued
September 2014
Journal
Astrophysical Journal
Publisher
Institute of Physics/American Astronomical Society
Citation
Liu, Ying D., Zhongwei Yang, Rui Wang, Janet G. Luhmann, John D. Richardson, and Noé Lugaz. “SUN-TO-EARTH CHARACTERISTICS OF TWO CORONAL MASS EJECTIONS INTERACTING NEAR 1 AU: FORMATION OF A COMPLEX EJECTA AND GENERATION OF A TWO-STEP GEOMAGNETIC STORM.” The Astrophysical Journal 793, no. 2 (September 19, 2014): L41. © American Astronomical Society.
Version
Final published version
Abstract
On 2012 September 30-October 1 the Earth underwent a two-step geomagnetic storm. We examine the Sun-to-Earth characteristics of the coronal mass ejections (CMEs) responsible for the geomagnetic storm with combined heliospheric imaging and in situ observations. The first CME, which occurred on 2012 September 25, is a slow event and shows an acceleration followed by a nearly invariant speed in the whole Sun-Earth space. The second event, launched from the Sun on 2012 September 27, exhibits a quick acceleration, then a rapid deceleration, and finally a nearly constant speed, a typical Sun-to-Earth propagation profile for fast CMEs. These two CMEs interacted near 1 AU as predicted by the heliospheric imaging observations and formed a complex ejecta observed at Wind, with a shock inside that enhanced the pre-existing southward magnetic field. Reconstruction of the complex ejecta with the in situ data indicates an overall left-handed flux-rope-like configuration with an embedded concave-outward shock front, a maximum magnetic field strength deviating from the flux rope axis, and convex-outward field lines ahead of the shock. While the reconstruction results are consistent with the picture of CME-CME interactions, a magnetic cloud-like structure without clear signs of CME interactions is anticipated when the merging process is finished.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/2041-8205/793/2/l41
