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Title: A STEREO Survey of Magnetic Cloud Coronal Mass Ejections Observed at Earth in 2008–2012

Abstract

We identify coronal mass ejections (CMEs) associated with magnetic clouds (MCs) observed near Earth by the Wind spacecraft from 2008 to mid-2012, a time period when the two STEREO spacecraft were well positioned to study Earth-directed CMEs. We find 31 out of 48 Wind MCs during this period can be clearly connected with a CME that is trackable in STEREO imagery all the way from the Sun to near 1 au. For these events, we perform full 3D reconstructions of the CME structure and kinematics, assuming a flux rope (FR) morphology for the CME shape, considering the full complement of STEREO and SOHO imaging constraints. We find that the FR orientations and sizes inferred from imaging are not well correlated with MC orientations and sizes inferred from the Wind data. However, velocities within the MC region are reproduced reasonably well by the image-based reconstruction. Our kinematic measurements are used to provide simple prescriptions for predicting CME arrival times at Earth, provided for a range of distances from the Sun where CME velocity measurements might be made. Finally, we discuss the differences in the morphology and kinematics of CME FRs associated with different surface phenomena (flares, filament eruptions, or no surfacemore » activity).« less

Authors:
; ; ; ;  [1]; ;  [2]
  1. Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)
  2. Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
22661212
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 229; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLOUDS; ERUPTION; FILAMENTS; IMAGES; MASS; MORPHOLOGY; ORIENTATION; SOLAR CORONA; SOLAR WIND; SPACE VEHICLES; SUN; SURFACES

Citation Formats

Wood, Brian E., Wu, Chin-Chun, Howard, Russell A., Linton, Mark G., Socker, Dennis G., Lepping, Ronald P., and Nieves-Chinchilla, Teresa, E-mail: brian.wood@nrl.navy.mil. A STEREO Survey of Magnetic Cloud Coronal Mass Ejections Observed at Earth in 2008–2012. United States: N. p., 2017. Web. doi:10.3847/1538-4365/229/2/29.
Wood, Brian E., Wu, Chin-Chun, Howard, Russell A., Linton, Mark G., Socker, Dennis G., Lepping, Ronald P., & Nieves-Chinchilla, Teresa, E-mail: brian.wood@nrl.navy.mil. A STEREO Survey of Magnetic Cloud Coronal Mass Ejections Observed at Earth in 2008–2012. United States. doi:10.3847/1538-4365/229/2/29.
Wood, Brian E., Wu, Chin-Chun, Howard, Russell A., Linton, Mark G., Socker, Dennis G., Lepping, Ronald P., and Nieves-Chinchilla, Teresa, E-mail: brian.wood@nrl.navy.mil. Sat . "A STEREO Survey of Magnetic Cloud Coronal Mass Ejections Observed at Earth in 2008–2012". United States. doi:10.3847/1538-4365/229/2/29.
@article{osti_22661212,
title = {A STEREO Survey of Magnetic Cloud Coronal Mass Ejections Observed at Earth in 2008–2012},
author = {Wood, Brian E. and Wu, Chin-Chun and Howard, Russell A. and Linton, Mark G. and Socker, Dennis G. and Lepping, Ronald P. and Nieves-Chinchilla, Teresa, E-mail: brian.wood@nrl.navy.mil},
abstractNote = {We identify coronal mass ejections (CMEs) associated with magnetic clouds (MCs) observed near Earth by the Wind spacecraft from 2008 to mid-2012, a time period when the two STEREO spacecraft were well positioned to study Earth-directed CMEs. We find 31 out of 48 Wind MCs during this period can be clearly connected with a CME that is trackable in STEREO imagery all the way from the Sun to near 1 au. For these events, we perform full 3D reconstructions of the CME structure and kinematics, assuming a flux rope (FR) morphology for the CME shape, considering the full complement of STEREO and SOHO imaging constraints. We find that the FR orientations and sizes inferred from imaging are not well correlated with MC orientations and sizes inferred from the Wind data. However, velocities within the MC region are reproduced reasonably well by the image-based reconstruction. Our kinematic measurements are used to provide simple prescriptions for predicting CME arrival times at Earth, provided for a range of distances from the Sun where CME velocity measurements might be made. Finally, we discuss the differences in the morphology and kinematics of CME FRs associated with different surface phenomena (flares, filament eruptions, or no surface activity).},
doi = {10.3847/1538-4365/229/2/29},
journal = {Astrophysical Journal, Supplement Series},
number = 2,
volume = 229,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}
  • The masses of coronal mass ejections (CMEs) have traditionally been determined from white-light coronagraphs (based on Thomson scattering of electrons), as well as from extreme ultraviolet (EUV) dimming observed with one spacecraft. Here we develop an improved method of measuring CME masses based on EUV dimming observed with the dual STEREO/EUVI spacecraft in multiple temperature filters that includes three-dimensional volume and density modeling in the dimming region and background corona. As a test, we investigate eight CME events with previous mass determinations from STEREO/COR2, of which six cases are reliably detected with the Extreme Ultraviolet Imager (EUVI) using our automatedmore » multi-wavelength detection code. We find CME masses in the range of m {sub CME} = (2-7) x 10{sup 15} g. The agreement between the two EUVI/A and B spacecraft is m{sub A} /m{sub B} = 1.3 +- 0.6 and the consistency with white-light measurements by COR2 is m{sub EUVI}/m{sub COR2} = 1.1 +- 0.3. The consistency between EUVI and COR2 implies no significant mass backflows (or inflows) at r < 4 R{sub sun} and adequate temperature coverage for the bulk of the CME mass in the range of T approx 0.5-3.0 MK. The temporal evolution of the EUV dimming allows us to also model the evolution of the CME density n{sub e} (t), volume V(t), height-time h(t), and propagation speed v(t) in terms of an adiabatically expanding self-similar geometry. We determine e-folding EUV dimming times of t{sub D} = 1.3 +- 1.4 hr. We test the adiabatic expansion model in terms of the predicted detection delay (DELTAt approx 0.7 hr) between EUVI and COR2 for the fastest CME event (2008 March 25) and find good agreement with the observed delay (DELTAt approx 0.8 hr).« less
  • Predicting the arrival time and transit speed of coronal mass ejections (CMEs) near the Earth is critical to understanding the solar-terrestrial relationship. Even though STEREO observations now provide multiple views of CMEs in the heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI coronagraph data are not quite sufficient for accurate forecasting of the arrival time at Earth of a majority of CMEs. This uncertainty is due to many factors that change CME kinematics, such as the interaction of two or more CMEs or the interaction of CMEs with the pervading solar wind. In order to understand the propagationmore » of CMEs, we have used the three-dimensional triangulation method on SECCHI coronagraph (COR2) images and geometric triangulation on the J-maps constructed from Heliospheric Imagers HI1 and HI2 data for eight Earth-directed CMEs observed during 2008-2010. Based on the reconstruction, and implementing the drag-based model for the distance where the CMEs could not be tracked unambiguously in the interplanetary (IP) medium, the arrival time of these CMEs have been estimated. These arrival times have also been compared with the actual arrival times as observed by in situ instruments. The analysis reveals the importance of heliospheric imaging for improved forecasting of the arrival time and direction of propagation of CMEs in the IP medium.« less
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